Role of fine-needle aspiration cytology in evaluation of cutaneous metastases.

Skin is an uncommon site for metastasis. This study was done to evaluate the role of FNAC as an important tool for investigating cutaneous and subcutaneous nodules in patients with known malignancy or as a primary manifestation of an unknown malignancy. All the FNAC done from January 2003 to August 2008 were reviewed (n = 55,556). Ninty-five patients (49 males and 46 females with age range of 4-96 years) with cutaneous/subcutaneous nodules which were diagnosed as metastasis were analyzed. Primary tumors of skin/subcutis were excluded from the study. In our study, 63 out of 95 cases had a known primary malignancy. Of these, five had underlying hematological malignancy and 58 patients had solid organ tumors. Lung carcinoma was seen to metastasize most commonly to skin in males and breast carcinoma in females. The most common site for a cutaneous/subcutaneous metastasis was chest wall [40 followed by abdominal wall (14) and scalp (9)]. Multiple site involvement was also observed (8). In 32 cases primary site was not known. They were most commonly diagnosed as poorly differentiated carcinoma followed by adenocarcinoma. FNAC can diagnose a variety of tumors in the skin and support the diagnosis of a metastasis in case of a known primary and offer a clue to underlying malignancy in case of an occult primary.