Osteoclastomalike anaplastic carcinoma of the thyroid gland diagnosed by fine needle aspiration cytology. Report of two cases.

Background: Thyroid diseases are common among the female population in Iran; the main one is endemic colloid goiter. Thyromegaly can be due to neoplastic and nonneoplastic disorders. The clinical distinction between benign and malignant tumors of the thyroid gland is sometimes difficult. Fine needle aspiration (FNA) study can be used as a preliminary step for identifying such lesions.
Cases: Two female patients aged 54 and 62 years were admitted to Nemazi Hospital, Shiraz, Iran, with the chief complaint of weight loss, rapid enlargement of the thyroid gland for the last few months and pressure symptoms in the neck. Clinically these cases were diagnosed as malignant thyroid lesions. However, for further diagnosis the tumors were aspirated. The smears revealed numerous osteoclastlike giant cells with intranuclear inclusions and numerous, isolated oval to spindle-shaped malignant cells. The smears were diagnosed as osteoclastlike anaplastic carcinoma of the thyroid.
Conclusion: FNA is useful in the diagnosis of osteoclastomalike anaplastic carcinoma of the thyroid.