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Sinonasal renal cell-like adenocarcinoma (SRCLA), which is an extremely rare but established entity, belongs to the non-salivary gland type of low-grade adenocarcinomas arising from the sinonasal tract. We report a case of high-grade SRCLA. The patient was a 63-year-old Japanese male, who complained of nasal obstruction. Histologically, the tumor exhibited solid nests and sheet-like structures composed of atypical clear or eosinophilic cells with central necrosis. The tumor cells contained periodic acid Schiff-positive glycogen. Immunohistochemically, they were positive for cytokeratin (CK)7, CD10, carbonic anhydrase (CA)-IX, the epidermal growth factor receptor (EGFR), mucin 1, and cancer antigen 125, whereas they were negative for CK20, caudal type homeobox 2, CK5/6, p40, vimentin, S-100, a renal cell carcinoma marker, paired box gene 8, and the human epidermal growth factor receptor 2. Both local recurrence and late lymph node metastases arose in this case. Therefore, the tumor was considered to be clinically aggressive and was diagnosed as a high-grade SRCLA. Immunostaining of CD10 and CA-IX was very diagnostically useful. Although 14 cases of SRCLA have been reported previously, all of them involved low-grade malignancies, and no descriptions of their EGFR statuses were provided. This is the first report about a high-grade SRCLA exhibiting EGFR overexpression.

The recent recognition of concept of perivascular myoid cell (PMC) phenotype and perivascular epithelioid cell (PEC) phenotype has changed the concept of angiogenic tumors, in particular “hemangioperycytoma” (HPC)-like tumors. The PMC concept has yielded myopericytoma, myofibroma, myofibromatosis, angioleiomyoma, and glomus tumors, while the PEC concept that shows melanocytic lineage has given rise to PEComa, clear cell sugar tumors, angiomyolipoma, and lymphangiomyomatosis. Here, the author reports a case of myopericytoma of soft tissue (thigh) occurring in a 47-year-old man. The patient had noticed the thigh tumor 4 years before, and was admitted. The tumor was located in subcutaneous tissue, was encapsulated, and measured 4 × 3 × 3 cm. Total excision was performed. Grossly, the tumor is a soft reddish encapsulated tumor with very well demarcation. Histologically, the tumor showed typical HPC-like features with focal nodular proliferation of HPC-like tumor cells. Immunohistochemically, the vasculatures were positive for vimentin, CD31, CD34, and factor VIII-related antigen. In contrast, the HPC-like tumor cells were positive for vimentin, α-smooth muscle antigen, h-caldesmon, bcl-2, and factor XIIIa, but negative for cytokeratins, desmin, CD31, CD34, factor VIII-related antigen, S100 protein, melanosome, CD99, and KIT. Ki-67 labeling was 15%, and p53 was mildly positive. The overall features were those of myopericytoma. The patient is now alive without recurrence 5 years after the operation. A brief literature review and differential diagnosis were made.

Angiosarcoma (AS) showed diverse morphologies from well formed malignant vasculatures to poorly differentiated tumor with only a few clues of endothelial differentiation. Herein reported are two cases of AS without primitive vasoformative channels (VC). They showed, instead, a very few foci of intracytoplasmic vacuoles (ICV) that mimicked liposarcoma. The two cases were found in 12 cases of AS in computer database. Both are men, 57 and 68 years. One is cutaneous (foot) AS and another is soft tissue (thigh) AS. The largest diameter of cutaneous AS was 5 cm, and that of soft tissue AS 9 cm. The prognosis of both patients was poor; both died of metastases 4 and 6 years after initial presentation. In both cases, hematoxylin and eosin (HE) diagnosis was difficult because there were no VC, and most of the tumors were composed of primitive mesenchymal tissues. In both cases, however, a few very tiny foci consisting of ICV were seen. At first, the author considered them as mucins or fat, and suspected liposarcoma. In fact, they were pseudolipoblasts. Several mucin stains showed no mucins, and fat stains of frozen sections of formalin fixed tissue were negative for fat. Immunohistochemically, the vacuoles were positive for factor VIII-related antigen (F-VIII-RA), Ulex lectin, CD31, CD34, vimentin, p53 and Ki-67 (labeling index = 64% and 75%), but negative for various types of cytokeratins (CK), EMA, CEA, CA19-9, CD45, smooth muscle actins, S100 protein, myoglobin, HMB-45, Melan A, NCAM, and NSE. F-VIII-RA is specific and Ulex lectin and CD31 are relatively specific for endothelium. Therefore, the pathological diagnosis of AS could be made by the combined histologic features (ICV) and Immunohistochemical positivity of F-VIII-RA, Ulex lectin, and CD31. Thus, it appeared that the ICV may be the only clue of poorly differentiated or undifferentiated AS. In such undifferentiated cases, combined observations of meticulous histologic observations (intracytoplasmic lumens and ICV) immunohistochemistry of F-VIII-RA, Ulex lectin, and CD31 may be helpful in the diagnosis of poorly differentiated and undifferentiated AS. Electron microscopic observations were not done in the present study.

The author reports herein the fourth case of rare clear cell adenocarcinoma (CCA) of ureter. The present case is the first of ureter CCA with extensive immunohistochemical examination. The patient is a 61-year-old man. The CCA was composed of malignant cells with very clear ample cytoplasm with occasional glandular formations. No apparent hobnail cells were seen. The tumor cells were seen to invade the adventitia. No carcinoma in situ was seen in the surrounding urothelium. A lymph showed metastasis. Histochemical stains revealed that the clear cytoplasm was due to glycogen not mucins or lipids. Immunohistochemically, tumor cells were positive for cytokeratin (CK) AE1/3, CK CAM5.2, CK34BE12, CK8, CK18, EMA, CEA, CA19-9, p53, platelet-derived growth factor-α (PDGFRA), MUC-1, and Ki-67 (labeling index = 26%). The tumor cells were negative for CK5/6, CK7, CK14, CK19, CK20, NSE, p63, vimentin, S100 protein, α-smooth muscle actin, c-erbB2, chromogranin, synaptophysin, KIT (CD117), CD56, CDX-2, MUC2, MUC5AC, MUC6, CD10 and RCC markers.

Herein reported is an extremely rare case of primary MALT lymphoma of cerebral parenchyma. A 79-year-old man presented with paresis. Imaging modalities identified a tumor measuring 3 cm in diameter in right cerebral parenchyma. An operation completely resected the tumor. Macroscopically, the tumor was well defined, but showed mild infiltrative features. Histologically, the tumor showed proliferation of small atypical lymphocytes separated by fibrous septae with AL amyloid depositions. No apparent plasma cell differentiation was seen. The tumor cells showed monotonous appearances with hyperchromatic nuclei but without nucleoli and nuclear indentations. Immunoblastic cells were scattered. Immunohistochemically, tumor cells were positive for vimentin, CD45, CD20, CD79α, bcl-2, CD3 (focal), CD45RO (focal), CD5 (focal), CD10, CD23, bcl-6, CD138, p53, and Ki-67 (labeling = 27%). The immunoblastic cells were positive for CD30. The lymphoid cells were negative for Epstein–Barr virus (EBV)-related molecules of EBV latent membrane protein-1 (LMP-1) and EBV early RNAs (EBER). They were also negative for cytokeratins AE 1/3 and CAM5.2, cyclin D1, CD34, GFAP, α-smooth muscle actin, and S100 protein. Because of the heterogeneity of tumor cells and positive AL amyloid deposition, the author diagnosed it as primary MALT lymphoma. The patient is now free from tumors. Differential diagnosis was discussed.

Epithelioid sarcoma (ES) usually occurs in extremities. ES shows characteristic granulomatous morphologies, and its prognosis is not so poor. Proximal-type ES (PT-ES) is a variant of ES, and is characterized by central locations, severe atypical features, and poor prognosis. Both ES and PT-ES histologically show epithelial and sarcomatous patterns, and immunohistochemically express both vimentin and cytokeratins. A 77-year-old man presented with sore throat. The laryngoscope revealed a large polypoid tumor (4 × 3 × 4 cm) in upper pharynx, and a large biopsy was taken. The biopsy showed malignant epithelioid and spindle tumor cells. There were no apparent transitions between normal epithelial cells and tumor cells. The tumor consisted of malignant epithelioid and spindle cells with marked anaplasia. The tumor showed marked infiltrative features and lymphovascular permiations. Mitotic figures, atypical mitosis, and necrotic areas were present. No apparent features of sarcomas were seen. No rhabdoid cells were seen. Immunohistochemically, the malignant cells were positive for vimentin (3+, diffuse), CK AE1/3 (1+, focal), CK CAM5.2 (1+, diffuse), CK8 (1+, focal), CK18 (1+, focal), CD20 (1+, focal), p53 (3+, 84%), Ki-67 (labeling = 94%), CD68 (2+, only focal), and anti-trypsin (2+, only focal). They were negative for CK34BE12, CK5, CK6, CK7, CK14, CK19, CD99, CEA, CA19-9, CA125, EMA, S100 protein, NCAM, NSE, synaptophysin, chromogranin, α-smooth muscle actin, smooth muscle actin, desmin, CD34, CD31, CD45, D2-40, factor-VIII-related antigen, HMB-45, Melan-A, myoglobin, MDM2, CDK4, KIT, and PDGFRA. The author diagnosed this pharyngeal tumor as PT-ES, but the author cannot completely exclude the possibility of sarcomatoid carcinoma. The prognosis of patient was poor; the patient died of carcinomatosis 2 years after the manifestation.

Primary mucinous adenocarcinoma (MA) of vermiform appendix is extremely rare; only three cases have been reported in the English literature. A 77-year-old man presented with abdominal pain, and was diagnosed with acute appendicitis. Appendectomy was performed. The resected appendix showed submucosal swelling measuring 0.7×0.6×0.6 cm in the tip of appendix. The appendix showed inflammation and numerous diverticuloses. Microscopically, the submucosal swelling was a mucin lake in which adenocarcinoma cells were floating. The adenocarcinoma cells were MA in 80% and signet-ring cell carcinoma in 20%. The carcinoma cells were located in the submucosa, muscular layer and subserosa, sparing the mucosa. No apparent lymphovascular permeation was seen. The surgical margins were negative for tumor cells. The non-tumorous appendix shows numerous diverticulosis, diverticulitis, and appendicitis. Immunohistochemically, the tumor cells were positive for CK CAM5.2, CK AE1/3, CK8, CK18, CK19, CK20, EMA, CEA, CA19-9, MUC1, MUC2, MUC5AC, MUC6, NCAM, p53 and Ki-67 (labeling index = 23%). The tumor cells were negative for CK34BE12, CD5, CK6, CK7, NSE, chromogranin, synaptophysin, CA125, KIT, and PDGFRA. No metastasis has been seen 2.5 years after the operation.

The nested variant of urothelial carcinoma (NVUC) of urinary bladder (UB) is very rare and is characterized by the presence of benign-appearing urothelial carcinoma cells in lamina propria, sparing surface urothelial involvement. It shows aggressive clinical course despite the benign-looking histology. A 72-year-old woman presented with dysuria. Cystscopy revealed papillary infiltrative tumor, and transurethral resection of UB tumor (TUR-BT) was performed. It was composed of small three fragments, two of which showed urothelial carcinoma (UC) of low grade (G1) atypia. In one section, NVUC was seen. The nested areas showed small clusters of UC of mild atypia. They were remote from surface urothelium. The tumor was mildly invasive, and the pathological stage was pT1. Immunohistochemically, tumor cells were positive for various types of cytokeratins, EMA, p63, p53, MUC1, NSE, KIT, PDGFRA, Ki-67 (43%), NCAM and synaptophysin. This is the first case of NVUC of UV with neuroendocrine features and expressions of KIT and PDGFRA.

Primary lymphoma of soft tissue is very rare. An 80-year-old man presented with a right buttock tumor measuring 5 × 5 × 4 cm. Tumorectomy was performed. The tumor was located in the fascia and subcutaneous tissue, and encapsulated by a thin capsule. Histologically, the tumor showed atypical lymphoid cell proliferation. Immunohistochemically, the tumor cells were positive for CD45, CD20, CD79a, and CD138. The Ki-67 labeling was 90%. In contrast, they were negative for pancytokeratins, epithelial membrane antigen, CD10, MUM1, bcl-6, cyclin D1, CD3, CD30, CD45RO, TdT, CD56, S100 protein, HMB45, chromogranin, α-smooth muscle actin, and desmin. A diagnosis of diffuse large B-cell lymphoma (DLBCL) of soft tissue was made. The subtype of DLBCL is non-germinal center type (non-GC). Systemic investigation using various imaging modalities including CT, MRI and Ga-scintigraphy revealed small nodular lesions up to 1 mm in the lungs and liver. However, biopsies of these locations were not performed because of his old age. The nodular lesions of the liver and lungs were small in diameter (up to 1 cm), and it is strongly likely that the buttock tumor is primary. The patient was treated by R-CHOP chemotherapy and radiation. He was referred to another specialized hospital for his will.

Primary lymphoma of soft tissue is very rare. A 59-year-old Japanese man presented left leg tumor measuring 3 × 3 × 2 cm without skin ulceration. A large incisional biopsy was performed. It showed atypical lymphoid cell proliferation in subcutaneous tissue next to the fascia. Immunohistochemically, the tumor cells were positive for CD45, CD20, CD79α, λ-chain, and p53 protein. The Ki-67 labeling was 100%. In contrast, they were negative for various types of cytokeratins, epithelial membrane antigen, CD3, CD30, CD10, CD45RO, TdT, κ-chain, CD56, bcl-2, bcl-6 and MUM1. A diagnosis of diffuse large B-cell lymphoma (DLBCL) of non-germinal center type (DLBCL-non-GC) of soft tissue was performed. Systemic investigation using various imaging modalities including CT, MRI and Ga-scintigraphy revealed lymph nodes swelling in the inguinal region. The patient was treated by R-CHOP chemotherapy and radiation. The tumor and lymph nodes were markedly reduced in size. He is now alive with disease two years after the first manifestation.

Mixed tumor of soft tissue is extremely rare; only 15 cases have been reported in English literature. A 56-year-old man presented with a tumor in right arm. Physical examination showed a tumor measuring 3 × 3 × 3 cm of deep portion of right arm. MRI showed a well-defined deep tumor measuring 3 × 3 × 4 cm of arm next to fascia. The tumor was resected, and it was found that the tumor is located in deep subcutaneous tissue outside the fascia. Histologically, the tumor was well-defined and contained a fibrous capsule. The tumor cells showed no significant nuclear atypia. The tumor was composed of epithelial, myoepithelial, and stromal elements. The epithelial element formed tubules, and myoepithelial element showed solid nests and periepithelial linings. The epithelial element showed frequent apocrine features including apocrine snouts. The stromal element was composed of cartilage and myxoid tissues. Immunohistochemically, the epithelial element was positive for cytokeratin (CK) AE1/3, CK CAM5.2, CK34BE12, CK7, CK8, CK18, CK19, EMA, CEA, CD56, p53, and Ki-67 (labeling = 80%), but negative for CK5/6, CK14, CK20, vimentin, p63, S100 protein, CD10, CD34, ASMA, CD68, myoglobin, bcl-2, BMP-2, TGF-β1, CDK-4, and MDM2. The myoepithelial element was positive for CK AE1/3, CK CAM5.2, CK34BE12, CK5/6, CK7, CK8, CK14, CK18, p63, vimentin, CD10, S100 protein, bcl-2, p53, and Ki-67 (labeling = 20%), but negative for CK19, CK20, EMA, CEA, CD34, ASMA, CD68, CD56, myoglobin, BMP-2, TGF-β1, CDK-4 and MDM2. The stromal element was positive for vimentin, S100 protein (cartilage), and Ki-67 (labeling = 6%), but negative for other antigens examined including bcl-2, BMP-2, TGF-β1, CDK-4 and MDM2. No findings of metastasis, invasion, and recurrence were recognized clinically. The author speculates that the current mixed tumor was derived from misplaced apocrine glands in the deep soft tissue.

Basaloid squamous cell carcinoma of esophagus (BSCC-E) is rare. This case report is the first demonstrating KIT protein expression of BSCC-E. A 74-year-old man presented with dysphagia. Endoscopy revealed a polypoid tumor (2 × 2 × 2.5 cm) with a stalk in cervical esophagus. Biopsy showed squamous cell carcinoma with undifferentiated areas. An endoscopic submucosal dissection (ESD) was performed. Grossly, it was solid tumor with white cut surface. Histologically, the tumor was hypercellular carcinoma consisting of solid areas of island. The tumor cells were composed of basaloid malignant cells with hyperchromatic nuclei, scant cytoplasm, and basophilic cytoplasm. Many mitotic figures were recognized. Foci of comedonecrosis were scattered. Areas of squamous and glandular differentiations were scattered. Immunohistochemically, the tumor cells were positive for pancytokeratin (PCK) CAM5.2, PCK AE1/3, cytokeratin (CK) 7, KIT, CEA, CA19-9, EMA, Ki-67 (labeling index = 80%). The tumor cells were negative for CK20, PDGFRA, NSE, vimentin, estrogen receptor, p53 protein, chromogranin, synaptophysin, CD56, and TTF-1.

Primary signet-ring cell carcinoma (SRCC) of vermiform appendix is extremely rare; only three cases have been reported in the English literature. An 89-year-old man suddenly presented right lower abdominal pain, and transferred to a hospital, where he was diagnosed with acute appendicitis by physical data, blood data, and CT. He was further transferred to our hospital for emergency operation. Physical examination showed positive abdominal pain, Blunberg sign, and Rosenstein sign. Blood test showed leukocytosis and increased C-reactive protein. An appendectomy was performed. Gross examination during operation showed inflamed appendix, appendiceal adhesion, and acute peritonitis. Gross pathological examination showed no apparent tumor, but the proximal appendix showed wall thickening and luminal occlusion. The appendix was cut into three sections, and was observed under microscopically. Nests of carcinoma cells were seen in the proximal appendix. The carcinoma was composed of SRCC (70%) and mucinous carcinoma (30%). The size of carcinoma was 6 × 7 mm. The carcinoma cells invaded into muscular layer. No lymphovascular permeation was seen. The cut margins were negative for carcinoma cells. Immunohistochemically, SRCC cells were positive for cytokeratin (CK) AE1/3, CK CAM5.2, CK8, CK18, CK19, CK20, EMA, CEA, CA19-9, p53, Ki-67 (labeling = 30%), CDX2, MUC2, and MUC5AC. They were negative for CK34PE1, CK5/6, CK7, CK14, p63, vimentin, TTF-1, MUC1, MUC 5AC, NSE, synaptophysin, chromogranin, and CD56. No further treatments were performed, because the appendiceal carcinoma was small, the surgical margins were negative and the patient was very old. He was followed up by various imaging modalities. No recurrence or metastasis is found 17 months after the operation.

Extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) occurring in inflammatory bowel diseases, including ulcerative colitis (UC) and Crohn′s disease, has been reported, although it is extremely rare. An 18-year-old man with a two-years history of UC underwent colon endoscopy, and was found to have active total UC ranging from anus to cecum. Six biopsies were obtained. The microscopic examinations showed severe infiltrations of atypical small lymphocytes. They showed hyperchromatic nuclei and increased nucleocytoplasmic ratio and scattered immunoblastic cells. Centrocyte-like atypical lymphocytes, monocytoid cells, and plasma cells were seen in some places. Vague germinal centers were present, and apparent lymphoepithelial lesions were seen. No crypt abscesses were seen, and there were few neutrophils. No apparent other findings of UC were seen. Immunohistochemically, the atypical lymphocytes were positive for vimentin, CD45, CD20, CD79α, CD138, κ-chain, λ-chain, and p53 and Ki-67 antigen (labeling index = 63%). They were also positive for CD45RO, CD3, and CD15, but these positive cells were very scant compared with CD20 and CD79α. They were negative for CD10, CD30, CD56, cytokeratin (CK) AE1/3, CK CAM5.2, CK34BE12, CK5, CK6, CK7, CK8, CK14, CK18, CK19, CK20, EMA, chromogranin, synaptophysin, NSE, S100 protein, CEA, CA19-9, p63, and HMB45. Without clinical information, the appearances are those of MALT lymphoma. However, with clinical information, making the diagnosis of MALT lymphoma was hesitated. It is only mentioned herein that atypical lymphocytic infiltrations indistinguishable from MALT lymphoma occurred in an 18-year-old male patient with a two-year history of UC.

Prostatic carcinoma initially manifesting as only cervical lymph node swelling is a rare phenomenon. A 74-year-old man presented left cervical lymphadenopathy. An excisional biopsy was performed, and it was pathologically diagnosed as metastatic thyroid follicular carcinoma. However, imaging technique revealed no thyroid tumor or tumor in the body. The lymph node was re-examined 23 months after the first diagnosis: it showed adenocarcinoma positive for PSA and PSAH. Biopsy of the prostate was performed immediately, and it showed Gleason 8 (4 + 4) prostatic adenocarcinoma. Imaging technique showed two small metastases to pelvic bone. No other metastatic lesions were detected. The patient later developed acute myelogenous leukemia, and died of respiratory failure. The present case shows that prostatic adenocarcinoma can present only cervical lymph node swelling without metastases to other organs.

The author reports a very rare case of spindle cell carcinoma of the common bile duct with an emphasis on immunohistochemical features. A 65-year-old man was admitted to our hospital because of jaundice. Imaging modalities revealed a tumor of the common bile duct, and bile cytology demonstrated malignant cells. A pancreatico-duodenectomy was performed. Grossly, an elevated tumor (15 × 10 × 3 mm) was present in the middle portion of the common bile duct. Microscopically, the tumor consisted of well-differentiated adenocarcinoma (20% in area) and spindle cell carcinoma (80% in area). There were gradual transitions between the two. The tumor cells invaded into the serosa. Immunohistochemically, the spindle cell carcinoma element was positive for four types of pancytokeratins, cytokeratin 7 (CK7), CK8, CK18, CK19, CK20, epithelial membrane antigen, vimentin, p53 protein, Ki-67 (labeling = 52%), and CEA. It was negative for high-molecular-weight CK, CK5/6, CK14, p63, neuron-specific enolase chromogranin, synaptophysin, CD56, CA19-9, CD34, desmin, S100 protein, myoglobin, α-smooth muscle antigen, CD34, CD68 and KIT. The adenocarcinoma element showed similar immunoreactivity except for negative vimentin, and positive CA19-9. The present case is the first report of spindle cell carcinoma of the common bile duct demonstrating an extensive immunohistochemistry. The spindle cell carcinoma in the present case may be derived from sarcomatous transformation of the adenocarcinoma element. CK20 newly emerges in the development of spindle cell carcinoma of the common bile duct.

Adenosquamous carcinoma (ASC) and pure squamous cell carcinoma (SCC) of the pancreas are very rare diseases. The author herein reports two cases of ASC and SCC of the pancreas. The first case is ASC. An 80-year-old woman was admitted to our hospital because of abdominal pain and weakness. Imaging modalities including CT, MRI and ERCP revealed a pancreatic body tumor. Distal partial resection of the pancreas and splenectomy were performed. Grossly, an infiltrative solid tumor measuring 3 × 4 × 4 cm was present in the pancreatic body. Histologically, it was an ASC consisting of poorly differentiated adenocarcinoma element (20% in area) and SCC element (80%). There was a gradual transition between the two. Many perineural invasions and lymphovascular permeations were recognized. The patient died of systemic metastasis five months after operation. The second case is an SCC. A 69-year-old woman presented with abdominal pain and jaundice. Imaging modalities including CT, MRI and ERCP revealed a tumor in the head of the pancreas. Pancreaticoduodenectomy was performed. Grossly, an infiltrative solid tumor measuring 5 × 5 × 6 cm was present. Histologically, the tumor was pure SCC. The SCC was moderately differentiated SCC. A large number of perineural invasions and lymphovascular permeations were present. The patient died of systemic metastasis three months after operation. The author speculates that ASC of the pancreas may be derived from squamous tansdifferentiation of adenocarcinoma element or from pluripotent stem cells, and that SCC of the pancreas may arise from malignant transformation of squamous metaplasia of pancreatic ducts or from pluripotent stem cells.

Heterotopic pancreatic tissue of the stomach is a rare condition. The author herein reports three cases of heterotopic pancreatic of the stomach. The three cases were found in the 8,154 gastric specimens (biopsy 6,122 cases, gastrectomy 2,032 cases) of our pathology laboratory; the frequency was 0.04%. The first case was a 57-year-old woman who presented with epigastralgia. Endoscopic examination revealed a submucosal tumor in the body of the stomach. Partial gastrectomy was performed. Histologically, the lesion measured 25 × 20 × 25 mm and was submucosal heterotopic pancreatic tissue with hemorrhage and cystic changes. It was composed of acinar cells, ducts, and islets (Heinrich type I). The second case was a 57-year-old man without symptoms. Endoscopic examination revealed a submucosal tumor, and biopsy was taken. The biopsy showed heterotopic pancreatic tissue in the mucosa. It consisted of acinar cells and ducts (Heinrich type II). The third case was a 54-year-old woman without symptoms. Endoscopic examination showed chronic gastritis, and biopsy was obtained. The biopsy revealed heterotopic pancreatic tissue in the mucosa. It consisted of acinar cells and ducts (Heinrich type II). The first case appears to be a true heterotopic pancreas of congenital abnormality. The second and third cases seem to be heterotopic pancreatic tissues of congenital anomaly of the gastric mucosa. The histogenesis of heterotopic pancreatic tissue is discussed.

Background: Metastatic carcinoma manifesting as a mass in external auditory canal (EAC) is very rare, and prostatic adenocarcinoma (PA) presenting firstly as a mass of EAC has not been reported. Aim: To report a case of PA manifesting as only a mass of EAC. Case report: A 77-year-old man presented a right EAC mass. Otoscope identified a small mass approximately 7 mm in right EAC neat to the external orifice. Biopsy showed well differentiated adenocarcinoma with cribriform appearances. The author highly suspected metastatic prostatic PA (Gleason 4 + 4 = 8) and performed an immunohistochemical (IHC) study. The IHC showed positive prostate-specific antigen, prostatic acid phosphatase, alpha-methylacyl-CoA racemase, cytokeratin (CK) 7, and CK20. The tumor was negative for TTF-1, CDK2, and NCAM. The definite diagnosis of PA metastatic to EAC was made. The patient was referred to Urology and prostatic needle biopsy showed PA with immune-expressions of PSA, PAP, and AMACR. Serum PSA was high (63 ng/L). Imaging techniques showed a few metastases in bones of vertebula and ribs. The skull appeared free of metastasis, and head and neck soft tissue showed no metastatic areas except for the shadow of EAC. The patient is now treated with hormone and chemotherapy. Conclusion: The first case of an EAC mass that is a metastatic lesion of prostatic adenocarcinoma, was reported.

Appendiceal diverticulosis is a rare condition. Herein reported is a case of appendiceal diverticulosis and diverticulitis clinically masquerading as appendiceal carcinoma. A 62-year-old woman presented with abdominal pain. US and CT showed a tumor measuring 5 × 4 × 4 cm in vermiform appendix. Colon endoscopy showed mucosal elevation and irregularity in the orifice of vermiform appendix. A biopsy of the appendiceal mucosa showed no significant changes. Clinical diagnosis was appendiceal carcinoma and wide excision of terminal ileum, appendix, cecum, and ascending colon was performed. Grossly, the appendix showed a tumor measuring 5 × 3 × 4 cm. The appendiceal lumen was opened, and the appendiceal mucosa was elevated and irregular. The periappendiceal tissue showed thickening. Microscopically, the lesion was multiple appendiceal diverticula. The diverticula were penetrating the muscle layer. The mucosa showed erosions in places. Much fibrosis, abscess formations, and lymphocytic infiltration were seen in the subserosa. Abscesses were also seen in the diverticular lumens. Some diverticula penetrated into the subserosa. The pathologic diagnosis was appendiceal diverticulitis. When they encounter an appendiceal mass, clinicians should consider appendiceal diverticulitis as a differential diagnosis.

Herein reported is a case of inflammatory pseudotumor (IPT) of kidney. It is not described in WHO, AFIP, and other books. A review of the literature revealed about 35 cases. A 76-year-old man underwent nephrectomy under clinical diagnosis of renal pelvic carcinoma. Grossly, a solid tumor was seen in renal parenchyma. Microscopically, it was composed of spindle cell tissue with inflammation and many necrotizing granulomas. Epithelioid histiocytes were abundant but giant cells were few. Lymphocytes and plasma cells were also seen. The features suggested tuberculosis (TB), but Ziehl-Neelsen stains and PCR revealed no TB bacillus. Immunohistochemistry showed that the tumor spindle cells were positive for vimentin, CD68, CD45, and Ki-67 (labeling = 18%), α-smooth muscle antigen, and NSE. Focal staining of KIT (mast cells), S100 protein (Langerhans cells), and CD10 (spindle cells) was present. IgG4 was negative. The tumor spindle cells were negative for other antigens examined.

Myopericytoma (MPC) of the oral cavity is extremely rare. Herein reported is a case of MPC of low grade malignancy in the oral cavity. A 61-year-old man noticed a tumor of the cheek mucosa, and admitted to our hospital. Oral examination revealed a reddish elevated tumor of the cheek mucosa. Tumorectomy with wide margins was performed. The clinical diagnosis was pyogenic granuloma. Grossly, the tumor was reddish, and measured 1 x 1 x 1cm. Microscopically, oval to spindle tumor cells with hyperchromatic vesicular nuclei and many vasculatures were seen. The tumor cells were contiguous and mixed with endothelial cells in many blood vessels, thus resembling pericytes. Mitotic figures were scattered. The surgical margins were negative for tumor cells. Immunohistochemically, the tumor cells were positive for vimentin, α-smooth muscle actin and p53. The Ki67 labeling was 40%. The tumor cells were negative for cytokeratins (AE1/3 and CAM5.2), CD31, CD34, S100 protein, HMB45, CD10, vimentin, desmin, and factor VIII-related antigen. The endothelium of the vessels were positive for vimentin, CD31, CD34 and factor VIII-related antigen, but negative for α-smooth muscle actin, p53, cytokeratins (AE1/3 and CAM5.2), S100 protein, HMB45, CD10, vimentin, and desmin. The Ki67 labeling was 5%. Because the pericytoid tumor cells showed α-smooth muscle actin and negative for endothelial markers, MPC was diagnosed. In addition, because there was some atypia and mitotic figures were scatters and also because the tumor cells were positive for p53 and Ki67 labeling was high, a pathological diagnosis of MPC with low grade malignancy was made. No recurrence was observed, and the patient is now free from tumor 6 months after the operation.

Although many clinicopathological studies malignant melanoma of the conjunctiva have been reported, there are no studies of the expression and gene mutation of KIT and PDGFRA in melanoma of the conjunctiva. A 69-year-old Japanese woman consulted to our hospital because of black mass (0.7 x 0.7 x 0.6 cm) in the conjunctive. A biopsy was taken. The biopsy showed malignant epithelioid cells with melanin deposition. Immunohistochemically, the tumor was positive for S100 protein, HMB45, p53, Ki-67 (labeling=30%), KIT and PDGFRA. The tumor was negative for cytokeratins (AE1/3 and CAM5.2). A genetic analysis using PCR-direct sequencing revealed no mutation of KIT gene (exons 9, 11, 13, and 17) and the PDGFRA gene (exons 12 and 18). The pathological diagnosis was conjunctival melanoma. Despite chemotherapy, the patient developed multiple metastases of melanoma, and died of melanoma 7 years after the biopsy. In conclusion, the author reported a case of melanoma of conjunctive expressing KIT and PDGFRA without gene mutations of KIT and PDGFRA.

The nested variant of urothelial carcinoma (NVUC) is characterized by the presence of benign-appearing urothelial carcinoma cells in the lamina propria, sparing the surface urothelial involvement. NVUC shows aggressive clinical course despite of benign-looking histology. Herein reported are two cases of NVUC. One is 80-year-old woman, and another is 78-year-old man. In both cases, atypical cells forming nests and tubules were seen in the lamina propria without surface urothelial involvement. One case resembled nephrogenic metaplasia and another proliferated Brunn’s nest or inverted papilloma. Immuno - histochemically, both cases showed positive p53 and high Ki67 labeling, suggesting that both cases are malignant. Immuno histo - chemically, one case was characterized by positive cytokeratins, EMA, p53, Ki-67 (labeling= 15%), α-methylacyl CoA racemase, CA19- 9, and MUC1, and another case by positive cytokeratins, EMA, p63, p53, Ki-67 (lebeling= 30%), CD10, CEA, and MUC1. Cyto keratin immunoprofiles were described and other antigens’ expressions were shown. The patients are now free of tumor 6 and 15 months after the resection of the bladder tumor.

Cytokeratins (CK) are good markers of epithelial tumors, and most of carcinomas including small cell lung carcinoma (SCLC) expresses CK. Herein reported is a case of SCLC without CK expression.

Although several clinicopathological studies of malignant melanoma of the nasal cavity have been reported, there are no studies of the expression and gene mutation of KIT and platelet derived growth factor receptor-α (PDGFRA) in melanoma of the nasal cavity. A 92-year-old Japanese woman consulted to our hospital because of right nasal obstruction and epistaxis. Physical examination and imaging modalities showed a tumor of the right nasal cavity. A biopsy was taken, and it showed malignant epithelioid cells with melanin deposition. Immunohistochemically, the tumor was positive for S100 protein, HMB45, p53, Ki-67 (labeling=20%), KIT and PDGFRA. The tumor was negative for cytokeratins (AE1/3 and CAM5.2). A genetic analysis using PCR-direct sequencing revealed no mutation of KIT gene (exons 9, 11, 13, and 17) or the PDGFRA gene (exons 12 and 18). The pathological diagnosis was primary malignant melanoma of the nasal cavity. The tumor was reduced in size by local resection and chemotherapy (Darthmose regimen: dacarbazine, carmustine, cisplatine, and tamoxifen), and the patient is now alive and free from metastasis 9 months after the first manifestation. In conclusion, the author reported a case of melanoma of the nasal cavity expressing KIT and PDGFRA without gene mutations of KIT and PDGFRA.