Tall cell variant of papillary thyroid carcinoma - A cytohistologic correlation

OBJECTIVE: To identify the cytologic characteristics of the tall cell variant of papillary thyroid carcinoma in fine needle aspiration biopsies and make a cytohistologic correlation. STUDY DESIGN: The study group consisted of six patients subjected to fine needle aspiration biopsy of the thyroid prior to surgical resection of the tumor. RESULTS: Nineteen cases of the tall cell variant were identified in 229 cases of papillary thyroid carcinoma (8.5%) from 1957 to 1993. Six cases had aspirates with tall cells. The patients were females with a median age of 43 years, and all had aggressive neoplastic diseases. The tumors had > 30% tall cells. The fine needle aspiration biopsy findings included nuclear grooves and abundant oxyphilic cytoplasm (100%), pseudonuclear inclusions (83.3%) and ground glass chromatin (67%). The majority of neoplastic cells had a nuclear/cytoplasmic ratio of 1:2. A tadpole shape was observed in noncohesive cells, and a respiratory epithelium-like arrangement was seen in cohesive cells. CONCLUSION: Fine needle aspiration biopsy is the best method of identifying tall cells preoperatively. Nuclear and cytoplasmic changes should be added to make a firm diagnosis of the tall cell variant and to rule out columnar cell carcinoma or squamous metaplasia in goiter or usual thyroid papillary carcinoma.