Extrarenal rhabdoid tumor

Epithelioid MPNST is an extremely rare tumor variant that also has a histologic resemblance to melanoma, as well as metastatic carcinoma, CCS, and extrarenal rhabdoid tumor (Fig. 4.26). As a result, epithelioid MPNST is underrecognized as a diagnostic entity. 

Extrarenal rhabdoid tumors (ERTs) often show epithelial differentiation, and some may be difficult—if not impossible—to separate diagnostically from such entities as proximal-type epithelioid sarcoma. " INIl, a protein encoded by a gene at chromosome 22qll.2, is involved in chromatin remodeling it is usually absent in both ERT and proximal epithelioid sarcoma, as well as conventional (distal) epithelioid sarcoma. The majority of tumors in each category also show... 

Fanburg-Smith JC, Hengge M, Hengge UR, et al. Extrarenal rhabdoid tumors of soft tissue A clinicopathologic and immunohistochemical study of 18 cases. Ann Diagn Pathol. 1998 2 351-362. 

Oda Y, Tsuneyoshi M. Extrarenal rhabdoid tumors of soft tissue Clinicopathological and molecular genetic review and distinction from other soft-tissue sarcomas with rhabdoid features. Pathol Int. 2006 56 287-295. 

Parham DM, Weeks DA, Beckwith JB. The clinicopathologic spectrum of putative extrarenal rhabdoid tumors. An analysis of 42 cases studied with immunohistochemistry or electron microscopy. Am J Surg Pathol. 1994 18 1010-1029. 

Biegel JA, Tan L, Zhang F et al (2002) Alterations of the hSNF5/INll gene in central nervous system atypical tera-toid/rhabdoid tumors and renal and extrarenal rhabdoid tumors. Clin Cancer Res 8(ll) 3461-3467... 

FIGURE 4.33 The histologic image of extrarenal malignant rhabdoid tumor features large cells with eosinophilic cytoplasm, eccentric vesicular nuclei, and prominent nucleoli. 

Tumors that are histologically identical to malignant rhabdoid tumor of the kidney in children may be encountered in a variety of extrarenal sites in adults, including the soft tissues." The hallmarks of these neoplasms are hyaline paranuclear cytoplasmic eosinophilic inclusions eccentric, rounded nuclei with vesicular chromatin prominent nucleoli (Fig. 4.33) and a complex immunophenotype. 

Malignant rhabdoid tumors of the kidney were described in 1978 by Beckwith and Palmer as highly malignant tumors of infants and children initially thought to represent a variant of Wilms tumor. Similar neoplasms were described in extrarenal sites and in adults. 

MRT (atypical teratoid/rhabdoid tumor) frequently demonstrates deletion and mutation of the hSNF5/INIl gene, with decreased or absent INIl protein expression. An antibody to INIl can be used to assess INIl loss, characterized by absence of immunoreactivity in contrast to functional INIl with positive immunoreactivity in normal tissues and other neoplasms." Like MRT of the kidney and extrarenal soft tissues, atypical teratoid/rhabdoid tumors of the central nervous system showed absence of nuclear staining for INIl in a recent study." 3i... 

T-cell lymphoma, ALCL, AML, GIST, breast metaplastic carcinoma, ovarian sex cord stromal tumors, synovial sarcoma, Merkel cell carcinoma, endocrine and neuroendocrine tumors, desmoplastic small round cell tumor, melanoma, nephroblastoma, ependymoma, mesenchymal chondrosarcoma, extrarenal malignant rhabdoid tumor, rhabdomyosarcoma, meningeal... 

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