CD44 EXPRESSION IN BENIGN AND MALIGNANT NEVOMELANOCYTIC LESIONS

CD44 is an integral membrane glycoprotein that is a principal receptor for hyaluronan and plays a role in cell-extracellular matrix interact ions. Recent studies of melanomas in mouse models have suggested that increased CD44 expression by these tumors may relate to metastatic pot ential. Immunohistochemical expression of CD44 (standard [s] and varia nt [v6]) in benign and malignant nevomelanocytic lesions was assessed in formalin-fixed, paraffin-embedded tissue and was correlated with hi stological parameters and prognostic factors. Cases included benign ne vi (three junctional, four compound, five intradermal, five blue, six Spitz, one deep penetrating), architecturally disordered (dysplastic) nevi (three, and primary (22) and metastatic melanomas (eight). All of the benign lesions showed diffuse and essentially uniform membrane st aining of CD44s in nevomelanocytic cells, regardless of lesion size, d epth, or extent of dermal involvement. In contrast, semiquantitative a nalysis (0 to 3+) of the primary melanomas showed heterogeneous and de creased staining of CD44s, which inversely correlated with lesion size (-0.569) and depth of invasion (-0.622 and -0.617 for Breslow's depth and Clark's level, respectively. These results were significant at P< .05. CD44s expression in metastases paralleled that of their respectiv e primaries. None of the benign nevomelanocytic lesions showed CD44v6 staining. In contrast, all of the malignant nevomelanocytic lesions sh owed cytoplasmic staining of the tumor cells. Pretreatment with chondr oitinase did not alter CD44s staining. CD44s expression by immunohisto chemical determination is uniform in benign nevamelanocytic lesions. M alignant melanomas show decreased, heterogeneous staining that inverse ly correlates with increasing size, depth, and level of invasion. CD44 expression may be a prognostic indicator in malignant melanomas. Tumo r staining with anti-chondroitin sulfate monoclonal antibodies suggest s that CD44s may be expressed as a chondroitin sulfate proteoglycan in primary melanomas. Copyright (C) 1996 by W.B. Saunders Company