Fine-needle aspiration cytology in a rare case of recurrent mucinous carcinoma of skin, displaying psammoma bodies on smears.

Primary mucinous carcinoma of skin is an uncommonly documented tumor, especially on fine-needle aspiration cytology (FNAC) smears. A 58-year-old gentleman presented with a recurrent swelling over his right zygoma. Earlier, he had undergone surgical resection at the same site, on two occasions, 4 years back. FNAC smears from the recurrent nodule displayed clusters and singly scattered relatively monomorphic, polygonal to plasmacytoid cells with mild nuclear atypia and moderate to abundant cytoplasm, including focal intracytoplasmic vacuoles. At places, tumor cells were arranged around psammoma bodies against a background of mucinous material. Histopathological sections from the subsequent tumor resection revealed tumor cells arranged in the form of islands, nests, cribriform, and papillary arrangements amidst mucinous stroma, along with focal psammomatous calcification, consistent with a recurrent mucinous adenocarcinoma. On immunohistochemistry, tumor cells were diffusely positive for CK 7, estrogen receptor (ER), and progesterone receptor (PR), while negative for CDX2, CK20, and TTF1. Diagnosis of a recurrent mucinous carcinoma of skin was offered. Patient underwent adjuvant radiotherapy for achieving better loco regional clearance and is disease-free, 4 months after. FNAC is a useful diagnostic tool for timely identification of mucinous carcinoma of skin, including recurrent lesions. Psammomatous calcification can be identified within this uncommon tumor, in recurrent lesions. While surgical resection remains the treatment mainstay, immunohistochemical expression of ER and PR in this tumor perhaps could have therapeutic impact, especially in recurrent cases.