WT 1 expression in nevi and melanomas: a marker of melanocytic invasion into the dermis.

BACKGROUND: WT1, first recognized as a tumor suppressor gene involved in the development of Wilms' tumor, may have apparently contradictory findings and functions. As WT1 has been identified as a molecular target for cancer immunotherapy, immunodetection of WT1 in tumor cells has become an essential step in cancer studies. METHODS: We compare the expression of this protein among different types of melanocytic nevi and among stages in primary melanoma progression. Tissue microarrays containing normal tissues and 271 primary melanocytic lesion samples (163 primary melanomas and 108 nevi) were studied by immunohistochemistry using monoclonal antibody against WT1. RESULTS AND DISCUSSION: The present study shows these: 1. WT1 protein is predominantly expressed in the cytoplasm of the neoplastic cells. 2. A higher rate of WT1 staining in melanocytic nevi against melanomas has been observed. 3. WT1 expression is increased in advanced stages of melanoma progression: a significant (p < 0.05) increase of expression of WT1 was detected in vertical cases 46.5% vs. radial cases 16.0%, in high levels of Clark (IV, V) 57.4% vs. low levels (I, II, III) 33.0% and when comparing depth of invasion within thickness subgroups. 4. Finally, this study establishes an association of WT1 protein expression with shorter overall survival in melanoma.

Signet-ring cell dermatofibroma.

Dermatofibroma or cutaneous fibrous histiocytoma is a common benign skin lesion with multiple, distinct histologic variants, including cellular, aneurismal, epithelioid, atypical, lipidized "ankle-type," palisading, and cholesterotic. Although dermatofibromas are considered benign neoplasms, certain variants including cellular and aneurismal ones have shown to have a notable tendency to locally recur after excision. Indeed, although extremely rarely, metastases have been associated with the cellular and aneurysmal/atypical variants. Signet-ring cells are formed by cytoplasmic accumulations of various substances that push the nucleus toward the cellular border. The finding of signet-ring cells in a skin neoplasm always raises the suspicion of metastatic adenocarcinoma, although a number of reports have shown their occurrence in primitive cutaneous neoplasms as well. Signet-ring cell formation, however, has never been described in dermatofibroma. We present, for the first time, a new, distinctive variant of dermatofibroma, so-called signet-ring cell dermatofibroma, in a 16-year-old man with a slowly growing skin tumor on the lateral side of his right leg. Histologic examination demonstrated a striking signet-ring cell appearance of most of the cells in an otherwise fibrohistiocytic looking proliferation. Histochemical and immunohistochemical stainings confirmed the diagnosis of dermatofibroma. The phenomenon described in this case enlarges the histologic spectrum of cutaneous fibrous histiocytoma and may cause substantial differential diagnostic problems.

Ascitis y síndrome constitucional en una mujer de 70 años / Clinicopathological Conference Ascites and constitutional síndrome in a 70-year-old woman

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