Assessment of biopsy techniques and histopathologic interpretations of primary cutaneous malignant melanoma.

The biopsy techniques utilized for diagnosis in 1,161 patients with primary cutaneous malignant melanoma treated at the New York University Medical Center were reviewed. Eight hundred sixty-four (74%) biopsies were of the excisional type and 269 (23%) were incisional. Twenty-eight biopsies (3%) could not be assessed. Two hundred fifty-two consecutive patients referred for treatment of malignant melanoma to the authors for the last three years were studied to determine whether standard techniques of biopsy and uniform criteria for histopathologic diagnosis and staging were being utilized. One hundred forty-nine of these patients (59%) had total excisional biopsies of their lesions and 103 (41%) had incisional biopsies. Of the latter group, 66 (64%) were for lesions less than 2 cm in diameter and were situated in areas other than the face. The biopsy specimens obtained from 123 patients were reviewed by at least one other pathologist as well as our own (A.B.A.). For these 123 patients a difference of histologic diagnosis between pathologists occurred in 11 (9%). In 58 (47%) there was a discrepancy in assignment of Clark levels or a failure to assess Clark levels. Tumor thicknesses as measured by Breslow were read in only 22 (18%) of these 123 patients. The inadequacies of many of the biopsy specimens and discrepancies in histopathologic interpretation indicate that acceptable biopsy techniques and reproducible diagnostic criteria have not yet been generally adapted for primary cutaneous malignant melanomas.