Fine needle aspiration cytology of cutaneous and subcutaneous metastatic deposits from epithelial malignancies. An analysis of 146 cases

OBJECTIVE: To analyze cases suggestive of cutaneous/subcutaneous metastatic deposits from a known carcinoma or as the first manifestation of an unknown carcinoma using fine needle aspiration cytology (FNAC). STUDY DESIGN: The study group consisted of 146 patients (86 males and 60 females) ranging in age from 34 to 82 years. In 135 cases there was a previous history of carcinoma, and in these cases FNAC showed the tumor to be similar to the carcinoma that had been treated by surgery and/or radiotherapy. In 11 patients no tumor had been found previously, and the site of the unknown primary was suggested by immunostaining. Aspirations were performed using a 22-gauge needle. The material was collected in 30% ethyl alcohol, and filter preparations and cell blocks were made. RESULTS: The size of metastatic nodules ranged from 1.5 to 2 cm. The sites of metastases were on the chest wall (n = 35), back (n = 8), abdomen (including umbilicus) (n = 46), head and neck (n = 35), upper extremity (n = 12), lower extremity ((n = 6), penile skin (n = 1) and vulva (n = 3). The sites of known primary carcinomas were breast (n = 39), lung (n = 35), gastrointestinal tract (n = 38), endometrium (n = 2), cervix (n = 3), urinary tract (n = 4), prostate (n = 3), hand (n = 1), scalp (n = 1), tongue (n = 1), brain (n = 1), ear (n = 3) and ovary (n = 4). The sites of primary carcinomas unknown at the time of aspiration and found after FNAC were the gastrointestinal tract (n = 3), lung (n = 2), prostate (n = 1), breast (n = 3), liver (n = 1) and kidney (n = 1). No false negatives or positives were observed, and no second primary tumors were found. Cytologic preparations were sufficient for diagnosis and typing in tumors with a known primary tumor. Immunostaining was helpful in establishing a diagnosis of carcinoma and in determining the likely primary site in tumors with unknown primaries. CONCLUSION: Cutaneous and subcutaneous metastatic deposits from previously known carcinomas can be diagnosed rapidly and accurately utilizing FNAC. A combination of FNAC and immunostaining may also help define the site of an unknown primary.