Metastasis of Follicular Variant of Papillary Thyroid Carcinoma to Scalp, Masquerading As Adnexal Tumor: A Rare Presentation

ABSTRACT A 55-year-old female presented with ulcerated swelling over the scalp. Clinically, the case was diagnosed as adnexal tumor of skin. Fine needle aspiration cytology (FNAC) from the lesion showed characteristic micro-follicles with typical nuclear features of papillary thyroid carcinoma. Later, diligent clinical examination revealed a small thyroid nodule and FNAC from the same, showed similar cytomorphological features, indicating possibility of follicular variant of papillary thyroid carcinoma. Biopsy of the scalp swelling and thyroid nodule confirmed the same. Identification of typical nuclear features in cytology helps in differentiating follicular variant papillary carcinoma from follicular neoplasms and, predominant presence of microfollicles favour follicular variant of papillary thyroid carcinoma (FVPTC). Spread through lymphatic route is common in papillary thyroid carcinoma but haematogenous dissemination leading to cutaneous metastases is rare. A solitary cutaneous lesion may be the first evidence of disseminated malignancy in a patient with occult papillary thyroid carcinoma. KEY WORDS: Follicular variant; Papillary thyroid carcinoma; Fine Needle Aspiration Cytology; Adnexal tumor