CD44 AND MELANOCYTIC TUMORS - A POSSIBLE ROLE FOR STANDARD CD44 IN THE EPIDERMOTROPIC SPREAD OF MELANOMA

CD44 is a polymorphic family of cell membrane glycoproteins that media te cell-matrix and cell-cell interactions involved in the mechanisms o f tumor invasion and metastasis, and are subject to differential regul ation during normal and malignant cell growth. We have investigated im munohistochemically the expression of CD44S and the variant isoforms C D44v3 and CD44v6 in paraffin-embedded tissue from 5 Spitz nevi, 3 comp ound melanocytic nevi, 2 blue nevi, 6 primary melanomas, 15 cutaneous metastases (three epidermotropic, nine dermal and three ulcerated) and 10 lymph node metastases of melanoma. Melanocytes were extensively po sitive for CD44S in primary melanomas and benign melanocytic prolifera tions. Among 15 cases of cutaneous metastases of melanoma, the three e pidermotropic metastases, as well as one of the three ulcerated ones w ere positive for CD44S. CD44S expression was diminished or totally abs ent in six of the nine dermal metastases, in two of the ulcerated meta stases and in seven of the ten lymph node metastases. CD44v3 and CD44v 6 melanocytic expression was absent in all the lesions studied. Accord ing to our results, selective retention of CD44S expression by melanoc ytes in epidermotropic metastases of melanoma seems to indicate that p reservation of CD44S may contribute to the intraepidermal spread of me lanoma.