Diagnosis of metastatic malignant melanoma by fine needle aspiration biopsy: a clinical and pathologic correlation of 298 cases.

Fine needle aspiration biopsies (FNABs) from 298 lesions in patients with suspected metastatic melanoma were studied. The results were correlated either with histopathologic diagnoses on resected lesions or with prolonged clinical follow-up. Of 165 malignant aspirates, 160 were confirmed either by surgical resection (65 cases) or by an appropriate clinical course (95 cases). Of the 107 benign lesions with adequate follow-up, 73 were confirmed as benign. There were 25 false negatives: 19 were inadequate samples, and 6 were presumed failures of needle localization. No interpretative errors were identified. Although 3 cases of FNAB-diagnosed malignant melanoma could not be confirmed by surgical biopsy, the cytologic findings were typical of malignant melanoma. Clinical follow-up, however, suggested that the cytologic diagnosis was in error. One case of a second unrelated malignancy (an adenocarcinoma of the lung) was correctly diagnosed with the use of FNAB. Because of its high degree of accuracy, FNAB has proved useful in the differential diagnosis of subcutaneous nodules, enlarged lymph nodes, and lung nodules.