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