title: Primitive small cell tumor with epithelial, gangliocytic, neuroendocrine, and mesenchymal differentiation: report of 2 cases.
abstract: The authors describe 2 tumors that, to the best of their knowledge, are hitherto undescribed. The predominant cell type was small round to fusiform dark blue cells. The dark blue cells formed distinct epithelial cords with gland-like formations with mucicarmine-positive mucus. Another distinctive component of the tumors was a mesenchymal one. The mesenchymal areas appeared benign and could be likened to a fibroma having a densely collagenous stroma, or they had spindle cells set in the myxoid background, rendering a myxoma-like appearance. Another distinctive feature was ganglion cell differentiation. Mitotic figures, including atypical forms, were found only in the small cell component. All cells were immunohistochemically negative for actin, calponin, desmin, HMB45, neurofilament protein, CD99/MIC2, Melan A, tyrosinase, serotonin, CD56, Melan A, GFAP, and S-100 protein. Cytokeratin, synaptophysin, FLI1 protein, and chromogranin antibodies reacted only in the primitive small round cells, while all the other components were cytokeratin negative. Fluorescence in situ hybridization showed that the tumors are without the EWSR1 gene translocation and gain 12p. Ultrastructurally, the cells were endowed with well-formed intercellular desmosomes membrane-bound secretory in the cytoplasm. Granules were found in the cytoplasm. We suggest the name "primitive small cell tumor with epithelial, gangliocytic, neuroendocrine, and mesenchymal differentiation" for this neoplasm.
authors.affiliation: Sikl's Department of Pathology, Charles University, Medical Faculty Hospital, Alej Svobody 80, 304 60 Pilsen, Czech Republic. michal@medima.cz
authors.forename: Michal
authors.initials: M
authors.lastname: Michal
authors.forename: Dmitry V
authors.initials: DV
authors.lastname: Kazakov
authors.forename: Radek
authors.initials: R
authors.lastname: Síma
authors.forename: Tomás
authors.initials: T
authors.lastname: Vanecek
mesh_terms: D000782:Aneuploidy; D014408:Biomarkers, Tumor / Q000378:metabolism; D018288:Carcinoma, Small Cell / Q000235:genetics / Q000378:metabolism / Q000473:pathology* / Q000628:therapy; D002471:Cell Transformation, Neoplastic; D002675:Child, Preschool; D002881:Chromosomes, Human, Pair 12; D003131:Combined Modality Therapy; D003896:Desmosomes / Q000648:ultrastructure; D004847:Epithelial Cells / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D046529:Microscopy, Electron, Transmission; D018358:Neuroendocrine Tumors / Q000235:genetics / Q000378:metabolism / Q000473:pathology* / Q000628:therapy; D018228:Sarcoma, Small Cell / Q000235:genetics / Q000378:metabolism / Q000473:pathology* / Q000628:therapy; D022142:Secretory Vesicles / Q000648:ultrastructure; D012983:Soft Tissue Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology* / Q000628:therapy
chemical_list: D014408:Biomarkers, Tumor