Masaki Ohmori

Loss of heterozygosity in actinic keratosis, squamous cell carcinoma and sun-exposed normal-appearing skin in Japanese: difference between Japanese and Caucasians

Actinic keratosis (AK) has been considered to be a precursor of squamous cell carcinoma (SCC). However, based on epidemiological and molecular studies, it has become questionable to regard AK as a precancerous lesion. We analyzed 37 AKs and 14 sporadic SCCs using six microsatellite markers in order to elucidate if any genetic instability or loss of heterozygosity (LOH) was implicated in tumorigenesis and progression of non-melanocytic skin tumor. Microsatellite instability (MSI) was not found in any of the AKs or SCCs indicating that genetic instability has little implication in the tumorigenesis of sporadic non-melanocytic skin tumor. LOH was found in seven of 37 lesions of AK, but in only one of 14 lesions of SCC. The significantly lower frequency of LOH than that previously reported in Caucasians suggested that the molecular pathogenesis of AKs and SCCs might be different between Japanese and Caucasians. The higher frequency of LOH in AKs than in SCCs in the present study supported the previous epidemiological and molecular studies that AK was not likely to proceed to SCC. LOH was also demonstrated in histologically normal-appearing skin in three cases suggesting that genetic alteration occurs before histological change appears in the sun-exposed skin.

Combined analysis of flow cytometry and morphometry of ovarian granulosa cell tumor

Background. It is difficult to determine the prognosis of granulosa cell tumors (GCT) at the time of diagnosis.

Detection of c-Ki-ras point mutation from pancreatic juice. A useful diagnostic approach for pancreatic carcinoma

SummaryCytological diagnosis of pancreatic carcinoma sometimes poses difficulties in distinguishing malignant from benign cells. Recent molecular study of pancreatic carcinoma has revealed a very high incidence of a point mutation of the c-Ki-ras oncogene at codon 12 in this neoplasm. To take advantage of this technique for the diagnosis of pancreatic carcinoma, we attempted to amplify the c-Ki-ras gene from endoscopically obtained pancreatic juice by isolation of DNA and polymerase chain reaction (PCR) coupled with restriction fragment length polymorphism (RFLP). PCR was possible in approx 70% of the cases. A point mutation was nonradioisotopically detected in 4 of 6 pancreatic carcinomas and in one intraductal papillary neoplasm, whereas no mutation was detected in other cases. Thus, this method was thought to be useful for the diagnosis of pancreatic carcinoma.

Collision tumor of cutaneous malignant melanoma and basal cell carcinoma.

An extremely rare case of a collision tumor of malignant melanoma (MM) and basal cell carcinoma (BCC) located in the temporal scalp of a 78-year-old male is reported. Microscopic examination revealed a collision tumor consisting of the nodular type, Clarks level IV MM, and a pigmented BCC. The tumor was studied by immunohistochemistry and was analyzed for point mutations of codons 12 and 61 of H-ras, K-ras and N-ras oncogenes. Tumor cells of the MM were positive for S-100 protein, HMB-45 and vimentin, but negative in the BCC. The malignant melanoma possessed an activating A to T transversion in codon 61 of N-ras gene, which is the code for leusine instead of glutamine. This is the first report of ras oncogene mutation in such a collision tumor. MM and BCC are clearly different in terms of histological, immunohistochemical and ras gene mutation analyses. These findings support the view that the association of MM and BCC in this collision tumor is a chance occurrence.

Lipofibromatous hamartoma of nerve in the foot.

A case of lipofibromatous hamartoma in the foot is described. This tumor‐like lesion commonly occurs in the hands, wrists and forearms of young persons. The median nerve is affected in the great majority of cases. Only very rarely, however, is it found in the nerves of the foot. It is believed that the present study is the seventh reported case of lipofibromatous hamartoma in the foot, and is the first case reported in Japan. A review shall be made of the six reported cases in the foot.

Myospherulosis in Japan. A report of two cases and an immunohistochemical investigation

We report two cases of myospherulosis and offer review of the Japanese literature. Case 1 was a 41-year-old woman with cystic tumors under the fascia of the right major gluteal muscle. Case 2 was a 36-year-old man with subcutaneous cystic tumors in the right buttock. The characteristic saccular structures enclosing numerous small spherules were observed in the cysts. These spherules measured 5–7 μm in diameter and stained with Masson trichrome, Giemsa, Papanicolaou, and alizarin red S for hemoglobin. The myospherules also stained positively by the immunohistochemical method for hemoglobin. These findings support the contention that the spherules and parent bodies were derived from erythrocytes altered by foreign lipids or fat.

Intrathyroidal branchial cleft‐like cyst in chronic thyroiditis

An extremely rare case of intrathyroidal branchial cleft‐like cyst is reported. A 71‐year‐old man complained of a growing mass in the right lateral neck. A cystic mass in the upper lobe of the right thyroid was demonstrated by ultrasonography and computed tomography. The surgical specimen revealed a cystic mass with dense fibrous capsule, 22 × 20 × 10 mm in size. Microscopically, the cyst walls and the surrounding thyroid tissue contained severe lymphoid cell infiltration with lymphoid follicle. Squamous epithelium lined the cyst wall. Immunohistochemically, squamous epithelium was positive for keratin, cytokeratin 19, carcinoembryonic antigen, and epithelial membrane antigen, but negative for calcitonin and chromogranin A. The patient is currently well with no evidence or recurrence for 43 months.

Sarcomatoid hepatocellular carcinoma with chondroid variant: Case report with immunohistochemical findings

A case of sarcomatoid hepatocellular carcinoma (HCC) with a chondroid variant in a 72‐year‐old woman is reported. Histologically, the tumor consisted of typical HCC of adult type, with an adenocarcinoma‐like structure and a sarcomatoid component containing multinodular chondroid foci. Transition from carcinoma to sarcomatoid component was observed. The cells containing mucus were extremely few in adenocarcinoma‐like structures. Immunohistochemically, other than typical HCC, some of the chondroid cells, adenocarcinoma‐like cells and sarcomatoid cells were positive for alpha‐fetoprotein.

A case of infantile rhabdomyofibrosarcoma with immunohistochemical, electronmicroscopical, and genetic analyses

A case of infantile rhabdomyofibrosarcoma arising on the buttocks of a 15-month-old boy is reported with histological, immunohistochemical, electronmicroscopical, and cytogenetic findings. Histological examination showed a proliferation of spindle-shaped cells in a fasciculated pattern, with occasional rounded rhabdomyoblastic cells with abundant eosinophilic cytoplasm. Immunohistochemically, the tumor cells expressed desmin and MyoD1 but were only weakly positive for myoglobin. No clear rhabdomyoblastic features were observed by electronmicroscopic examination. Chromosome analysis showed a clone of 46, XY, der(2)t(2;11)(q37;q13), different from any karyotypic abnormality in the original report of this neoplasm. Loss of heterozygosity at 11p15.5, the most frequent genetic alteration in embryonal rhabdomyosarcoma, was not detected. The low degree of striated muscle differentiation and tumor localization supported the diagnosis of infantile rhabdomyofibrosarcoma rather than spindle-cell rhabdomyosarcoma in this case. The present case has been uneventful as of 25 months after surgery. The rather long recurrence-free period, which has not been reported in previous cases, may be attributable to chemotherapy-induced rhabdoid differentiation of the tumor cells.

Early stage gastric MALT lymphoma with high-grade component cured by Helicobacter pylori eradication.

Abstract: A 68-year-old woman was diagnosed with gastric lymphoma of the mucosa-associated lymphoid tissue (MALT) type with a high-grade component. Surgical treatment was recommended because of the presence of the high-grade component, but she refused surgery. As an alternative, she received Helicobacter pylori eradication treatment, which successfully induced regression of the lymphoma. She shows no sign of recurrence endoscopically and histologically, as of 29 months after the eradication treatment. Moreover, the B-cell monoclonality and Helicobacter pylori infection demonstrated at diagnosis has disappeared. This is one of the rare cases of gastric lymphoma of the MALT type with a high-grade component cured by Helicobacter pylori eradication alone.