Filamentous inclusions of unusual composition and architecture in a metastatic tumor showing myoepithelial differentiation.
A hyaline/eosinophilic cytoplasmic inclusion is described in a metastatic tumor occurring in the omentum and bowel of a 32-year-old white woman. The tumor was essentially of round cell type; was positive for cytokeratin, actin, and S-100 protein by immunohistochemistry; and showed desmosomes (maculae adherentes), tonofibrils, modestly developed myofilaments with focal densities, and a basal lamina by electron microscopy. It was therefore interpreted as showing myoepithelial differentiation. Nearly all cells possessed a large, rounded cytoplasmic inclusion that was architecturally unusual, consisting of intermediate filaments intermingled with lattices of fine filaments. The inclusions exhibited an additionally unusual immunohistochemical staining for both cytokeratin and actin. A comparison with cases described in the literature is made.
Eyden
B
B
Department of Histopathology, Christie Hospital, Manchester, United Kingdom.
Dardick
I
I
Bishop
P
P
D000328:Adult; D002277:Carcinoma / Q000473:pathology* / Q000601:surgery / Q000648:ultrastructure; D002454:Cell Differentiation; D005260:Female; D006801:Humans; D002479:Inclusion Bodies / Q000648:ultrastructure*; D007414:Intestinal Neoplasms / Q000473:pathology* / Q000556:secondary / Q000601:surgery / Q000648:ultrastructure; D009362:Neoplasm Metastasis / Q000473:pathology* / Q000648:ultrastructure; D016896:Treatment Outcome