Extensive squamous metaplasia in nodular goiter--a diagnostic dilemma in the fine needle aspiration (FNA) cytology--a case report.

Metaplastic changes are commonly found at widespread locations occurring in both reactive and neoplastic conditions. They can simulate tumors histologically. Squamous metaplasia is rarely seen in areas of fibrosis and inflammation secondary to hemorrhage in nodular goiters. If it is extensive with associated degenerative changes and present clinically in the form of a nodule, cytopathologist must take care to differentiate this from primary or metastatic squamous cell carcinoma or even anaplastic carcinoma.