AN IMMUNOHISTOCHEMICAL STUDY OF LYSOZYME CD-15 (LEU M1), AND GROSS CYSTIC-DISEASE FLUID PROTEIN-15 IN VARIOUS SKIN TUMORS - ASSESSMENT OF THE SPECIFICITY AND SENSITIVITY OF MARKERS OF APOCRINE DIFFERENTIATION

We investigated immunohistochemically the localization of lysozyme and Leu M1 in normal skin, 76 cases of benign sweat gland tumors, 28 case s of malignant sweat gland tumors, 23 cases of extramammary Paget's di sease, 7 cases of sebaceous carcinoma, 6 cases of malignant trichilemm oma, 10 cases of squamous cell carcinoma, and 10 cases of basal cell c arcinoma and compared the results with those for gross cystic disease fluid protein (GCDFP)-15 to assess the sensitivity and specificity of our assay conditions for apocrine differentiation. Normal apocrine gla nds were stained with all three antibodies, while eccrine glands were positive only for GCDFP-15, and other portions of normal skin were not stained with any of the antibodies used. In neoplastic tissue thought to be from apocrine tumors, antibodies raised against lysozyme and GC DFP-15 had a greater specificity (100%) for apocrine differentiation, while Leu M1 had a greater sensitivity (88%). Tissues that were staine d with two or three of these antibodies appeared to exhibit apocrine d ifferentiation. In the tumors examined, the specificity for apocrine d ifferentiation was 92% by these criteria. According to these criteria, some cases of syringocystadenoma papilliferum, primary mucinous carci noma of the skin, and extramammary Paget's disease with underlying ade nocarcinoma showed apocrine differentiation.