Ultrasound-guided fine needle aspiration cytology of parathyroid lesions. A review of 72 cases

OBJECTIVE: To elucidate the specific cytomorphologic patterns and diagnostic pitfalls in fine needle aspiration cytology (FNAC) of parathyroid lesions. STUDY DESIGN: Seventy-two cases of surgically excised and pathologically verified hyperparathyroidism (20 cases of parathyroid hyperplasia, 51 of parathyroid adenoma and one of parathyroid carcinoma) received preoperative, ultrasound-guided FNAC examination for enlarged parathyroid glands. The smears were reviewed and analyzed. RESULTS: Parathyroid lesions were diagnosed cytologically in 60 cases (83.3%). The presence of colloidlike substance, macrophages or follicular structures in smears led to six cases (8.3%) being misinterpreted as thyroid lesions. The cellularity of the smears was insufficient for interpretation in six cases (8.3%); however, two of these cases were diagnosed by determination of parathyroid hormone (PTH) levels in the fluid. Parathyroid hyperplasia had more tightly cohesive cell clusters with monomorphism, while parathyroid adenoma had more dispersed or loosely cohesive cells with pleomorphism and anisokaryosis. High PTH concentration in an aspirate was noted in all four cases of cystic lesions.