Fine-needle aspiration cytology of Hürthle cell carcinoma of the thyroid

Specific criteria for the diagnosis of fine-needle aspiration (FNA) of Hürthle Cell Carcinoma (HCC) have rarely been discussed in the literature. A retrospective review of 35 FNA cases with the diagnosis of Hürthle cell lesion or Hürthle cell neoplasm was performed. In each case, there was a subsequent surgical excision. The FNA specimens were divided according to histologic diagnoses as HCC (12 cases), Hürthle cell adenoma (HCA) (14 cases), and benign nonneoplastic Hürthle cell lesions (BNHCL) (9 cases). Each case was examined using a semiquantitative scoring system for the following 11 features: presence or absence of colloid, lymphocytes, and transgressed blood vessels (each scored 0 or 1); the percentage of nuclear enlargement, small cell dysplasia, large cell dysplasia, nuclear crowding, and cellular dyshesion (each scored 0-3); and age, gender, and size of lesion. When diagnosed by FNA as either Hürthle cell neoplasm or Hürthle cell lesion, males were much more likely to have malignant tumors than females. Statistically significant cytologic features that favored malignant (HCC) over benign lesions (HCA and BNHCL) included small cell dysplasia, large cell dysplasia, nuclear crowding, and cellular dyshesion. The presence of colloid and lymphocytes favored a benign lesion. Nuclear enlargement and large tumor size are significantly more common in neoplasms than BNHCL.