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Background: Smooth muscle tumors are the second most common malignancy encountered in children with acquired immunodeficiency syndrome (AIDS). This study reviewed the incidence and endoscopic appearance of smooth muscle tumors in the gastrointestinal tract of children with AIDS undergoing endoscopy., Methods: Retrospective review of all endoscopic records (n = 70) of children with AIDS from August 1988 to December 1997 at a tertiary care inner city hospital., Results: Three children with advanced AIDS (4%) were found to have smooth muscle tumors, all of which had the typical appearance of submucosal nodules with central ulceration. Some were hemorrhagic. They measured less than 1 to 4 cm in diameter. Two children had multiple tumors. All lesions except for one were located in the colon. Colonic biopsies revealed a leiomyoma in one patient and a smooth muscle tumor of uncertain malignant potential in another. The forceps biopsy of the single gastric mass was not deep enough to make the diagnosis of a smooth muscle tumor. A nonmalignant smooth muscle tumor grew from less than 5 mm to more than 4 cm in 1 year and was removed surgically. All three children are alive without any evidence of local spread or distant metastases despite no specific therapy for the smooth muscle tumor., Conclusions: Smooth muscle tumors in the GI tract of children with AIDS are relatively common. Further study of the long-term outcome for children infected with the human immunodeficiency virus who have these lesions are needed to establish prognosis and management guidelines.

Apoplectic leiomyoma is a distinctive smooth muscle tumour usually occurring in women either taking oral contraceptives or who are pregnant or recently postpartum. Most of these tumours show 0-2 mitoses per 10 high power fields, but a mitotic index of up to 8 per 10 high power fields is allowed in such tumours. We describe an apoplectic leiomyoma with a number of atypical features including a high mitotic index (up to 20 per 10 high power fields) in a 47-year-old woman. Follow-up clinically and by computerised tomography (CT) for 3 years demonstrates no recurrence.

Gastrointestinal stromal tumor or smooth muscle tumor (GIST) is the designation for a major subset of gastrointestinal mesenchymal tumors that histologically, immunohistochemically, and genetically differ from typical leiomyomas, leiomyosarcomas, and schwannomas. Because GISTs, like the interstitial cells of Cajal, the gastrointestinal pacemaker cells, express CD117 (c-kit protein), the origin of GISTs from the interstitial cells of Cajal has been recently proposed. Comparison of GISTs primary in the omentum and mesentery to GISTs primary in the tubular gastrointestinal tract is of particular diagnostic and histogenetic interest in view of the possible similarity of these tumors with the GIST group. In this study, we analyzed 14 omental and 12 mesenteric primary mesenchymal tumors representing smooth muscle tumors or GISTs. These tumors were phenotypically compared with gastric and small intestinal GISTs, leiomyomas of the esophagus, and leiomyosarcomas of the retroperitoneum. Most (13 of 14) omental and mesenteric (10 of 12) tumors showed histologic features similar to GISTs with elongated spindle cells or epithelioid cells with high cellularity; most of these tumors showed low mitotic activity. Omental and mesenteric GISTs were typically positive for CD117 and less consistently for CD34. They often showed alpha-smooth muscle actin reactivity but were virtually negative for desmin and S-100 protein. One omental and two mesenteric tumors showed features of leiomyosarcoma with ovoid, less elongated nuclei, cytoplasmic eosinophilia; all these tumors had significant mitotic activity. These tumors were positive for alpha-smooth muscle actin and two of them for desmin, but all were negative for CD34 and CD117, similar to retroperitoneal leiomyosarcomas. Tumor-related mortality occurred in the group of mesenteric GISTs, but not in the group of omental GISTs. In contrast, all three patients with a true leiomyosarcoma of the omentum or mesentery had documented liver metastases or died of tumor. In summary, we show that tumors phenotypically identical with GISTs occur as primary tumors in the omentum and mesentery. The occurrence of CD117-positive tumors outside the gastrointestinal tract militates against an origin of these tumors exclusively from the interstitial cells of Cajal.

The c-kit gene encodes a transmembrane receptor kinase (KIT) which is expressed in the majority of human gastrointestinal stromal tumors (GISTs), a subtype of gastrointestinal mesenchymal neoplasms. A previous study identified mutations in the juxtamembrane (JM) domain of c-kit in five of six GISTs (Science 279: 577, 1998). To better define the frequency and spectrum of c-kit gene mutations in mesenchymal neoplasms of the GI tract that had been characterized for KIT protein expression, we examined archived tissue samples for mutations in the JM domain by PCR amplification and DNA sequencing. c-kit JM domain mutations were found in nine of 56 mesenchymal tumors (46 GISTs, eight leiomyomas, two leiomyosarcomas) and occurred exclusively in GISTs (21%). Seven of the nine mutations consisted of intragenic deletions of one to 19 codons. There was one insertion mutation that added 12 codons and one missense mutation (Val560Asp). None of the mutations disrupted the downstream reading frame of the gene. The single missense mutation (Val560Asp) is very similar to the only other missense mutation reported in GISTs (Val599Asp). Of the 46 GISTs, 43 were strongly positive for KIT protein expression and negative for diffuse expression of desmin. Neither KIT expression nor gene mutations were found in gastrointestinal leiomyomas or leiomyosarcomas. We conclude that mutation of the c-kit JM domain does not occur in gastrointestinal mesenchymal neoplasms with well developed-smooth muscle differentiation, and is restricted to GISTs. However, since these mutations are only found in a minority of GISTs, further investigation into the mechanisms of c-kit gene activation in this group of neoplasms is warranted.

Smooth-muscle tumors, benign and malignant, are increasingly recognized in children who are immunocompromised because of HIV infection and organ transplantation. We report a case of an EBV-associated smooth-muscle tumor, of unusual location arising in a seven-year-old post-transplant patient who was previously treated for a lymphoproliferative disease. Five years after liver transplantation, a mesenteric tumor was diagnosed. The tumor was composed of spindle cells with smooth-muscle features. Immunohistochemical analysis was positive for muscle-specific actin and desmin, negative for EBV latent membrane protein (LMP-1). In situ hybridization revealed nuclear EBV sequences. This case underlines the role of EBV infection in the development of unusual smooth-muscle tumors after organ transplantation. The evolution of these rare tumors is uncertain.

Although the significance of various prognostic factors, such as tumor size and mitotic index (MI), has been well established for smooth-muscle tumors of the stomach, the significance of these factors in other sites is less well defined. We studied 1004 patients with gastrointestinal smooth-muscle tumors for whom vital status could be determined. The average MI and tumor size varied significantly among the five major sites examined: esophagus (53 cases), stomach (524 cases), small bowel 252 cases), colon/rectum (108 cases), and omentum/mesentery/peritoneum (67 cases). There was a significant difference in site-specific survival (p = 0.001), with 10-year survival varying between 50% and 70%. Multivariate analysis demonstrated tumor location (p = 0.0320), size (p = 0.0003), MI (p < 0.0001), and patient age (p < 0.0001) to each carry independent prognostic value. The significance of MI was highly site dependent. Separation of survival curves for the stomach, using a threshold for analysis of either 5 or 10 mitotic figures/50 high-power fields, was very good. In contrast, small-bowel tumors showed little separation between survival curves, regardless of whether a threshold of 1, 5, or 10 mitotic figures MF/50 high-power fields was used to distinguish groups. In no site were tumor size and MI alone sufficient to provide an accurate long-term prediction of prognosis. Although tumor location, size, MI, and age have independent value in predicting the prognosis of patients with gastrointestinal smooth-muscle tumors, better methods are still required to accurately predict clinical course.

In order to elucidate the efficacy in gastric surgery, we evaluated seven resected cases of a submucosal gastric tumor in which laparoscopic techniques were used. The patients consisted of 1 man and 6 women. The tumors were located in the upper, middle, and lower third of the stomach in 4, 1, and 2 cases, respectively. Three tumors were located mainly on the anterior gastric wall, 2 were on the posterior wall, and 2 were on the lesser curvature. The resected tumor size averaged 3.2 x 2.6 cm. The tumors were classified as intraluminal type (4 cases) and the extraluminal type (3 cases) according to the classification of growth type. A histopathological examination identified 4 leiomyomas, 1 leiomyosarcoma, and 4 smooth muscle tumors of indeterminate malignant potential. After a tumor resection, no recurrence of the lesions occurred during the postoperative follow-up. An extraluminal growing tumor was easily resected by the laparoscopic method without any additional procedures, and this therefore seemed to be a good indication for the laparoscopic method. In contrast, an intraluminal tumor was found to be more difficult to resect using the laparoscopic method without a companion method, e.g., intraoperative endoscopy, because of the difficulties in the detection and resection of the tumor from the serosal side. A more efficient technique must therefore be developed for this type of tumor.

Gastrointestinal stromal/smooth muscle tumors (GISTs) are uncommon neoplasms for which current criteria for the diagnosis of malignancy (location, size, and mitotic index) do not always reliably predict patient outcome. Recently, mutation of KIT oncogene exon 11 has been observed in some of these tumors, but the relationship between mutation and clinical outcome has not yet been determined. DNA was obtained from the formalin-fixed, paraffin-embedded tissue of 35 gastric GISTs. A segment of exon 11 was amplified by PCR and sequenced on an ABI 377 sequencer. The relationship between the presence or absence of mutation, tumor size, and mitotic index was investigated using correlation analysis, and the relationship between mutation and outcome was investigated using Kaplan-Meier plots, the Cox-Mantel statistic, and the Cox regression model. Exon 11 deletion mutations were identified in 10 cases, and point mutations were identified in an additional 3 cases; 22 cases demonstrated no KIT mutations. KIT mutation was associated with decreased survival (p = 0.001), with fewer than 30% of patients surviving more than 3 years, compared with over 65% survival for patients whose tumors did not bear the mutation. KIT mutation did not correlate with either the mitotic index or the tumor size. In conclusion, KIT mutation is associated with poor prognosis in patients with gastrointestinal stromal tumors. Whether the KIT mutation will prove to be an independent prognostic factor awaits the completion of larger studies.

Tumours of uterine smooth muscle are poorly understood neoplasms in which the effects of steroid sex hormones are complex. The influence of progesterone and oestrogen on a transplantable rat uterine smooth muscle tumour line (SMT-Y) was investigated. Female F344 rats given subcutaneous transplants of tumour fragments developed tumours, 1.5-2 cm in diameter, and were then treated with progesterone (10 mg/rat) or 17 beta-oestradiol (50 mg/rat). Tumours in treated groups were compared with those in untreated controls. During a 9-week observation period after treatment, progesterone promoted tumour growth from 4 weeks, with increased numbers of proliferating cells. In contrast, oestradiol inhibited tumour growth from 6 weeks; the degraded tumours, consisting mainly of vacuolated neoplastic cells, had decreased numbers of proliferating cells and increased numbers of apoptotic cells, demonstrable by in-situ terminal deoxyribonucleotide transferase (TdT)-mediated dUTP nick labelling. Immunohistochemically, tumours in control and progesterone groups were labelled positively for alpha-smooth muscle actin (SMA) and desmin but not for vimentin, whereas the degraded tumours in the oestradiol group had reduced reactivity for SMA and desmin but an increased reactivity for vimentin. These results indicate that progesterone may act as a promoter for uterine smooth muscle tumour growth by stimulating mitotic activity, whereas oestrogen may have suppressive effects on tumour growth, accompanied by morphological changes.

We report a case of a previously undescribed benign neoplasm characterized by a poorly circumscribed proliferation of clear cells, arranged both singly and in elongated fascicles oriented in haphazard fashion within the middle and lower reticular dermis. The fascicles consisted of spindle-shaped cells that were periodic acid-Schiff positive and diastase labile. These cells were characterized by oval, hyperchromatic, cigar-shaped nuclei and clear cytoplasm. Immunohistochemically, neoplastic cells were diffusely positive for smooth muscle actin (1A4), common muscle actin (HHF-35), and vimentin. Immunoreactivity for fibronectin was also focally noted. The neoplasm, which we designated clear-cell smooth muscle tumor of the skin, should be distinguished from smooth muscle hamartoma and other smooth muscle proliferations at cutaneous level. We highlight in this case report the histopathologic differential diagnosis among other tumors with myofibroblastic, melanocytic, and neural differentiation.

Uterine tumors composed of a prominent component of smooth muscle (SM) and endometrial stroma (ES) (so-called stromomyomas) have received little attention in the literature. The features of 15 of these tumors, defined as those containing more than 30% of each component, were evaluated. Many of the tumors were referred because of problems in the differential diagnosis. Patient age ranged from 29 to 68 years (mean, 46 years). The tumors ranged from 3 to 27 cm (average 9.6 cm) in diameter, and most were grossly well circumscribed. The sectioned surfaces often had soft, tan-yellow areas admixed with firm, whorled areas. Microscopic evaluation disclosed that nine tumors were well circumscribed, and six had infiltrating tongues typical of endometrial stromal sarcoma (ESS). The endometrial stromal component, which predominated in five cases, typically was characterized by a diffuse growth of closely packed, minimally atypical small cells accompanied by numerous arterioles and was desmin-negative in all cases tested, except for rare desmin-positive cells in three tumors. Five tumors showed sex-cord-like differentiation in these areas. The smooth muscle component, which predominated in seven cases, was composed predominantly of spindle cells in disorganized short fascicles, longer fascicles, or nodules with prominent central hyalinization. This component appeared benign, except in one case with moderate cytologic atypia, focal tumor cell necrosis, and 4 mitotic figures/10 high-power fields. The smooth muscle component was strongly desmin-positive in all the tumors tested. Follow-up of more than 1 year was available for seven patients. Six patients were alive and well, but one tumor with infiltrative borders recurred at 48 months as a pure endometrial stromal sarcoma. Mixed endometrial stromal and smooth muscle tumors should be distinguished from highly cellular leiomyomas, pure endometrial stromal tumors, and "uterine tumors resembling ovarian sex cord tumors," at least until knowledge of their clinicopathologic features is more complete. For treatment purposes, these tumors should be reported as endometrial stromal nodules or as endometrial stromal sarcomas with smooth muscle differentiation and any unusual features of either component recorded in a notation.

A 40-year-old woman had multiple smooth muscle tumors in the left inguinal region, the bilateral thighs, the omentum, the peritoneum, and the right infundibulum pelvic ligament associated with uterine leiomyomas. She had a history of uterine leiomyomas, which were resected 13 years ago. Histopathologic evaluation revealed tumor masses composed of smooth muscle cells with relatively low cellularity, which were consistent with a diagnosis of leiomyoma. Tumor necrosis and nuclear atypia were absent. Mitotic figures were very scarce (less than 1 mitotic figure per 10 high-power fields). Immunohistochemical evaluation revealed a positive reaction of the tumor cells to muscle markers, estrogen receptors, and progesterone receptors. No pulmonary lesion was found. Similar instances of uterine leiomyomas with histologically benign extrauterine smooth muscle tumors have been reported. This curious condition has been referred to as "benign metastasizing leiomyoma," in which most of the reported cases involve the lungs. The distribution of extrauterine tumors in our case is very unusual and may be the first case with multiple leiomyomas in deep soft tissue of the limbs. Consideration was given to the concept that these may be of multifocal origin, rather than metastases.

Dural and skull-base mesenchymal neoplasms other than meningiomas are rare. We report four such tumors, some of which are uncommon even in nonintracranial sites, in three adults and one child. The adult tumors consisted of a synovial sarcoma of the third ventricle region in a 19-year-old woman, a leiomyoma of the suprasellar region in a 57-year-old woman, and an Epstein-Barr virus (EBV)-associated smooth muscle tumor of the cavernous sinus in a 35-year-old woman with acquired immunodeficiency syndrome (AIDS). The pediatric tumor was an EBV-associated leiomyosarcoma of the left dural transverse sinus in a 14-year-old girl with common variable immunodeficiency syndrome. All tumors were thought to be primary in their dural or skull-base locations. The two EBV-associated smooth muscle tumors in immunocompromised patients expand the locations for EBV-associated smooth muscle tumors to dural and skull-base sites, the synovial sarcoma is unique to the intracranial space, and the sellar leiomyoma represents the third reported sellar smooth muscle tumor.

Gastrointestinal stromal tumour (GIST) is the designation used here to identify the most common subset of gastrointestinal mesenchymal tumours specific to those sites. These tumours have unique histological, immunophenotypic and molecular genetic features that set them apart from typical smooth muscle tumours and schwannomas; however, by tradition, they have been classified as GI-smooth muscle tumours, or stromal tumours/smooth muscle tumours. GISTs occur predominantly in persons over 40 years of age with an equal sex incidence. Benign GISTs outnumber the malignant ones by a margin of 10:1. GISTs occur throughout the gastrointestinal tract, but are most common in the stomach (60-70%) and small intestine (30%). GISTs are rare in esophagus, colon and rectum. Histologically they may show a spindle cell or epithelioid pattern (the former largely corresponds with the designation of cellular leiomyoma and the latter with that of leiomyoblastoma). Immunohistochemically most GISTs are positive for CD34 and c-kit protein (CD117); the latter is quite specific for GISTs among mesenchymal tumours. Genetically GISTs commonly show DNA losses in the long arm of chromosome 14, and c-kit gene mutations occur at least in some cases. c-kit is also expressed in the interstitial cells of Cajal, the gastrointestinal pacemaker cells, and relationship of GISTs to these cells has been proposed recently. GISTs differ histologically, immunohistochemically and genetically from typical (esophageal) leiomyomas that are negative for c-kit and CD34 and neither show DNA-losses in 14q nor c-kit mutations. Evaluation of malignancy of GISTs is based on mitotic count, tumour size and extra-gastrointestinal spread. Tumours with mitotic counts higher than 5/10 high power fields or larger than 10 cm have a significant risk for recurrence and metastasis and are considered histologically malignant; however, some tumours with mitotic activity < 1/10HPF may metastasize indicating some uncertainty in malignant potential of GISTs, especially those larger than 5 cm.

Smooth muscle tumors of the gastrointestinal tract are difficult to evaluate and to stage. Twenty-four patients surgically treated during the last ten years have been evaluated using a TGM staging to identify the more rational criteria for the therapeutic choice. Six gastric leiomyomas, 1 ileal leiomyoma, 4 gastric leiomyosarcomas, 1 esophageal leiomyosarcoma, 4 ileal leiomyosarcomas, 2 rectal leiomyosarcomas and 6 gastric leiomyoblastomas were included. 62.5% of cases presented acute clinical features. Preoperative histological diagnosis was adequate in 29% of cases. We performed 7 excisions, 6 gastric subtotal resections, 3 total gastrectomies, 1 esophageal resection, 5 ileal resections, 2 rectal low anterior resection. Fourteen patients were staged I/II, 8 staged III and 2 staged IV. The overall median survival time was 27.5 months (56, 20 and 5 months concerning stage I/II, III and IV respectively; p < 0.01). In relation to T and G factors overall survival was statistically significant. TGM staging was highly significant to predict long-term survival. Radical surgical procedure was highly effective to guarantee long-term survival. Extended follow up is requested because recurrences after many years seem to be possible also with low histologic grade at first presentation.

Background: Incidence of smooth muscle tumors is increased in patients with human immunodeficiency virus infection and organ transplant recipients. Smooth muscle tumors in immunocompromised patients often occur in unusual locations and exhibit evidence of latent infection by clonal, presumably tumorigenic, Epstein-Barr virus (EBV)., Objective: To investigate the presence of EBV latent infection in smooth muscle tumors in patients with acquired immunodeficiency syndrome and in immunocompetent patients., Design: Twenty-two extrauterine, extraintestinal smooth muscle and myofibroblastic tumors were reviewed pathologically, and clinical charts were screened. Tumors were malignant (15 patients), benign (6 patients), and borderline (1 patient). Tissue specimens were investigated for latent EBV infection by latent membrane protein immunocytochemistry and EBV-encoded RNA in situ hybridization., Setting: University Hospital of the University of Nancy, France., Patients: Patients were 18 adults and four children. Two adults had acquired immunodeficiency syndrome. Both had low-grade leiomyosarcomas located in adrenal gland. Moreover, in patient 1, leiomyosarcoma was multifocal in pericardium and lymph node; in lymph node, muscle tumor was adjacent to nodal and skin Kaposi's lesions., Results: In both patients with acquired immunodeficiency syndrome and leiomyosarcoma, latent infection by EBV could be demonstrated in tumor cells, contrasting with absence of detectable EBV infection in adjacent non-neoplastic tissues and nearby Kaposi's lesions. Latent infection by EBV could not be demonstrated in smooth muscle and myofibroblastic tumors in immunocompetent patients., Conclusions: Latent EBV infection is associated with smooth muscle cell tumors in immunocompromised patients, but not in immunocompetent patients.

A preliminary study was undertaken to assess the feasibility and the diagnostic role of fine-needle aspiration cytology (FNAC) in the preoperative evaluation of eight uterine smooth muscle tumors manifesting as single large masses with signs of growth. Percutaneous FNAC was performed under echographic control with a 22-gauge needle and the material was stained according to conventional techniques. Histology of surgically resected specimens was available for final diagnosis and comparative analysis in all the cases, including five leiomyomas (LM), one smooth muscle tumor of uncertain malignant potential (TUMP), and two low-grade leiomyosarcomas (LMS). Cellularity, as indicated by the density (crowding) of nuclei reflecting the amount of cytoplasmic volume, and the cohesiveness of the tissue fragments in the smears appeared to be the most important diagnostic parameters in the distinction between LM and LMS. LM usually showed few scattered poorly cellular fragments of highly cohesive tapering cells without nuclear crowding and with abundant cytoplasm. LMS usually showed a large number of single cells and fragments of loosely arranged tapering cells with nuclear enlargement and crowding and ill-defined scanty cytoplasm. Borderline forms such as TUMP were hardly distinguishable from LMS and LM. FNAC appears to be a feasible preoperative procedure in uterine smooth muscle tumors and may play a diagnostic role, especially in distinguishing frankly benign from overtly malignant forms.

Epithelioid smooth-muscle tumors of the uterus are uncommon neoplasms for which prognostic factors have not been well established. A retrospective follow-up study of 18 uterine epithelioid smooth-muscle tumors was performed. Patients ranged in age from 27 to 83 years (mean, 45 years) and were separated into three groups based on the nuclear grade of the epithelioid tumor cells. Two tumors had grade 1 nuclei; both were examples of intravenous leiomyomatosis. They had highest mitosis counts of 1 and 3 mitotic figures (MF)/10 high-power fields (HPF), no tumor cell necrosis was found, and both patients were alive with no evidence of disease at 64 and 5 months' follow-up. Ten tumors had grade 2 nuclei. All had highest mitosis counts of 0 to 3 MF/10 HPF, except one (5 MF/10 HPF). Tumor cell necrosis was absent in nine and only one had an infiltrative border. Tumor size ranged from 1.5 to 14 cm. Two tumors contained pleomorphic ("symplastic") multinucleated giant cells similar to those seen in bizarre leiomyomas. All nine patients with follow-up were alive with no evidence of disease 5 to 203 months postoperatively (median, 74 months). One patient had also received adjuvant radiation therapy. Six tumors had grade 3 nuclei. Highest mitosis counts of 4 to 9 MF/10 HPF were found in five; one had 1 MF/10 HPF. Maximum tumor size ranged from 4.5 to 13 cm. Two had tumor cell necrosis, and two had an infiltrative border. Two of these patients died of tumor 11 and 132 months postoperatively. The former had widespread metastases at initial surgery (stage IVb); the latter patient (stage I) developed the first of seven tumor recurrences 3 years postoperatively. Both patients had also received adjuvant chemotherapy. Of the remaining four patients, two were alive with no evidence of disease at 48 and 83 months, one was alive (tumor status unknown) at 28 months, and one was lost to follow-up. Based on our findings and those in the literature, we conclude that uterine smooth-muscle tumors with a predominance of epithelioid cells are extremely uncommon and metastasize infrequently. No single histologic feature is predictive of metastatic potential. Clinically malignant tumors (i.e., epithelioid leiomyosarcomas) typically have the combination of significant nuclear atypia (either grade 2 or grade 3 nuclei) and some mitotic activity (usually at least 3 to 4 MF/10 HPF); most also have tumor cell necrosis.

Objective: To assess the utility of fine needle aspiration biopsy (FNAB) in retroperitoneal spindle cell tumors with difficult tumor typing., Study Design: Thirty-six cases of spindle cell tumors of the retroperitoneum were studied. Cytological diagnoses were set progressively: first exclusively by morphologic criteria on routinely stained slides, and then with the aid of immunocytochemistry (ICC), electron microscopy (EM) and clinical data., Results: The morphologic diagnosis of benignity or malignancy was first made in double blind fashion by two researchers; it permitted an exact diagnosis in 31 cases (86%) by one examiner and 27 cases (75%) by the second. Using a progressive approach, benignity or malignancy was definitively determined in 35 cases (97%). As far as cytologic tumor typing is concerned, first it proved to be possible in 27 cases (75%) and then in 30 cases (83%) with the progressive approach., Conclusion: FNAB proved to be a useful tool in the diagnosis of retroperitoneal spindle cell tumors. A progressive approach to cytopathologic diagnosis, correlating morphology with ICC and EM results and matching them with clinical data, permitted a better differential diagnosis between benign and malignant spindle cell tumors and increased the possibility of correct tumor typing.

Background: Primary smooth muscle tumors of the thyroid gland are rare. To date, there are few cases reported of primary thyroid leiomyomas and leiomyosarcomas., Methods: One leiomyoma and four leiomyosarcomas arising within the thyroid gland were identified in the files of the Endocrine Tumor Registry of the Armed Forces Institute of Pathology. Histologic and immunohistochemical features were reviewed and follow-up obtained., Results: The patients included 2 females, ages 56 and 64 years, and 3 males, ages 45, 68, and 83 years. The patients presented with a mass in the thyroid gland that had increased in size over a number of months. All the tumors originated within a single lobe of the thyroid gland and measured from 1.1 to 9 cm in greatest dimension. Histologically, there was a fascicular pattern of growth comprised of spindle-shaped cells with blunt-ended nuclei. The leiomyoma was encapsulated, cytologically bland, and amitotic; the leiomyosarcomas were invasive with increased cellularity, pleomorphism, a high mitotic rate, necrosis, and hemorrhage. Immunohistochemical staining showed reactivity with vimentin, smooth muscle actin, muscle specific actin, and desmin. The patient with the leiomyoma was alive without evidence of disease 11 years after the initial presentation, with surgical resection as the only treatment. Three of the patients with leiomyosarcomas were dead within 2 years of diagnosis, in spite of aggressive therapeutic intervention. The remaining patient was still alive 10 months after initial presentation with multiple lung metastases., Conclusions: Smooth muscle tumors of the thyroid gland are distinctive tumors. Leiomyosarcomas can be distinguished from anaplastic carcinoma, although patient outcome is uniformly unfavorable.

To discuss the diagnosis of uterine leiomyosarcoma and leiomyoma of cellular and bizarre type, we reviewed 51 cases and carried out P53 and desmin immunohistochemical staining on 43 cases. We found that in most cases leiomyosarcoma is accompanied by nuclear mitosis, cell atypia and margin infiltration. In a small number of cases, though mitotic figures are scarce, high cell atypia and marked margin infiltration were present. Leiomyoma variants may have high cellular density and bizarre nuclears but have no margin infiltration. Leiomyosarcoma has a high incidence of P53 expression, while no P53 expression was detected in leiomyoma variants. Desmin expression is closely correlated with the differentiation of smooth muscle neoplasms of the uterus. We conclude that nuclear mitotic activity is an important but not independent criteria in the diagnosis of uterine leiomyosarcoma. Cellular atypia and margin infiltration should be considered. P53 and desmin expression can be applied as accessary criteria.

Epstein-Barr (EB) virus-associated primary smooth muscle tumors have been reported in immunosuppressed young patients with acquired immunodeficiency syndrome (AIDS) and young people who have undergone liver transplantation. An autopsy case of EB virus-associated smooth muscle cell tumor in a 21 year old female who received immunosuppressive therapy following renal transplantation is reported. Multiple tumor nodules were present in the liver, but no primary lesion was found in any other organ. Histologically, the nodules were composed of spindle cells, positive for alpha-smooth muscle actin, which were arranged in fascicles and closely associated with vascular channels, thereby suggesting a vascular smooth muscle cell origin. EB virus infection of the tumor cells was clearly demonstrated by in situ hybridization with an EB virus-encoded RNA 1 (EBER-1) probe. The present case illustrates that EB virus infection may play some role in the development of smooth muscle tumors not only in immunocompromised young patients with liver allografts, but also in those with renal allografts.

The clinical and pathological features of 25 smooth-muscle tumors of the vulva were analyzed. The patients ranged in age from 17 to 67 (mean, 37.6) years; two were pregnant. Twenty-three tumors were 1.5 to 16 (mean, 5.2) cm in greatest dimension; the size of two tumors was unknown. Microscopic examination showed that 16 tumors were circumscribed, six had focally infiltrative margins, and the margins could not be evaluated in three tumors. Fourteen tumors were composed mainly of spindle cells; two of these tumors had prominent myxoid stroma. Seven tumors were predominantly epithelioid and had a prominent hyalinized or myxoid stroma; often the cells had a plexiform pattern. Four tumors contained an approximately equal number of epithelioid and spindle cells. Ten tumors had mild, nine moderate, and six severe cytologic atypia. Mitotic figures ranged from 0 to 10 (average, 1.8) per 10 high-power fields (hpf). Immunohistochemically, all the tumors stained for one or more muscle markers. Thirteen of 17 tumors were positive for estrogen receptors, and 16 of 18 were positive for progesterone receptors. Follow-up information ranging from 1 month to 19 years (average, 5 years) was available in 19 cases. Four tumors recurred locally, and one patient with recurrent tumor died of metastases 7 months after the initial operation. We propose an expanded criteria to distinguish between leiomyomas and leiomyosarcomas of the vulva. Tumors that manifest three or all of the four following features should be considered sarcomas: > or = 5 cm in greatest dimension, infiltrative margins, > or = 5 mitotic figures per 10 hpf, and moderate to severe cytologic atypia. Those that have only one of these characteristics should be diagnosed as leiomyoma, and those that exhibit only two of these features should be considered benign but atypical leiomyomas. The sarcomas should be excised with widely negative margins; the leiomyomas and the atypical leiomyomas should be excised conservatively, with long-term, careful follow-up.

Fifty-six gastrointestinal stromal tumors (GIST) were subclassified by ultrastructural examination and by immunophenotypic analysis using a panel of 13 antibodies. Eighty percent of the tumors originated in the stomach and small intestines. The neoplasms were classified as follows: 42.9% smooth muscle tumors (4 leiomyomas, 9 spindle cell and 8 epithelioid leiomyosarcomas, and 3 mixed spindle cell and epithelioid leiomyosarcomas); 37.5% gastrointestinal autonomic nerve tumors (GANT), 47.6% of which arose in the small intestines; 8.9% mixed leiomyosarcoma/neurogenic tumors; and 10.7% undifferentiated GIST, not otherwise specified. The muscle common actin antibody HHF-35, variably reactive with tumor cells composing 23 of 24 smooth muscle tumors, was found to be the most sensitive marker of leiomyocyte differentiation. One immunophenotypically questionable spindle cell leiomyosarcoma was diagnosed by electron microscopy. Since neuron specific enolase positive cells were found in 1/3 of the leiomyosarcoma cases, the ultrastructural demonstration of synapse-like structures and neurosecretory granules was required for diagnosing GANTs. The immunophenotype of the ultrastructurally undifferentiated GIST was vimentin and CD34+. Variable numbers of ultrastructurally undifferentiated cells also we found in all of the tumors except 2 leiomyomas. CD34 was also expressed in smooth muscle (54%) and GAN (62%) tumors. Despite their similar light microscopic appearance, GIST are phenotypically heterogeneous, requiring both ultrastructural and immunohistochemical studies for accurate characterization.

bcl-2 is a proto-oncogene which inhibits apoptosis. In contrast, p53 tumour suppressor gene is known to induce apoptosis. In this study we analysed immunohistochemically 63 mesenchymal tumours for the expression of bcl-2 and p53 proteins with a special emphasis on muscle-derived tumours. bcl-2 was expressed in all seven rhabdomyosarcomas and in five out of seven leiomyosarcomas. In benign muscle tumours, bcl-2 expression was found in all four epithelioid leiomyomas and in six out of 14 leiomyomas. In non-neoplastic muscle cells, occasional weak bcl-2 positivity was found in muscle cells of vascular walls and myometrium. In mesenchymal tumours of other lineages, bcl-2 positivity was only found in four out of 12 malignant fibrous histiocytomas and in one out of three liposarcomas. p53 positivity was found in 14 tumours, 13 of which were sarcomas. No association was found between p53 and bcl-2 positivity. Our results suggest that bcl-2 expression is activated significantly more often in muscle derived tumours than in mesenchymal tumours of other lineages. Our results also suggest that p53 status does not directly affect the expression of bcl-2 in sarcomas.

Smooth muscle tumors are the most common type of uterine neoplasm. The vast majority of such tumors are benign leiomyomas. Leiomyosarcomas fortunately are relatively infrequent. A variety of gross and microscopic features may be found in both benign and malignant tumors and great care must be taken not to mistake leiomyomas with atypical or unusual features of leiomyosarcomas. Individual features, such as hypercellularity, necrosis, nuclear atypia, mitotic figures, and intravascular growth, are ominous but must be interpreted with caution because variants of benign leiomyoma may contain such changes.

Tumor-associated hypoglycemia has been reported in dogs with pancreatic beta-cell tumors, hepatic tumors, and, rarely, with other neoplasms. This article describes 4 dogs with marked hypoglycemia associated with smooth muscle tumors (jejunal leiomyoma, gastric leiomyoma and leiomyosarcoma, and splenic leiomyosarcoma). Presenting clinical signs included grand mal seizures, lethargy, weakness, ataxia, and, in 1 dog, polyuria/polydipsia. The serum insulin concentration was low in 1 dog and normal in the other dog evaluated. Immunohistochemical staining for insulin was negative in the 4 tumors; the 3 tumors arising from the stomach and jejunum stained diffusely positive for glucagon. Blood glucose concentrations rapidly returned to normal after complete surgical resection of the tumors, and clinical signs associated with hypoglycemia resolved. Long-term follow-up available in 3 of the 4 dogs found no recurrence of clinical signs related to hypoglycemia at 15, 31, and 38 months after surgery, respectively.

Uterine smooth muscle tumors are common and pose a significant public health problem for women of reproductive age. Although most uterine smooth muscle tumors are benign, pathologic diagnosis of the infrequent malignant leiomyosarcoma is important for clinical management and prediction of clinical outcome. Pathologic criteria for diagnosing malignancy in uterine smooth muscle tumors and studies of their validity are reviewed. Advances in the cytogenetic and molecular biologic study of uterine leiomyomas and their variants are being made which may ultimately change our understanding of their pathobiology, diagnosis, and potentially, their treatment.

Background: Smooth muscle tumors presenting as mediastinal soft tissue masses are extremely rare and often are mistaken for other neoplastic conditions., Methods: Ten cases of patients with malignant smooth muscle tumors presenting as mediastinal soft tissue masses were studied and correlated with their clinical behavior. Tissues were examined histologically and with immunohistochemical stains in all cases, and by electron microscopy in two cases., Results: The patients' ages ranged from 26 to 71 years (mean, 56 years); three were women, and seven were men. Three cases were located in the anterior mediastinum and seven in the posterior mediastinum. The patients with anterosuperior mediastinal tumors all presented with signs and symptoms referable to their lesions; the patients with posterior mediastinal masses (with the exception of one) were all asymptomatic. Grossly, the lesions were well circumscribed and unencapsulated, ranging from 6 to 18 cm in greatest dimension and showed a homogeneous, rubbery cut surface with prominent cystic and myxoid areas. The tumors in all patients appeared to arise from the soft tissues within the mediastinum and were unrelated to adjacent structures. In three patients, the tumors compressed and displaced the esophagus without infiltrating its wall, and in one patient, the tumor was found in close proximity, although unattached, to a large vessel. Histologically, the lesions exhibited a spectrum of morphologic appearances that ranged from low grade leiomyosarcoma with mild-to-moderate nuclear atypia and low mitotic activity (< 3/10 high power fields [HPFs]), to high grade tumors with marked nuclear pleomorphism, extensive areas of necrosis, and high mitotic activity (> 10 mitoses/10 HPFs). One case was characterized by a striking epithelioid morphology with large, round cells arranged in small clusters; another was associated with an incidental microscopic focus of thymic seminoma in the adjacent thymus. Immunohistochemical stains in all cases showed positive labeling of the tumor cells with smooth muscle actin, desmin, and vimentin antibodies. Electron microscopy in two cases showed features of smooth muscle differentiation, i.e., spindle cells surrounded by basal lamina material, immature cell junctions, and abundant intracytoplasmic filaments with focal condensations. All patients were treated with surgical excision. On follow-up, three patients with Stage IIIb and IVa tumors died 2-7 years after surgery, and two patients with Stage Ib and IIb were alive and well 4 and 6 years after surgery, respectively., Conclusion: Leiomyosarcomas may arise as primary tumors originating from mediastinal soft tissues in both anterior and posterior compartments. Because of their large size and frequent areas of cystic and myxoid degeneration, they may be confused histologically with neural or other neoplasms. As with their counterparts in other soft tissue locations, histologic grade and clinical stage are the most useful parameters for assessing prognosis.

Atypical myxoid smooth muscle tumor (AMSMT) of the prostate is a rare neoplasm not previously described in the radiographic literature. This report describes the unusual appearance of this tumor during endorectal ultrasound (ERUS), color Doppler imaging (CDI), and magnetic resonance imaging (MRI) in a 26-year-old man.

We evaluated the immunophenotypes of 22 spindled and 36 epithelioid uterine smooth muscle neoplasms (SMNs) and 16 extrauterine nongastrointestinal spindled smooth-muscle neoplasms for various markers. The epithelioid neoplasms were subdivided into two histological groups designated true and intermediate, the former showing typical epithelioid features and the latter showing epithelioid features that could be explained by cross-sectioning of blunt spindled cells. Desmin, muscle-specific actin, and smooth muscle actin were equally sensitive in detecting muscle differentiation in all these neoplasms. The true epithelioid variants were more frequently keratin positive but less frequently positive for vimentin, CD34 or the muscle markers, compared with their spindled counterparts. The intermediate epithelioid variants more closely resembled the spindled neoplasms in their immunostaining for muscle markers, vimentin, and CD34 but like the true epithelioid variants were relatively frequently positive for keratin. CD34 was positive in 36% of the spindled and 6% of the true epithelioid uterine SMNs, in most cases faintly. Antikeratin AE1 was positive more frequently than CAM5.2, with 18% of the spindled and 35% of the true epithelioid neoplasms being AE1 positive. The immunophenotype of uterine SMNs, including the epithelioid variant, permits their distinction from carcinomas based on their frequent reactivity for muscle markers in spite of their high rate of keratin positivity. They show sufficient overlap in immunoreactivity with endometrial stromal sarcomas to preclude definitive differentiation from them on immunohistochemical features alone.

Objective: To determine whether tumors meeting the criteria of Hendrickson and Kempson for uterine smooth-muscle tumors of uncertain malignant potential have a natural history different from those of leiomyomas and leiomyosarcomas., Methods: Tumors with five to ten mitoses per ten high-power fields and with mild or moderate cellular atypia were classified as tumors of uncertain malignant potential. Tumors with two to four mitoses per ten high-power fields and severe cellular atypia would also be classified as tumors of uncertain malignant potential, but we had no tumors that fell into this latter group. Forty-seven women with leiomyosarcoma or smooth-muscle tumors of uncertain malignant potential were identified. Paraffin-embedded blocks were recut, and hematoxylin and eosin-stained sections were studied for mitotic counts and cellular atypia. Statistical analysis used chi 2, Fisher exact test, Student t test, and Kaplan-Meier life table analysis., Results: Fifteen tumors were classified as uncertain malignant potential and 32 as leiomyosarcomas. The patients with leiomyosarcoma were significantly older and more likely to present with extrauterine disease. Those with tumors of uncertain malignant potential had a 5-year disease-free survival of 66% and overall survival of 92%, compared to 28 and 40%, respectively, for leiomyosarcomas; these differences were statistically significant. Patients with tumors of uncertain malignant potential tended to have a protracted clinical course after development of recurrence, and several survived longer than 5 years with metastatic disease., Conclusions: Patients with five to ten mitoses per ten high-power fields and mild to moderate cellular atypia had a prognosis significantly better than that of patients with leiomyosarcomas. In this group, only 27% developed a recurrence, and after recurrence they tended to have a protracted course. Some of these tumors do have a very aggressive course, and the term "uncertain malignant potential" is appropriate.

Smooth muscle tumors of the esophagus (n = 29), stomach (n = 30), small intestine (n = 31) and large intestine (n = 12) were examined histologically and immunohistochemically for vimentin (Vim), desmin (Des), S100, fibronectin (FN) and cytokeratin (Cyt) and for nucleolar organizer regions (AgNOR). There were 49 cases of leiomyoma (LM), 51 cases of leiomyosarcoma (LS) and 2 cases of leiomyoblastoma(LB). Histologically, LS was characterized by cellular atypia, more cells in mitosis and invasion to adjacent normal tissue. No mitotic figure was observed in LM. AgNOR was more abundant in number in LS than LM (P < 0.001), but it had no direct relation to tumor size, number of cells in mitosis and patients' survival period. Immunohistochemical studies of Vim, Des, S100, FN and Cyt revealed that none of them was very helpful in the differential diagnosis of LM from LS.

Two cases of myxoid smooth muscle tumours of the uterus have been reported. Clinical and morphological characteristics are briefly described. Inspite of the lack of cellular and nuclear atypia and mitotic figures below 2 in 10 high power fields, the clinical course was very malignant. A review of the literature on this new entity from the last 10-12 years has been made.

Plexiform tumorlet is a rare lesion usually found in the myometrium and is believed to be a variant of epithelioid leiomyoma. Multiple plexiform tumorlets may have an infiltrative pattern and mimic endometrial stromal sarcoma. Only five cases of multiple plexiform tumorlets of the uterus have been reported, to the best of our knowledge. We now present the sixth case.

A subcutaneously transplantable tumour (SMT-Y) was established from a smooth muscle tumour arising from the uterus of a female F344 rat. SMT-Y was serially passaged by subcutaneous implantation into syngeneic female rats up to the 15th generation, but transplantation failed in males. The rat with the primary uterine tumour also had mononuclear cell leukaemia (MCL), and MCL cells grew concurrently in implanted rats. At passage five, MCL cells were eliminated from transplants by implanting the central part of an SMT-Y nodule, consisting only of neoplastic smooth muscle cells. SMT-Y at passages six to 15 was examined biologically and morphologically. The primary tumour and SMT-Y tumours consisted mainly of interlacing fascicles of elongated and fusiform neoplastic smooth muscle cells with abundant cytoplasm. Occasional cells showed nuclear atypia. Mitosis counts per 10 high-power microscopic fields in the primary tumour and SMT-Y ranged from 11 to 36. Neoplastic cells reacted positively for desmin, muscle actin and myosin, but not for myoglobin. Electron microscopy revealed cytoplasmic myofilaments with oval dense bodies. These findings suggested a smooth muscle origin of SMT-Y and it was regarded as a leiomyosarcoma by the criteria for human uterine smooth muscle tumours. Despite the malignant histological features, SMT-Y grew slowly into a large nodule, with an average diameter of 5 cm and average weight of 81 g, 24 weeks after transplantation. Neither invasive tumour growth nor metastases were observed in SMT-Y-bearing rats.

We report a primary smooth-muscle tumor of undetermined malignant potential of the liver in a child with acquired immune deficiency syndrome (AIDS). This patient represents the eighth child infected with the human immunodeficiency virus who developed a mesenchymal tumor other than Kaposi's sarcoma. All these children were younger than 10 years of age. These tumors often were histologically or clinically malignant and all but one were smooth-muscle tumors. These tumors arose exclusively in visceral organs, and the hepatobiliary, gastrointestinal, and tracheopulmonary systems were involved. Transmission of the virus occurred both vertically (in six children) and via blood transfusion (in two). Given the rarity of smooth-muscle tumors in uninfected children, the unusual frequency of these tumors suggests that immunosuppression induced by the virus permits the unregulated proliferation of a primitive mesenchymal cell disposed to myogenous differentiation, a situation not unlike that observed in the development of AIDS-related Kaposi's sarcoma in adults.