Gastrointestinal stromal tumor (GIST) is currently considered to be derived from the interstitial cells of Cajal (ICC). To test the hypothesis that omental mesenchymal tumor is also a type of GIST, we evaluated the expression of specific molecules in GIST, and c-kit gene mutation in omental mesenchymal tumors, and we identified a possible counterpart of ICC in the omentum. Immunohistochemically, all of the omental mesenchymal tumors (n = 5) were positive for both KIT and CD34, and three of the five tumors were also positive for an embryonic form of smooth-muscle myosin heavy chain (SMemb). Polymerase chain reaction-single-strand conformational polymorphism analysis (PCR-SSCP) and direct sequencing revealed mutations in c-kit gene exon 11 in all five tumors. As for the ICC counterparts in the omentum, there were some KIT-positive mesenchymal cells resembling ICC at the surface of the omentum. Double fluorescence immunostaining, using anti-KIT polyclonal antibodies and monoclonal antibodies against other molecules, demonstrated that KIT-, CD34- and SMemb-positive cells were present just beneath the mesothelial cells of the omentum. These results show that omental mesenchymal tumor corresponds to GIST of the omentum, and that KIT-positive bipolar mesenchymal cells may be a counterpart of ICC in the gastrointestinal tract. Identification of a new type of KIT-positive mesenchymal cell in the omentum may lead to the discovery of a new physiological role for this organ.

Thyroid carcinoma is the first symptom in some patients with familial adenomatous polyposis (FAP). We evaluated the cellular localization of β β β β-catenin in thyroid carcinomas associated (n = = = =4)or not associated (n = Thyroid carcinoma occurs much more frequently in young female patients with familial adenomatous polyposis (FAP) than in matched controls.=1, 2) The relative risk for thyroid carcinoma in FAP women under 35 years of age is 160 times normal, and more importantly, 30% of thyroid carcinomas are diagnosed 4-12 years before the development of polyposis.2) Germline mutation of the adenomatous polyposis coli gene (APC) is responsible for the FAP. APC protein controls the nuclear accumulation of β-catenin, a transcriptional activator regulated by the Wnt signaling pathway, by a combination of nuclear export and cytoplasmic degradation.3, 4) The latter function of APC is lost by the mutation and/or deletion of APC in both alleles in the colon carcinomas of FAP patients, and this results in the nuclear accumulation of β-catenin.5) Then, it interacts with Tcf-4, the Lef/TCf transcription factor, leading to activation of several developmentally related genes, such as c-myc, and subsequent cell proliferation. To test the possibility that the abnormality of the APC/β-catenin pathway is also involved in FAP-associated thyroid carcinoma, we immunohistochemically evaluated β-catenin in FAP-associated thyroid carcinoma as well as sporadic thyroid carcinomas. If β-catenin-accumulation is specific to FAP in thyroid carcinomas, it can be a hallmark to identify occult FAP in young patients with thyroid carcinoma.Four FAP patients with thyroid carcinoma were enrolled in this study. Three were sisters and the other was a daughter of one of them. The thyroid carcinoma was the first symptom of the proband at age 16, five years before the diagnosis of FAP with a rectal carcinoma. Thyroid carcinomas were detected at the age of 12 in the case of her sister, and at 13 in her daughter. The clinical course of the sisters has been previously reported, and germline APC mutation was found at codon 848 (AAA to TAA, stop). 6) In the case of the fourth patient, who had no relation to the three patients described above, multiple colon carcinomas and multiple thyroid carcinomas were diagnosed simultaneously (Fig. 1A). The clinical course of this 26-year-old woman has also been reported previously.7) Germline APC mutation was detected at codon 175 (ACT to AT, C deletion), resulting in truncation at codon 184. A somatic mutation was also demonstrated at codon 886 (CAG to TAG, stop) in one of the thyroid carcinomas.As for the sporadic thyroid carcinomas, two series were evaluated: the first series was papillary thyroid carcinomas which had been consecutively resected at the Department of Surgery, Jichi Medical School (n=140, age 17-83 years old), including 11 cases younger than 30 years of age. The second series consisted of thyroid carcinomas of patients aged less than 30, treated at Tokyo Metropolitan Komagome Hospital. Twenty-seve...

We report a rare case of pseudomyxoma retroperitonei in a 58-year-old woman with a past history of severe appendicitis. The imaging showed a multicystic mass similar to pseudomyxoma peritonei, but the tumor was located in the retroperitoneal space.

This report describes a patient with intravascular large B-cell lymphoma (IVLBCL) with central nervous system involvement at the time of diagnosis who achieved complete remission for over 5 years in response to therapy. The patient, a 71 year-old woman, was previously healthy with the exception of taking verapamil for paroxysmal supraventricular tachycardia. She had presented with pyrexia and gradually progressive anemia. Brain magnetic resonance imaging revealed an infarct-like lesion in the pons, although no paralysis was observed. She was diagnosed with IVLBCL on the basis of random skin biopsy. After eight cycles of rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone therapy, abnormal laboratory data had normalized, and no pontine lesion was evident on magnetic resonance imaging without receiving any intrathecal chemotherapy. IVLBCL is associated with poor prognosis, particularly in patients with central nervous system involvement. Early initiation of rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone therapy and drug interactions between anticancer agents and verapamil as a p-glycoprotein inhibitor were considered the possible reasons for favorable outcome in the present case.

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