Macrofollicular variant of papillary carcinoma, a potential diagnostic pitfall: A report of two cases including a review of literature
A 33-year-old woman presented with a 5-year history of thyroid nodule. She noted a recent increase in the size of the nodule. Although she had a family history of thyroid disease, there was no history of radiation exposure or prior malignancy. Thyroid stimulating hormone levels were normal.\nAn ultrasound of the thyroid gland showed a 3.9 cm solid, isoechoic nodule almost replacing the right lobe. An ultrasound guided fine needle aspiration (FNA) was performed. Air-dried smears were stained with Diff-Quik and ethanol fixed smears with Papanicolaou stain.\nThe Diff-Quik smears showed abundant thin colloid and moderate amount of follicular cells arranged in a honeycombed and syncytial pattern []. Some of the follicular cells showed nuclear overlapping enlarged round to ovoid nuclei, small prominent nucleoli and few nuclear grooves []. Rare intranuclear inclusions were also identified []. Few multinucleated giant cells were present. Nuclei with fine powdery chromatin pattern and small nucleoli were present on Papanicolaou stained smears []. The FNA was reported as suspicious for papillary thyroid carcinoma.\nA total thyroidectomy was performed. The right lobe weighed 42 g and measured 7.0 cm × 4.2 cm × 3.0 cm. Cut section showed a 4.0 cm × 3.8 cm × 3.0 cm well circumscribed encapsulated tan-pink nodule located at the inferior lobe. Microscopic examination showed an encapsulated tumor with predominance of macrofollicles lined by overlapping follicular cells with enlarged, optically clear nuclei, containing few nuclear grooves and rare intranuclear inclusions. The tumor was positive for Hector Battifora mesothelial cell-1 (HBME-1).