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Perforation of a peptic ulcer into the ventricle is uncommon, and the definitive diagnosis is difficult in living patients. We herein report a case of perforation of a peptic ulcer in a hiatal hernia into the left ventricle with systemic air and food embolism. This is the first case report of the perforation diagnosed by computed tomography and confirmed by autopsy. Computed tomography was useful for the diagnosis of perforation into the ventricle.

In the present study, we investigated the correlation between the presence of occult neoplastic cells (ONCs) in lymph node sinuses and recurrence/metastasis of stage II/III gastric cancer in 164 patients who underwent radical curative resection. We calculated the five-year relapse-free survival rate (5Y-RFS) and five-year overall survival rate (5Y-OS) of the ONC(+) and ONC(−) groups. The 5Y-RFS was 71.4% in the ONC(−) group and 47.5% in the ONC(+) group (P=0.003). The 5Y-OS was 68.8 and 48.4%, respectively (P=0.008). ONCs were found in 34.8% of stage II patients and were also detected in 66.7% of stage III patients. For distinguishing between the recurrence and non-recurrence groups, the sensitivity of ONC(+) was 64.5% (40/62; P=0.003), the positive predictive value (PPV) was 49.4% (40/81), the specificity was 59.8% (61/102) and the negative predictive value (NPV) was 73.5% (61/83). This high sensitivity indicates that ONC positivity may be a significant indicator for high-risk patients in the early postoperative period, and a lack of ONCs may be a useful indicator for identifying low-risk patients, as patients without ONCs had a high NPV.

Oral inverted ductal papilloma is a rare, benign epithelial tumor that exhibits an endophytic growth pattern and is found almost exclusively in the minor salivary glands. We report on a case of inverted ductal papilloma in the buccal mucosa. We also performed an immunohistochemical study. The tumor cells were positive for cytokeratin and epithelial membrane antigen, while negative for calponin, S-100 protein, α-SMA, vimentin, and desmin. This result indicated that the lesion arises from the excretory duct near the oral mucosal surface but not the myoepithelial cells. In addition, Ki-67 labeling index of 3.96% indicated the low level of proliferation.

We report a case of a ruptured isolated true external iliac artery aneurysm (EIAA). A 78-year-old woman was admitted to our institution in a shock state after the sudden onset of severe pain in the right hypogastric region. A pulsating mass was found in her right lower abdomen. Computed tomography (CT) with contrast medium showed an isolated EIAA, 40 mm in diameter, with a massive retroperitoneal hematoma. She underwent emergency resection of the aneurysm and reconstruction of the affected artery, without any complications. Histological examination confirmed a true aneurysm caused by cystic medial necrosis (CMN). She had no ocular, cardiac, or orthopedic abnormalities. We review the literature on isolated true aneurysms of the external iliac artery, which are extremely rare, and discuss their clinical manifestations.

✓Only 4 cases of gas-filled intradural cysts of the spine have been reported previously. All cysts were due to intradural herniation of a gas-containing disc. The authors report 2 additional patients with gas-filled intradural cysts that migrated into the nerve root of the cauda equina. After surgical treatment their severe leg pain completely resolved.

症例は76歳の男性で, 2001年10月に検診で胃の異常陰影を指摘され, 精査加療目的で当科を紹介された. 血液検査では腫瘍マーカーは正常であったが可溶性IL-2レセプターは926U/mlと高値であった. 上部消化管造影, 内視鏡検査では前庭部に2型の腫瘍を認めた. 生検では悪性リンパ腫が疑われた. 以上から, 胃悪性リンパ腫を疑い2001年12月胃全摘, 脾摘術を施行した. 病理組織学的, 免疫組織学的検査で胃小細胞癌と診断した. 術後CPT-11による化学療法を施行した. 2003年8月の腹部CTで肝S7に22mm大の腫瘍を認め肝転移が疑われた. その他全身に異常を認めなかったため2003年11月, 肝S7S8部分切除術を施行した. 病理組織学的に肝腫瘍は胃切除組織と同様であり胃小細胞癌の肝転移と診断した. 肺転移の疑いがありVP-16による化学療法を施行中であるが胃切除から3年, 肝切除から1年1か月の現在生存中である.

症例は46歳,男性.右下腹部痛を自覚し,当院内科を受診,腹部超音波検査で腹腔内腫瘤を指摘された.触診上,臍部を中心に約10cm大の圧痛を伴った弾性軟な腫瘤を触知した.腹部CT検査で腫瘤は胃前庭部,小腸と密に接していた.上部消化管内視鏡検査で胃,十二指腸に異常はなかった.血管造影検査で右胃大網動脈から栄養されており大網GISTの疑いで手術を施行した.開腹すると大網内に20cm大の腫瘤を認めた.小腸とは連続性がなく胃前庭部大彎に0.5cmほど連続しており,腫瘍とともに胃部分切除を行った.病理組織検査で腫瘍は紡錘形細胞からなり,胃壁の固有筋層内に一部浸潤していた.免疫染色でc-kit(+), CD34(+), S-100(+), desmin(-), SMA(-)であり, GISTと診断した.腫瘍の主座は大網であったが大網原発GISTの本邦報告は23例と少なく胃壁外性発育のGISTとの鑑別が問題と考えられた.

We describe a dorsalis pedis artery true aneurysm due to atherosclerosis. A 61-year-old woman had a pulsatile and painful tumor on the right dorsal part of the foot, and magnetic resonance imaging revealed an aneurysm of the dorsalis pedis artery. Resection of the aneurysm was completed without complications. Pathologic analysis showed true aneurysm due to atherosclerosis. We review the literature on true aneurysm of the infrapopliteal arteries, including the dorsalis pedis artery, and discuss the clinical presentation and surgical management.

For the treatment of patients with metastatic breast cancer by humanized anti-human epidermal growth factor receptor type 2 (HER2) antibody (trastuzumab), it is important to evaluate HER2 status adequately. This article overviews developments of basic and clinical research for HER2 gene, and introduces general agreement with the evaluation system of HER2 overexpression with several commentaries from the aspect of histochemistry.

Proximal ulnar artery aneurysms, including pseudoaneurysms, have not been described in the English literature. We report a nontraumatic pseudoaneurysm of the proximal ulnar artery with eosinophilia in a 54-year-old man. Radial, coronary, and hepatic artery aneurysms associated with eosinophilia in idiopathic hypereosinophilic syndrome or allergic granulomatous angiitis (Churg Strauss syndrome) have been reported. Although it is unclear in the present case whether eosinophilia was associated with the pseudoaneurysm of the ulnar artery, eosinophil infiltration into the aneurysmal wall may have influenced vascular injury as the cause of the pseudoaneurysm formation.

A 73-year-old male with diabetes mellitus had been treated with insulin for six years. He developed a solid mass on his left lateral of the abdomen at the insulin injection site. A firm subcutaneous mass with dark-red erythema was overlaid by dark-brown keratinized plaques. On histological examination of the mass, keratin proliferation and epidermal papilloma were observed. There were four previously reported cases of acanthosis nigricans that were considered to be caused by continuous injections of insulin. Using immunohistochemistry, in our case the findings were positive in the basal epithelial and prickle cell layers when the patient's lesion was dyed with insulin-like growth factor (IGF)-1 antibody. The coexistence of dermal IGF-1 receptor and acanthosis nigricans found in our patient has not been reported previously, to our knowledge.

Peripheral ameloblastoma (PA) is a rare extraosseous odontogenic tumor with histological characteristics similar to those of the common intraosseous ameloblastoma. Two questions regarding PA remain: its histogenic origin and how to differentiate between PA and intraoral basal cell carcinoma. We describe a patient with PA. The result of immunohistochemistry showed cytokeratin (CK) 7-, CK14+, CK19+, AE1/AE3+, CAM5.2-, 34 β E12+, epithelial membrane antigen-, Ber-EP4-, p53-, p63+, and low Ki-67, that was similar to those of 4 cases of intraosseous ameloblastoma. Our results suggest that a PA originates from odontogenic epithelial remnants, rather than from the oral epithelium.

The differential diagnosis of a buccal soft tissue mass containing calcified bodies includes a phlebolith associated with a vascular lesion, such as a hemangioma with a calcified intravascular thrombus, and diseases such as sialolithiasis, traumatic myositis ossificans, calcified acne lesion, neoplasm, and calcified lymph nodes, including tuberculosis. The appearance of the calcified bodies on plain radiographs may help to differentiate these entities. Computed tomography, magnetic resonance imaging, and ultrasonography are also useful for differentiating the soft tissue lesions. We report a 17-year-old girl with a small mass containing a calcified body in the anterior portion of the masseter muscle. The mass was resected surgically and evaluated histologically, confirming the diagnosis of phlebolith. We also discuss the differential diagnosis of a buccal soft tissue mass containing calcifications and suggest that the immunolocalization of CD31 at capillaries in the mass may help to diagnose as a phlebolith.

A 62-year-old male patient underwent endoscopic mucosal resection (EMR). Additional hybrid 2-port hand-assisted laparoscopic surgery (HALS) (Mukai's operation) was performed for early rectal cancer located at the distal border of the rectum/below the peritoneal reflection (Rb) region [SM massive invasion/ly+/vertical margin (VM)X] via a small transverse incision, approximately 55 mm long, at the superior border of the pubic bone. After the pelvic floor muscles were dissected by laparoscopy-assisted manipulation, transanal subtotal intersphincteric resection (ISR) was performed under direct vision, securing a margin of more than 15 mm distal to the EMR scar. Partial external sphincteric resection (ESR) was also performed to obtain an adequate VM at the posterior region of the EMR scar. After bowel reconstruction, the layers were sutured transanally and a temporary covering colostomy was created. The resected specimen contained no residual tumor cells without lymph node metastasis. At 3 months after the operation, digital examination revealed good tonus of the anal muscles without stricture. The patient is currently undergoing rehabilitation of his anal sphincter muscles in preparation for the colostomy closure. In conclusion, subtotal ISR combined with partial ESR may decrease the need to perform Miles' operation for T1/2 stage I rectal cancer located at the distal border of the Rb region.

This report concerns a case of solitary fibrous tumor (SFT) for which surgical resection was performed using a retroperitoneal approach. A 41-year-old man was referred to our hospital with urinary retention. Abdominal ultrasound sonography (US) and computed tomography (CT) showed a hypervascular mass lesion in the pelvis. Transrectal biopsy showed SFT. Surgical resection was carried out using a retroperitoneal approach and preserving the neural network related to urinary and erectile functions. Based on immunohistochemical findings, the tumor was diagnosed to be malignant SFT in the pelvic cavity. Urinary function improved post-operation. There was no change to IIEF-5 and it continued to function well. The patient showed no sign of recurrence 12 months after surgery and required no additional therapy.

The 5-year relapse-free survival rate (5Y-RFS) and the 5-year overall survival rate (5Y-OS) were calculated for 972 patients (stage I, 206 patients; stage II, 396 patients; stage III, 370 patients). We divided the stage III group into 259 patients with IIIa/N1 disease (≤3 positive nodes) and 111 patients with IIIb/N2 disease (≥4 positive nodes) according to the Japanese classification. The IIIa/N1 and IIIb/N2 categories were each subdivided into T1/2 (stage IIIa, 45 cases; IIIb, 9 cases) and ≥T3 (stage IIIa, 214 cases; IIIb, 102 cases) according to the TNM classification, and 5Y-RFS and 5Y-OS were compared between each subcategory and each group. The 5Y-RFS/5Y-OS values calculated for each stage were as follows: stage I, 94.0/90.7%; stage II, 80.5/81.1%; stage III, 63.5/65.7%. When stage IIIa was compared with IIIb, we obtained 67.9/72.0% for stage IIIa and 53.6% (p=0.001)/50.4% (p

Kartagener's syndrome is a rare inherited disorder with a triology of symptoms (bronchiectasis, sinusitis and situs inversus) and is also associated with abnormalities of the cilia of the respiratory epithelium. Lung cancer arising in Kartagener's syndrome is very rare and to date only 5 cases have been reported in the English and Japanese literature. We report on a case of a 65-year-old Japanese male Kartagener's syndrome patient with squamous cell carcinoma of the lung. A left pneumonectomy was performed and no recurrence was found within 2 years.

Lymph nodes from patients with colorectal cancer were immunohistochemically stained for cytokeratin in order to investigate the relationship between the presence of occult neoplastic cells (ONCs) and recurrence/metastasis. A total of 78 patients with stage II/Dukes' B colorectal cancer were divided into two groups. The first group consisted of 18 patients who had developed recurrence/metastasis (recurrence group) and the other one of 60 patients who had survived without recurrence (non-recurrence group). The presence of ONCs was compared between the two groups with respect to i) single cells (≥3 floating ONCs), ii) clusters of cells (≥1 floating aggregates of 2-20 ONCs), and iii) single cells + clusters. When single cells were detected, the sensitivity for recurrence was 55.6% (10/18), the positive predictive value (PPV) was 30.3% (10/33), the specificity was 61.7% (37/60, p=0.195), and the negative predictive value (NPV) was 82.2%(37/45). For the clusters, the sensitivity was 55.6% (10/18), PPV was 37% (10/27), specificity was 71.7% (43/60, p=0.033), and NPV was 84.3% (43/51). With single cells + clusters, the values were 55.6% (10/18), 43.5% (10/23), 78.3% (47/60, p=0.006), and 85.5% (47/55), respectively. These results suggest that the detection of single cells + clusters has a high specificity and NPV, and indicates a low risk of recurrence/metastasis in patients with stage II colorectal cancer.

Lymph nodes from patients with colorectal cancer were immunohistochemically stained for cytokeratin in order to investigate the relationship between the presence of occult neoplastic cells (ONCs) and recurrence/metastasis. A total of 78 patients with stage II/Dukes' B colorectal cancer were divided into two groups. The first group consisted of 18 patients who had developed recurrence/metastasis (recurrence group) and the other one of 60 patients who had survived without recurrence (non-recurrence group). The presence of ONCs was compared between the two groups with respect to i) single cells (≥3 floating ONCs), ii) clusters of cells (≥1 floating aggregates of 2-20 ONCs), and iii) single cells + clusters. When single cells were detected, the sensitivity for recurrence was 55.6% (10/18), the positive predictive value (PPV) was 30.3% (10/33), the specificity was 61.7% (37/60, p=0.195), and the negative predictive value (NPV) was 82.2%(37/45). For the clusters, the sensitivity was 55.6% (10/18), PPV was 37% (10/27), specificity was 71.7% (43/60, p=0.033), and NPV was 84.3% (43/51). With single cells + clusters, the values were 55.6% (10/18), 43.5% (10/23), 78.3% (47/60, p=0.006), and 85.5% (47/55), respectively. These results suggest that the detection of single cells + clusters has a high specificity and NPV, and indicates a low risk of recurrence/metastasis in patients with stage II colorectal cancer.

During the initial emergency operation, a temporary loop colostomy (TLC) was constructed at the oral border of the region for subsequent radical resection. Then, radical surgery was performed by hybrid 2-port HALS (Mukai's operation) using the TLC as the hand access site. Left hemicolectomy was done in three patients, sigmoidectomy in two cases, low anterior resection in one case, and Hartmann's operation in one case. Radical surgery was not done in one patient with multiple distant metastases. The mean operating time was 3 h and 7 min (ranging from 1 h and 55 min to 3 h and 47 min), the mean blood loss was 146.4 ml (7-354 ml), the mean duration from TLC to HALS was 11.3 days (8-16 days), and the mean hospital stay after HALS was 13.9 days (9-20 days). Mild wound infection occurred postoperatively in 2/7 patients and ileus occurred in one patient. However, there was no anastomotic leakage/stricture or conversion to conventional laparotomy. These results suggest that 2-stage treatment (Mukai's method with Mukai's operation) is also applicable to large obstructing left colon or rectal cancers. This method is safe, less invasive, and achieves excellent results, including a good cosmetic outcome.

Malignant variants of ameloblastoma include metastasizing ameloblastoma, which microscopically appears benign but has metastasized and ameloblastic carcinoma that exhibits malignant histopathologic features. Ameloblastic carcinoma is classified into 2 types: a primary odontogenic malignancy and a secondary type resulting from malignant transformation of ameloblastoma. Most secondary ameloblastic carcinomas result from malignant transformation of a primary lesion after repeated postsurgical recurrences. Therefore it is rare to find an untreated secondary type presenting with histologic features of malignant transformation from an earlier benign lesion. We experienced a rare case of ameloblastic carcinoma, secondary type which might arise in an untreated ameloblastoma. The mechanism by which a preexisting benign ameloblastoma goes through a malignant transformation is also described.

Lung cancer is one of the most common malignant diseases in the world, and its prognosis is generally poor. Cancer and metastasis involve numerous biological steps, including angiogenesis in both the primary and metastatic sites. Although various molecules that are involved in both tumor neovascularization (angiogenesis) and invasion have been identified, little is known about how these molecules interact in cancerous microenvironments. We previously reported that the gene expressions of some factors associated with vascularization correlated with the prognosis of non-small cell lung cancer (NSCLC). In this study, we performed multivariate analysis of the mRNA levels of 10 selected genes [VEGF-A, VEGF121, VEGF165, VEGF189, S100A4, E-cadherin, Thrombospondin (TSP)-1, TSP-2, matrix metalloproteinase (MMP)-2, and MMP-9] in 130 NSCLC specimens using the real-time quantitative reverse transcription-polymerase chain reaction. Spearman's rank correlation test was used to determine the co-expression patterns. The analysis demonstrated highly significant co-expressions (P

Only 4 cases of gas-filled intradural cysts of the spine have been reported previously. All cysts were due to intradural herniation of a gas-containing disc. The authors report 2 additional patients with gas-filled intradural cysts that migrated into the nerve root of the cauda equina. After surgical treatment their severe leg pain completely resolved.

A case of atypical benign fibrous histiocytoma is reported. A 62-year-old Japanese female visited our clinic because of an asymptomatic solitary lesion on the skin of the left leg. Physical examination revealed a polypoid mass lesion (2.5 x 2.3 x 1.8 cm) with central erosion. The lesion began with a 1 mm-sized papule and slowly enlarged over the 20 years. Clinical diagnosis was a malignant tumor such as dermatofibrosarcoma protuberans, atypical fibroxanthoma or adnexal tumors. Biopsy of the polypoid lesion was carried out. Histopathological examination revealed a polypoid lesion consisting of proliferation of fibroblast-like spindle cells in the dermis. Large atypical cells with pleomorphic nuclei were occasionally observed but mitotic figures were rare. From immunohistochemical results (CD68, Factor-XIII, MIB-1 labeling index), we diagnosed this case as "atypical benign fibrous histiocytoma (ABFH)". Clear distinction has not been made between ABFH, a variant of benign fibrous histiocytoma, and atypical fibroxanthoma, which is a variant of malignant fibrous histiocytoma. Here we report a case of ABFH with a diagnosis of the neoplasm.

A case for primary gastrointestinal stromal tumor (GIST) is described with reference to its ultrastructural characteristics and mutation within the exon 11 of c-kit gene. A forty-seven years old woman complaining of dysphasia was examined by endoscopy, which depicted a submucosal tumor (70 mm in diameter) with ulcerations at the fundus of the stomach. Histopathologically, the tumor cells had large nuclei and eosinophilic cytoplasm and were frequently during mitosis phase. The tumor cells were immunopositive for KIT, CD 34 and vimentin, suggesting their fibroblast-like characteristics. In contrast, desmin and S-100, a smooth muscle and an enteroglial marker, were not immunopositive within the cells. At least 30 % of the tumor cells possessed MIB-I and 20 % of them possessed p53, which are compatible with fast development of the tumor. By electron microscopy, the tumor cells possessed large oval nuclei, abundant mitochondria, caveolae and smooth endoplasmic reticulums, while no gap junctions were seen on the cells: The tumor cells thus possessed interstitial cells-like characteristics at least in part. DNA mutation search for the tumor cells however realized no gain-of-function mutation within the exon 11 of the c-kit gene, suggesting existence of other mechanism for neoplasmic growth of the tumor cells classified as gastrointestinal stromal tumors.

The aim of the present study was to clarify differences in genetic events between primary breast cancers and asynchronous metastatic/recurrent lesions, by examining HER2 gene amplification and p53 mutation. The subjects were 44 breast cancer patients with asynchronous metastasis or recurrence. Synchronous metastases were excluded. HER2 overexpression and gene amplification were examined using immunohistochemistry and fluorescent in situ hybridization (FISH). P53 point mutation was examined by immunohistochemistry, laser-captured microdissection, PCR-single-strand conformation polymorphism, and a direct sequencing method. Immunohistochemistry showed that, for HER2, p53, ER and PgR, discordance rates between primary and recurrent tumor were 2 (4.5%), 1 (2.3%), 7 (15.9%) and 10 (22.7%), respectively. Two primary tumors with discordant HER2 overexpression were composed of at least two populations of carcinoma cells, with and without HER2 gene amplification. Distribution of HER2 gene amplification was consistent with protein overexpression. Corresponding recurrent tumors consisted of carcinoma cells without HER2 gene amplification. Of 6 recurrent tumors in which the primary carcinoma had a p53 point mutation, 3 tumors had identical mutations, 1 tumor had a different point mutation, and 2 tumors had no mutation. It was suspected that the latter 3 recurrent tumors comprised a minor component of the primary tumor. In the present study, we examined a large series of asynchronous recurrent tumors. A limited number of these tumors showed discordance between primary and recurrent tumors. Detailed observations revealed that cell populations present in recurrent tumors were also present in the primary tumors, although they comprised a minor component of the primary tumor. Heterogeneity of the primary tumor apparently contributed to discordance.

We report a rare case of minute (5 mm x 4 mm) mixed ductal-endocrine carcinoma of the pancreas with predominant intraductal growth. A 34-year-old Japanese man was admitted because of elevated serum pancreatic enzymes. Endoscopic retrograde pancreatography revealed an unidentified material of 18 mm within the main pancreatic duct. Stone or parasite with acute pancreatitis was suspected clinically, and the biopsy revealed malignant cells positive for CA19-9, carcinoembryonic antigen (CEA) and synaptophysin. No apparent tumor was identified in the pancreas by various imaging techniques. Resection of pancreatic body and tail was performed. Grossly, the main pancreatic duct in the pancreatic body was occluded by as much as 20 mm. The pancreas had minute carcinoma of 5 mm x 4 mm just around the occluded main pancreatic duct. The tumor cells invaded the main pancreatic duct and spread within it as long as 20 mm. Histologically, the carcinoma had biphasic pattern; one was ductal carcinoma with tubular formations and another was carcinoma with neuroendocrine features. These two elements were admixed, and the ductal element comprised 30% while the endocrine element comprised 70%. The ductal element was immunoreactive for cytokeratins, CEA and CA19-9, while the endocrine element was immunoreactive for chromogranin A and synaptophysin. No immunoreactivity for pancreatic enzymes was noted. Ultrastructural observations showed dense core granules and no zymogen granules. Our case is unique clinically in that the tumor manifested as an intraductal material and no apparent tumor was found by imaging modalities, and pathologically in that the tumor was rare mixed ductal-endocrine carcinoma and the tumor was very small and mainly grew within the main pancreatic duct.

A-25-year-old man was admitted because of a painless tumor of the scrotum. The patient denied a history of exogenous material injection and trauma in the scrotum. Physical and radiological examination revealed a mass in the scrotum, and blood laboratory tests showed no significant findings except for mild eosinophilia (5.6%). Resection of the mass was performed. The mass was isolated and located in the subcutaneous tissue of the scrotum. The mass was rectangular and symmetrical, and measured 65 x 45 x 15 mm. Histologically, the mass was composed of adipose tissue with fibrosis. Many epithelioid granulomas with multinucleated giant cells of foreign body and Langhans' types and heavy infiltrates of lymphocytes and eosinophils were recognized. Characteristically, the lesion showed broad coagulative and lytic necrosis. Congestion and edema suggestive of ischemia were seen in some areas. Special stains for acid-fast bacteria, gram-positive bacteria and fungi failed to detect any microorganisms. Polymerase chain reaction for mycobacterium tuberculosis revealed no reaction products. Immunohistochemically, the majority of lymphocytes were CD45RO-positive T cells, and S-100 protein-positive cells and CD68-positive macrophages were scattered in small amounts. The appearances were typical for sclerosing lipogranuloma except for the necrosis. Although the pathological mechanism of the broad necrosis is unclear, the necrosis might be the result of ischemia. Our case suggests that primary sclerosing lipogranuloma of the scrotum might show broad necrosis, and that T-cell-mediated immune response might play a part in the formation of lipogranuloma.

A case of sarcomatoid carcinoma of the renal pelvis is reported. A 72-year-old male was admitted with a chief complaint of right flank pain. Clinical imaging studies revealed marked dilation of the right renal pelvis caused by a tumor at the pyeloureteric region. Right nephrectomy was performed in June 1999. The 8.4 × 6.5 cm tumor was grossly polypoid in appearance and protruded into the renal pelvis. Histologically, sarcomatoid spindle cells predominated over the carcinomatous component (mainly transitional cell carcinoma, partly associated with squamous cell and adenocarcinoma components). Osteoclast-like CD68-positive multinucleated giant cells were scattered. The sarcomatoid component was immunoreactive for both cytokeratin and vimentin. Sarcomatoid cells negative for cytokeratin were also noted. In both the sarcomatoid and carcinomatous components, nuclear overexpression of p53 oncoprotein was confirmed. The histogenesis of sarcomatoid carcinoma of the renal pelvis is discussed.