[485] Desmoplastic Melanoma: Expression of Epithelial-Mesenchymal Transition-Related Proteins.

Maria C Garrido-Ruiz, Luis Requena, Heinz Kutzner, Ana B Enguita, Rafa Navas, Jose L Rodriguez-Peralto. University Hospital 12 de Octubre, Madrid, Spain; Fundación Jimenez Díaz, Madrid, Spain; Dermatopathologie Bodensee, Siemensstrasse, Friedrichshafen, Germany

Background: Desmoplastic melanoma is a rare variant of melanoma, clinically ambiguous, appearing as an amelanotic, indurated plaque or mass in sun-damaged skin of elderly patients. Histologically, it's usually characterized by a poorly demarcated neoplasm composed by fusiform melanocytes dispersed in a prominent collagenous stroma, although a phenotypic heterogeneity is widely recognized. It often represents a diagnostic challenge, delaying its detection. Since a better prognosis seems to be associated to this subtype of melanoma compared to conventional non-desmoplastic melanomas, refining its knowledge should lead to its improved and more effective management.
Design: To better understand the biological mechanisms implied in desmoplastic melanomas invasion, we analysed the expression profile of 29 (28 “pure” and 1 “combined”) of desmoplastic melanomas. These data were compared to a series of 62 primary vertical growth phase non-desmoplastic melanomas using a set of proteins including melanocytic markers (S-100 protein and Melan-A) and epithelial-mesenchymal transition-related proteins (E-cadherin, N-cadherin, SPARC, WT1, and PKCα).
Results: The melanocytic origin of desmoplastic melanoma was confirmed by immunopositivity of the spindle cells for S-100. N-cadherin was highly expressed in desmoplastic melanomas (61%), while a weaker expression was observed in conventional melanomas (28%). In contrast, a lower positivity was showed in desmoplastic melanomas for E-cadherin (14%; p<0.05) compared with non-desmoplastic tumors (61%). SPARC) and WT1, previously well recognized to have an important role in local invasion have shown to be significantly overexpressed in desmoplastic melanomas (82% and 71% respectively) compared to conventional melanomas (43% and 47% respectively; p<0.05).

No statistically significant difference was demonstrated for PKCα.
Conclusions: The study demonstrates, for the first time, a prominent expression of epithelial-mesenchymal transition-related proteins in desmoplastic melanomas. However, the better prognosis attributable for desmoplastic versus non-desmoplastic melanomas of the same thickness remains to be explained.
Category: Dermatopathology

Monday, February 28, 2011 2:45 PM

Platform Session: Section F, Monday Afternoon


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