title: [Neuroendocrine carcinoma of the skin. Morphology and differential diagnosis based on 2 clinical cases].
abstract: Two cases of neuroendocrine carcinomas of the skin were examined by light microscopic and electron microscopic methods. In both patients the disease showed an unusual course characterized by the occurrence of numerous and wide-spread skin nodules. Light microscopically, we found a uniform tumor tissue with trabecular, nest- or cord-like arrangement of cancer cells. At electron microscopic investigation, neurosecretory granules (dense-cored vesicles) were detected. These organelles had a diameter between 90 and 220 nm. Furthermore, small bundles of intermediate filaments and a well-developed Golgi system as well as numerous vesicular structures were recognized. Specialized cell junctions were lacking, tumor cell complexes were often enveloped by a basal lamina-like structure. The light microscopic and electron microscopic observations are in accordance with other reports. The relationship of neuroendocrine skin carcinomas to Merkel cells is discussed. However, we suggest an origin of these carcinomas from multipotent epithelial stem cells. The multicentric development in our cases, the tumor localization, and recent electron microscopic findings in basal cell carcinomas lend the basis for speculations on relations between neuroendocrine carcinomas and basal cell carcinomas of the skin. Lastly, the morphologic differential diagnosis of neuroendocrine carcinomas is presented. Special attention is called to the distinction from melanomas, lymphomas and other neuroendocrine tumors. In spite of the fact that neuroendocrine carcinomas of the skin are well defined and considered to be a clinico-pathologic entity there are some open questions concerning the tumor biology and histogenesis.
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis / Q000473:pathology* / Q000648:ultrastructure; D000368:Aged; D002280:Basal Cell Carcinoma / Q000175:diagnosis; D003594:Cytoplasmic Granules / Q000648:ultrastructure; D003937:Diagnosis, Differential; D006801:Humans; D008297:Male; D008854:Microscopy, Electron; D008875:Middle Aged; D012867:Skin / Q000473:pathology / Q000648:ultrastructure; D012878:Skin Neoplasms / Q000175:diagnosis / Q000473:pathology* / Q000648:ultrastructure
vernacular_title: Das neuroendokrine Karzinom der Haut. Morphologie und Differentialdiagnose an Hand zweier eigener Beobachtungen.