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We describe an insulinoma of the pancreas in a 56-year-old patient, which showed insular-ductular differentiation in its liver metastasis. Although the primary tumor was uniformly endocrine in nature with insulin production, the metastasis contained two distinct cell types in organoid arrangement. One cell type was insulin-positive and was arranged in islet-like structures; the other was insulin-negative but distinctly pan-cytokeratin and cytokeratin 7 positive and arranged in ducts. In the primary tumor and the metastasis, the tumor cells were surrounded by a desmoplastic stroma. As to the histogenesis of the tumor and its metastasis, we discuss the following possibilities: (1) the tumor cells might derive from a common stem cell that matures into two phenotypically different cell lines, resembling the situation in embryogenesis and (2) one tumor cell type originates from the other by transdifferentiation (metaplasia). We conclude that the parallel occurrence of endocrine and ductal differentiation supports the concept that, under certain conditions, islet cells and ductular cells may also originate from islets and that mixed endocrine/exocrine pancreatic tumors do not necessarily arise from totipotent duct cells but might also have a primary endocrine cell origin.

The incidence of gastrointestinal stromal tumors (GISTs) in children is exceptionally low. However, during the last decade these tumors attracted increasing attention, because they were found to express the cell surface transmembrane receptor kit (CD117) that has tyrosine kinase activity. This tyrosine kinase can be semi-selectively inhibited by signal transduction inhibitors such as imatinib mesylate (Glivec), which is a competitive inhibitor of c-kit, c-abl, platelet-derived growth factor receptor-alpha (PDGFR-alpha) and PDGFR-beta, and abl-related gene (arg). The authors present the clinical, radiographic, and pathological findings of 4 children who were diagnosed with gastric GIST. One of them had an incomplete Carney triad including GIST and mediastinal paraganglioma. All 4 patients presented with anemia and anemia-related symptoms and underwent total resection of the tumor. One patient received additional chemotherapy (in the pre-imatinib era) and 2 patients received a short course of imatinib mesylate. With a follow-up of 116, 55, 23, and 10 months all patients are alive in first complete continuous remission. In children and adolescents, particularly in female patients, GISTs should be included in the differential diagnosis of anemia secondary to gastrointestinal hemorrhage. Complete surgical resection is the mainstay of treatment for this tumor, with imatinib mesylate restricted to patients with advanced or metastatic tumors. Since late recurrences (up to 30 years following initial diagnosis) are reported, a life-long follow-up is mandatory in these patients.

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Background. Angiotropic large cell lymphoma is a rare lymphoproliferative disorder that affects vessels of almost all organs. Therefore, many different signs and symptoms can be observed and may delay a rapid diagnosis in these patients. However, no association between angiotropic large‐cell lymphoma and thrombotic microangiopathy (TMA) has been reported so far. Methods. The case report describes a 69‐year‐old female Caucasian who presented with fever, neurologic symptoms, microangiopathic hemolytic anemia, thrombocytopenia, and hyaline thrombi within small vessels. TMA was diagnosed and intense treatment, including plasma exchange and corticosteroid therapy, was initiated. Nevertheless, the patient died 3 days after admission. A postmortem examination including immunohistochemistry and molecular studies was performed. Results. Autopsy revealed angiotropic large cell lymphoma with tumor cell aggregates in small vessels of the brain, myocardium, lungs, liver, small and large intestines, mesenterium, kidneys, and lymph nodes. Immunohistochemical analysis of the tumor cells showed positive reactions with B‐cell markers, but negative T‐cell and epithelial cell markers. Molecular studies using polymerase chain reaction with primers for the rearranged immunoglobulin heavy chain and the T‐cell receptor beta chain gene confirmed the diagnosis of a monoclonal B‐cell disorder. Conclusion. TMA can occur in association with angiotropic large cell lymphoma and, furthermore, can be its sole clinical manifestation. Cancer 1995;75:1167–70.