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Abstract: To investigate the clinical and pathological characteristics in patients with pulmonary inflammatory pseudotumors (PIP).This retrospective study included 31 patients with PIP from 2001 to 2019. Preoperative computed tomography scan was performed in all patients. Clinical and pathological characteristics were collected and analyzed.Thirty-one patients (16 female and 15 male) were recruited, with a median age of 57 years (range, 11-72 years). Eight (25.8%) patients were asymptomatic, and the others had symptoms characterized by cough with sputum, chest and back pain, dry cough, fever and blood in sputum, or hemoptysis. All cases were single lesions, including 23 cases in the right lung, and 8 cases in the left lung. Computed tomography scan demonstrated irregular lobulated nodules or masses in 14 patients, and regular round or oval nodules or masses in 11 cases. The blurred edge of tumors and spiculation was found in 12 cases. Microscopic results were characterized by the collection of inflammatory mesenchymal cells. Immunohistochemical examination showed vimentin, smooth muscle actin, and anaplastic lymphoma kinase positive. Complete tumor resection was obtained in all cases. No recurrence or metastasis was observed during the follow-up period.PIP has a variety of manifestations. Preoperative diagnosis is difficult to reach. The final diagnosis still depends on the pathological and immunohistochemical examination. Complete surgical resection is the main treatment at present, and the overall prognosis is good., Competing Interests: The authors have no funding and conflicts of interest to disclose., (Copyright © 2021 the Author(s). Published by Wolters Kluwer Health, Inc.)

A 69-year-old man was diagnosed with a liver abscess and received antibiotics at a local hospital. He was referred to our hospital due to a persistent fever. He had hepatic masses protruding from the liver surface toward the transverse colon. We reached a diagnosis of inflammatory pseudotumor (IPT) by a percutaneous liver biopsy. Colonoscopy showed direct invasion of IPT to the colon. His condition improved by the intravenous administration of antibiotics. Hepatic IPT is often misdiagnosed as a malignant tumor. We should consider IPT when we encounter hepatic tumors, and a percutaneous liver biopsy is useful for avoiding unnecessary excessive treatments.

A 55-year-old man with a history of haemophilia A and bilateral haemophilic arthropathy of the elbows presented with an enlarging left elbow mass and worsening paresthesias in the ulnar distribution of the left hand. The mass, originally thought to be olecranon bursitis and treated as such, was found to be due to a haemophilic pseudotumour. The patient underwent successful excision of the haemophilic pseudotumour with concomitant ulnar nerve decompression and had sustained resolution of the pseudotumour and symptoms at 10 years of follow-up. This case demonstrates the need for consideration of haemophilic pseudotumour in the differential diagnosis for olecranon masses and cubital tunnel compressive neuropathy in patients with haemophilia, and highlights the viability of surgical excision as a therapeutic option for the treatment of haemophilic pseudotumours in the elbow., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2019. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Inflammatory pseudotumor is a histologically proven benign tumor-like lesion of unknown etiopathogenesis. It is less commonly found in central nervous system, and least commonly in the spinal canal. Spinal epidural inflammatory pseudotumor is a rarely reported entity., Case Description: We report a patient who presented with paraplegia, in whom a spinal epidural mass was diagnosed as an inflammatory pseudotumor after surgical excision followed by histopathology., Conclusions: It was a radiologic dilemma; thus, complete excision was required for diagnosis and a better outcome., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Inflammatory myofibroblastic tumor (IMT) is a benign neoplasm of intermediate biologic potential. It rarely occurs in the larynx, and it has not been previously reported in the epiglottis. We treated a 66-year-old woman who presented with progressive dysphonia and a mass on her suprahyoid epiglottis. The tumor was completely excised with a CO 2 laser; no adjuvant therapy was administered. Histopathology revealed that the mass was an IMT. No evidence of recurrence was noted after 6 months of follow-up. We present what we believe is the first case of an epiglottic IMT to be reported in the literature, and we propose CO 2 laser excision without adjuvant therapy as an acceptable treatment.

IgG4-related disease (IgG4-RD) is a multi-system fibro-inflammatory disorder with classical histopathological findings, often in the context of elevated serum IgG4 levels. The thoracic manifestations of IgG4-RD are numerous and can mimic several common and better known conditions. The objective of this study was to outline the frequency and nature of thoracic involvement in a prospective cohort of IgG4-RD patients who met defined diagnostic criteria. Over 40% of IgG4-RD patients had clinicoradiological and/or histological evidence of thoracic involvement, predominantly mediastinal lymphadenopathy, the majority associated with multi-system disease outside the chest. Thoracic involvement was associated with a higher serum IgG4 level, potentially representing greater disease activity or spread. Our data highlight the diverse nature of thoracic IgG4-RD, and the importance of knowledge and recognition of the condition among respiratory physicians who are likely to encounter this disease entity on an increasing basis., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Background: Inflammatory pseudotumor is a rare clinical condition that can be related to immunoglobulin G4 disease. Only a few cases of spinal inflammatory pseudotumors have been reported in the literature and an association with immunoglobulin G4 disease was not conclusive in any of them. We describe what we believe to be the first biopsy-proven case of an epidural inflammatory pseudotumor related to immunoglobulin G4 disease., Case Presentation: A 57-year-old Caucasian woman presented to our hospital with severe paraparesis, gait disturbance, and sensory loss secondary to a relapsing epidural mass. Examination of a biopsy specimen revealed a lymphoplasmacytic infiltration with fibrosis and an immunoglobulin G4-positive plasma cell ratio of over 50 %, which are compatible with a diagnosis of immunoglobulin G4-related inflammatory pseudotumor. Our patient was successfully treated with systemic and epidural administration of glucocorticoids., Conclusion: Immunoglobulin G4-related disease is an emerging clinical condition in which central nervous system involvement is still uncommon. We describe the case of a patient with an epidural mass with medullar compression, which was proved to be an immunoglobulin G4-related epidural inflammatory pseudotumor. Our findings suggest a new manifestation of immunoglobulin G4-related disease. This disorder should be considered in the differential diagnosis of spinal tumors as a potentially treatable condition with glucocorticoids.

We report a case of a patient presenting with abdominal pain, weight loss and CT imaging showing mass lesions in the chest and abdomen associated with lymphadenopathy. He was diagnosed as having IgG4-related disease and responded well to steroid treatment.

Objectives: Inflammatory myofibroblastic tumor (IMT) is a borderline neoplasm with uncertain malignant potential. It is a rare disease also referred to as an inflammatory pseudotumor, a plasma cell granuloma, and an inflammatory fibrosarcoma. IMT rarely also involves the head and neck region with only 50 cases of laryngeal IMT reported in the literature, and this is the first case with reported magnetic resonance imaging (MRI) findings., Methods: A 37-year-old man with a 1-year history of hoarseness, dysphagia, and fatigue presented with a right vocal fold submucosal mass and was treated conservatively., Results: The MRI of the neck revealed a mildly spontaneously hyperintense right true vocal fold on GRE images and relative hyperintensity on fat-saturation T2-weighted images. A biopsy of the right-sided submucosal laryngeal mass was performed and the pathologic examination revealed a lesion consistent with an IMT., Conclusion: IMT is a borderline neoplasm with uncertain malignant potential. There are many variants of IMT and its etiology is not truly understood. In general, IMT of the larynx has a benign clinical course with low rates of recurrence., (Copyright © 2014 The Voice Foundation. Published by Mosby, Inc. All rights reserved.)

Inflammatory myofibroblastic tumor is a neoplasm of intermediate biological potential, a marked inflammatory component, and characteristic genetic changes. Once it was identified as an independent nosological entity from a rather heterogeneous group of inflammatory pseudotumors. This paper describes a case of inflammatory myofibroblastic tumor of the chest in a child, by discussing the criteria for differential diagnosis in the use of up-to-date radiology techniques. When thoracic neoplasms are detected, it is necessary to determine their site and the most likely origin organ as exactly as possible and to assess the X-ray pattern of the pathological process. By applying the state-of-the-art radiodiagnostic techniques, the clarification of the pattern of the disease makes it possible to choose an optimal treatment policy and a surgical procedure and scope, to avoid anesthesia overload, and to decrease the probability of resurgery. Our observation is to demonstrate possible problems in the diagnosis of inflammatory myofibroblastic tumor of the lung in childhood and to recall again the algorithm of radiological approaches to detecting mediastinal and lung masses.

Metal-on-metal bearings have become more popular for hip arthroplasty in younger patients in the last 15 years. We present a review of the neurological consequences relating to such bearing surfaces illustrated by an appropriate case report. The mechanisms of increased metal ion production and pseudotumour formation are discussed. If unexplained neurology, hip/groin pain or a localised mass around the hip are present with a metal bearing hip then urgent referral to a specialist orthopaedic surgeon is warranted for consideration of exchange arthroplasty.

This report documents the evolution of a non-ruptured cranial fusiform aneurysm that underwent both spontaneous occlusion and regression. During this process, unique images of the aneurysm as a pseudotumoral-like mass were obtained. The pseudotumoral-like mass most likely reflected inflammation and secondary neovascularization within the aneurysm, supporting the theory that spontaneous aneurysmal healing involves an inflammatory process.

Pseudotumour is a rare but important complication of metal-on-metal hip resurfacing that occurs much more commonly in women than in men. We examined the relationship between head-neck ratio (HNR) and pseudotumour formation in 18 resurfaced hips (18 patients) revised for pseudotumour and 42 asymptomatic control resurfaced hips (42 patients). Patients in whom pseudotumour formation had occurred had higher pre-operative HNR than the control patients (mean 1.37 (sd 0.10) vs mean 1.30 (sd 0.08) p = 0.001). At operation the patients with pseudotumours had a greater reduction in the size of their femoral heads (p = 0.035) and subsequently had greater neck narrowing (mean 10.1% (sd 7.2) vs mean 3.8% (sd 3.2) p < 0.001). No female patient with a pre-operative HNR ≤ 1.3 developed a pseudotumour. We suggest that reducing the size of the femoral head, made possible by a high pre-operative HNR, increases the risk of impingement and edge loading, and may contribute to high wear and pseudotumour formation. As the incidence of pseudotumour is low in men, it appears safe to perform resurfacing in men. However, this study suggests that it is also reasonable to resurface in women with a pre-operative HNR ≤ 1.3.

Extramedullary hematopoiesis (EMH) is a systemic reaction to inadequate hematopoiesis. We report two exceedingly rare cases of EMH involving the paranasal sinuses. The first patient, a 30-year-old man, presented with a maxillary sinus mass. The lesion was excised by endoscopic surgery: definitive histology identified foci of EMH within an inflammatory fibromyxoid pseudotumor. The second case occurred in a 29-year-old man affected by intermediate beta-thalassemia. He was hospitalized with a diagnosis of sphenoid sinus mucocele secondary to an ethmoid lesion. The patient underwent endoscopic excision of the mass and drainage of the sphenoid mucocele. At definitive histology, a diagnosis of EMH was established. Herein, the presenting modalities, imaging profile, and treatment options of this rare EMH localization are reviewed., (Copyright (c) 2009 Elsevier Ireland Ltd. All rights reserved.)

Inflammatory pseudotumours occasionally occur after metal-on-metal hip resurfacing and often lead to revision. Our aim was to determine the severity of this complication by assessing the outcome of revision in these circumstances and by comparing this with the outcome of other metal-on-metal hip resurfacing revisions as well as that of matched primary total hip replacements. We identified 53 hips which had undergone metal-on-metal hip resurfacing and required revision at a mean of 1.59 years (0.01 to 6.69) after operation. Of these, 16 were revised for pseudotumours, 21 for fracture and 16 for other reasons. These were matched by age, gender and diagnosis with 103 patients undergoing primary total hip replacement with the Exeter implant. At a mean follow-up of three years (0.8 to 7.2) the outcome of metal-on-metal hip resurfacing revision for pseudotumour was poor with a mean Oxford hip score of 20.9 (sd 9.3) and was significantly worse (p < 0.001) than the outcome for fracture with a mean Oxford hip score of 40.2 (sd 9.2) or that for other causes with a mean Oxford hip score of 37.8 (sd 9.4). The clinical outcome of revision for pseudotumour was also significantly worse (p < 0.001) than the outcome of matched primary total hip replacements. By contrast, the outcome for fracture and other causes was not significantly different from that of matched primary total hip replacements (p = 0.065). After revision for pseudotumour there were three cases of recurrent dislocation, three of palsy of the femoral nerve, one of stenosis of the femoral artery and two of loosening of the component. Five hips required further revision. In three of these there was evidence of recurrent pseudotumour, and one is currently awaiting further revision. The incidence of major complications after revision for pseudotumour (50%) was significantly higher (p = 0.018) than that after revision for other causes (14%). The outcome of revision for pseudotumour is poor and consideration should be given to early revision to limit the extent of the soft-tissue destruction. The outcome of resurfacing revision for other causes is good.

Study Design: A retrospective review of 10 consecutive patients with a noninflammatory retro-odontoid pseudotumor., Objective: To examine the radiographic characteristics in patients with a retro-odontoid pseudotumor and to evaluate the efficacy of posterior fusion., Summary of Background Data: A retro-odontoid pseudotumor, a reactive fibrocartilaginous mass, is known to develop after chronic atlantoaxial instability; however, one-third of the reported cases showed no overt atlantoaxial instability. The pathomechanism for such "atypical" cases remains unclear, although altered cervical motion secondary to ossification of the anterior longitudinal ligament (OALL) or severe spondylosis has been implicated., Methods: We reviewed the charts and radiographs of 10 patients with a retro-odontoid pseudotumor who underwent surgery. Preoperative radiographs were evaluated for atlas-dens interval (ADI), presence of OALL, range of motion, and segmental motion adjacent to the atlantoaxial joint. Computed tomography was evaluated for degenerative changes of zygapophysial joints., Results: There were 6 men and 4 women. Atlantoaxial instability (ADI >4 mm) was observed in 2 patients. ADI was less than 3 mm in 5 patients. Frequent association of OALL (6 patients) and marked decrease in C2 to C7 range of motion (mean, 17.6 degrees ; range, 3 degrees-36 degrees ) were noted. Ankylosis of O-C1 was observed in 4 patients and C2 to C3 in 6. Severe degenerative change of C2 to C3 zygapophysial joint was observed in 4 patients. The patients underwent occipito-cervical fusion (9 patients) or direct removal of the pseudotumor (1 patient). Postoperative magnetic resonance imaging invariably demonstrated the mass regression., Conclusion: Retro-odontoid pseudotumors were not always associated with radiographic atlantoaxial instability. Our data indicate that extensive OALL and ankylosis of the adjacent segments are risk factors for the formation of the pseudotumor. Retro-odontoid pseudotumors may develop as an "adjacent segment disease" after altered biomechanics of the cervical spine, especially those in the adjacent segments. Posterior fusion was effective even in cases without radiographic atlantoaxial instability.

Inflammatory Myofibroblastic Tumor (IMT) is the recent name of Inflammatory pseudotumor which was in intermediate group of fibrous-origin tumor. The authors retrospectively reviewed such cases in Ramathibodi Hospital from January 2001 to December 2005. There were 115 cases of fibrous-origin tumor which was IMT in 17 cases. Nine cases occurred in the abdomen and only 3 of these had complete computerized tomographic (CT) imaging. One was hypodense liver mass with thick rim enhancement. Another one in the liver presented as a liver abscess which appeared as multiloculated hypodense mass with enhanced septum. The third case was a large malignant-looking retroperitoneal mass and having a small accompanying hepatic lesion which rapidly grew in the follow up study at nine months. IMT in the abdomen was scanty. The diagnosis was done with difficulty because of different signs and symptoms such as fever and palpable abdominal mass. The laboratory findings were nonspecific or within normal limits. Tissue biopsy was the way of definite diagnosis. We reported 3 cases of abdominal IMT with variable imaging findings that may lead to inappropriate treatment. Recognization of such findings will help achieve correct diagnosis.

We report a case of gastrointestinal histoplasmosis in a 45-year-old HIV positive man who was misdiagnosed as a case of colonic cancer. The patient presented with low-grade fever, pain in lower abdomen, anorexia and weight loss of six months duration. On examination a lump in the left iliac fossa was detected. Colonoscopy revealed stricture and ulcerated growth in the sigmoid colon. Radiological investigations suggested malignant/inflammatory mass in the sigmoid colon with luminal compromise. Patient was operated and ulcerated tissue was sent for histopathological examination, which revealed numerous intracellular, 2-4 microm, oval, narrow-based budding yeast cells suggestive of Histoplasma capsulatum. Subsequently, the patient developed fluffy opacities on X-ray chest. Examination of sputum revealed presence of acid-fast bacilli and yeast forms of H. capsulatum. Patient was started on amphotericin B but died on the seventeenth postoperative day. The diagnosis of histoplasmosis was made retrospectively. Atypical presentation and rarity of the disease led to this diagnostic pitfall. To the best of our knowledge this is the first report of gastrointestinal histoplasmosis presenting as colonic pseudotumour from India.

Inflammatory pseudotumor (IPT) is an uncommon benign disorder characterized by proliferation of spindle cells, inflammatory cells, and small vessels. The IPT of lymph nodes is a rare cause of lymphadenopathy that usually affects one or two nodal groups. We describe a 27-year-old male presenting with generalized lymphadenopathy, hepatosplenomegaly and fever for 1 year. Histologic examination of lymph node revealed few remnant lymphoid aggregates with marked sclerosis and numerous anastomosing blood vessels in lymph node parenchyma. Interspersed in between the fibrotic bands was a polymorphic infiltrate composed of lymphocytes, plasma cells, eosinophils, and immunoblasts. Also, many histiocytes, multinucleated giant cells some being Langhan's type and at places forming ill-defined granulomas were observed. The presence of granulomas and Langhan's type of giant cells can lead to a misdiagnosis of tuberculosis as was also done in the present case. It is thus not only important to be aware of this rare benign pathologic entity while dealing with a case of lymphadenopathy, but also consider it in the differential diagnosis of granulomatous disease.

Inflammatory myofibroblastic tumor is a recently characterized lesion, composed of exuberant myofibroblastic proliferation and an inflammatory component. Its etiology remains controversial, as to whether this represents a benign tumor with limited potential to recur or progress. Exaggerated response to trauma or infection has also been implicated. Only a few cases of laryngeal inflammatory myofibroblastic tumor have been described in English after it has been assigned the new name. The prototype lesion, inflammatory pseudotumor, has been best described in association with the lung but has also been reported involving various organs. We report 2 additional cases with a considerable variation in the presentation and histology of the lesion, thus expanding the morphological spectrum of the entity. Both lesions appeared aggressive in clinical presentation. One case had relatively more pleomorphic appearance and increased mitotic rate. Both lesions were surgically resected, and complete voice preservation was achieved. No postoperative complications or recurrence were noticed. This uncommon neoplasm may appear clinically as a large infiltrating mass and may be mistaken as a malignant growth. Conservative resection of the tumor may provide a cure with adequate voice preservation.

We report a case of a splenic inflammatory pseudotumor (myofibroblastic tumor) in a 43-year-old man with a 5-year history of chronic bronchitis and sleep apnea syndrome. The patient was hospitalized because of a screen-detected splenic mass lesion. His sputum cultures revealed Mycobacterium avium complexes on only one occasion. Imaging studies revealed a 7 cm solitary tumorous lesion, and differential diagnoses of splenic hamartoma, hemangioma, lymphoma, and angiosarcoma were obtained from the radiologist. A splenectomy followed by pathological investigations was performed. By histology, the lesion contained fibroblastic or myofibroblastic spindle cell proliferations, accompanied by variable degrees of inflammatory cell infiltration. Ziehl-Neelsen staining did not reveal acid-fast bacteria. Immunohistochemically, the fibroblastic or myofibroblastic spindle cells were positive for vimentin, human smooth muscle actin, and muscle actin, but negative for desmin, CD8, CD21, CD23, CD35, p80, Epstein-Barr virus LMP, and human herpesvirus type 8. The infiltrating lymphoid cells demonstrated a nonneoplastic pattern. The results of in situ hybridization for Epstein-Barr virus encoded RNA were negative. The postoperative course was uneventful and he has had no recurrence in 22 months. His sleep apnea syndrome and chronic bronchitis have resolved spontaneously since the splenectomy.

An inflammatory myofibroblastic tumor (IMFT) is a rare entity that can arise in a multiplicity of organs including the lung, liver, and at any location within the gastrointestinal tract. Typically, an IMFT presents as a localized mass with clinical symptoms dependent upon its site of origin. IMFTs pathologically resemble a neoplastic process but are theorized to arise from an unknown inflammatory event. We present a case of a midesophageal IMFT in a 12-year-old female.

Immune reconstitution inflammatory syndrome (IRIS) encompasses a variety of conditions that occur among HIV-infected patients in a temporal relationship with increases in CD4 cell count as a result of highly active antiretroviral therapy (HAART). Most conditions associated with IRIS are infectious. Malignancies, such as Kaposi's sarcoma, have also been reported. We report a case of sinusitis with presumptive inflammatory pseudotumor as a manifestation of IRIS that occurred 20 weeks after the initiation of HAART.

To verify the pathologic features, anaplastic lymphoma kinase (ALK) expression and biologic behavior of inflammatory myofibroblastic tumors (IMTs) of the central nervous system (CNS), we analyzed 10 cases of IMTs-CNS (8 cranial, 1 spinal, and 1 orbital). Our series of IMTs of the CNS showed a male predominance (male:female = 6:4) and a wide age range (10-60 years; mean age, 46.7 years). Lesion location also varied, but they were basically dura-based. Radiologically, they showed two patterns: isolated mass forming (n = 6) and an en plaque-like pattern (n = 4). Histopathologically, plasma cell granuloma (PCG)-like (n = 5) or fibrohistiocytic (FHC) variant (n = 5) was present. No correlation was found between the radiologic and histopathologic patterns. Spindle-shaped mesenchymal cells of IMTs expressed smooth muscle actin (SMA) in all cases. ALK expression was not found in our IMTs of the CNS. Late recurrence was found in 2 cases in different sites (20%). Pathologically, IMT-CNS could be subclassified into PCG-like and FHC. Immunostaining for SMA was found to helpfully discriminate myofibroblastic cells and to make a differential diagnosis. Although our cases did not show ALK immunoreactivity, some IMTs-CNS can recur, which suggests the neoplastic potential of these tumors. The rearrangement of the ALK gene in IMTs-CNS should be verified by an examination of more cases.

Inflammatory myofibroblastic tumor of the lung has often been reported but extrapulmonary cases are rare. Here we describe a case of inflammatory myofibroblastic tumor of the breast in a 60-year-old woman. This is only the eleventh case reported in the English language literature. The patient was free of disease 85 months after surgery.

Inflammatory myofibroblastic tumor (IMT) or inflammatory pseudotumor was initially recognized in the lung, and somewhat later, a similar-appearing pathological process was reported in the liver. Presently, this tumor has been described in virtually all major organs and extrapulmonary sites with a few exceptions. It was thought initially that the IMT was nonneoplastic and represented an aberrant inflammatory response despite its gross and microscopic features of a spindle cell neoplasm. The inflammatory hypothesis about the pathogenesis has been more readily accommodated in the lung than in the extrapulmonary sites of involvement. Some cases, however, were accompanied by the constitutional symptoms and signs of an inflammatory process, which resolved in most cases after surgical resection. There were some pathological aspects of the IMT that seemingly contradicted its purely inflammatory nature, including its potential for local recurrence; development of multifocal, noncontiguous tumors; infiltrative local growth; vascular invasion; and malignant transformation. These pathological features seemed to support the hypothesis that the IMT is a neoplastic process, which has been augmented by reports that these tumors have clonal characteristics. Other studies have suggested that IMTs of the liver and spleen are associated with the Epstein-Barr virus. From the diagnostic perspective, there are several potential difficulties that the pathologist may encounter in the examination of one of these tumors. Just as it was true 60 years ago, the potential for a pathological diagnosis of one or another type of spindle cell sarcoma has not diminished with time. Because these tumors have a predilection for children, embryonal rhabdomyosarcoma is another diagnostic temptation when an IMT presents in the bladder or other hollow viscus. The IMT should probably be regarded as a soft tissue-mesenchymal tumor with an indeterminant or low malignant potential, which is a somewhat indefinite but realistic prognostic category.

We report 51 cases of a previously undescribed tumor of the distal extremities that is often mistaken for an inflammatory or infectious process, Hodgkin's disease, or various sarcomas. These lesions developed in patients of all ages (range, 4-81 yr; median, 40 yr) and affected the sexes nearly equally (27 men, 24 women). They presented as a painless mass of the fingers (14 cases), hand (11 cases), wrist or arm (10 cases), toe or foot (8 cases), or lower leg (5 cases), usually within the subcutaneous tissues. Grossly, they were infiltrative, multinodular masses characterized by a dense chronic inflammatory infiltrate that merged with a stroma, which varied from densely hyaline to focally myxoid and contained sheets of short spindled to rounded epithelioid cells. Focally, the epithelioid cells were extremely large with bizarre, vesicular nuclei and macronucleoli resembling Reed-Sternberg cells or virocytes. Despite the level of atypia, mitotic activity was low. The tumor cells consistently expressed vimentin but lacked a variety of other mesenchymal, epithelial markers, e.g., S100 protein, desmin, actin, neuron-specific endolase, epithelial membrane antigen, HMB-45, CD34) and leukocyte markers (CD15, CD30, CD45). Keratin was noted focally and weakly in four cases and CD68 focally in six cases, the latter suggesting that the cells had acquired phagocytic properties. Immunostains for cytomegalovirus were negative. Polymerase chain reaction for Epstein-Barr virus showed amplification levels consistent with latent infection in 4 of 10 cases, but no cases showed levels consistent with active infection. All of the bacterial and viral cultures were negative. Follow-up information was available in 27 cases. Recurrences developed in six patients (interval, 15 mo-10 yr), but there were no metastases or tumor-related deaths. In one patient, progressive proximal extension up the arm was noted. Although the most common submitting diagnosis was that of an inflammatory or infectious process, the negative studies for infectious agents, clinical behavior with local recurrences, immunophenotypic profile, and cytologic atypia support the idea that these are unusual mesenchymal neoplasms with at least the potential for local recurrence. It remains to be investigated whether with time these lesions will prove to have metastatic potential.

Inflammatory pseudotumor (IPT) is an uncommon benign neoplasm of uncertain etiology that classically has been associated with the lung, where it is generally asymptomatic. In recent years, IPT has been increasingly recognized in other sites. Hepatic, abdominal, and pelvic IPTs produce a spectrum of nonspecific symptoms including fever, malaise, anemia, and weight loss. Because prolonged fever is a prominent feature of extrapulmonary IPT, patients with this condition may first come to the attention of specialists in infectious diseases. We describe an illustrative case of pelvic IPT and discuss its presentation, diagnosis, and treatment; we also suggest that infectious disease specialists should be familiar with this entity as a possible diagnosis for patients with fever of unknown origin.

Background: Unusual lesions composed of fibrous tissue, lymphocytes, histiocytes, and plasma cells, called inflammatory pseudotumors (IPT), are being increasingly recognized in many organs and tissues. A hepatic IPT extending into the inferior vena cava has never been reported before to the authors' knowledge. The patient in this study underwent liver resection with cardiopulmonary bypass and circulatory arrest to excise the IPT., Methods: The tissue was studied extensively using histologic, immunohistologic, flow cytometric, and gene rearrangement analysis and electron microscopic methods., Results: On gross examination, the large hepatic tumor resembled a malignancy invading the vena cava. Microscopically, a mixture of T-lymphocytes, B-lymphocytes, and plasma cells were scattered throughout the tumor. DNA flow cytometry did not reveal aneuploidy suggestive of neoplasia. Genetic analysis of the immunoglobulin and T-cell receptor genes did not detect evidence of clonal expansion of B-cells or T-lymphocytes., Conclusions: This experience with the vascular invasive and biliary obstructive nature of IPT and the difficulty in diagnosing it before or during surgery underscores the potentially adverse impact of this lesion on patients. The authors believe that an aggressive approach should be taken when evaluating and treating hepatic masses, even though they may later be confirmed as being IPT.

Inflammatory pseudotumor of the liver is a rare benign lesion that usually has been discovered at laparotomy and treated by hepatic resection. We report a case of hepatic pseudotumor that was treated without surgery and that subsequently spontaneously resolved. Hepatic pseudotumor occur in all age groups, but most commonly in middle-aged adults, with a 3.5:1 male predominance. Presenting symptoms are 1 or 2 months of fever (66%), abdominal pain (51%), and weight loss (21%). Most often, the lesions are solitary encapsulated tumors composed of whorled laminated fibrous stroma and chronic inflammatory infiltrate. Our report provides documentation of spontaneous resolution of a hepatic pseudotumor.