Abstract

Hyalinizing trabecular adenoma of the thyroid gland is a rare benign neoplasm predominantly diagnosed in middle-aged women. Carney et al. first described this entity that may mimic paraganglioma, medullary carcinoma and papillary carcinoma in 1987. We describe cytologic and histopathologic features of a case of hyalinizing trabecular adenoma combined with occult papillary carcinoma in the opposite lobe. A 55-year-old woman presented with nontender palpable mass of the right neck for 6 months. The aspirate was cellular and contained small clusters and sheets of epithelial cells with abundant filamentous, vacuolated, and ill-defined cytoplasm. The nuclei were slightly pleomorphic and showed nuclear overlapping, nuclear grooves, and intranuclear cytoplasmic inclusions. Histologic examination showed hyalinizing trabecular adenoma in the right lobe and occult papillary carcinoma in the left lobe.

• Keywords: Thyroid;Fine needle aspiration cytology;Hyalinizing trabecular adenoma;Papillary carcinoma