Synchronous Thyrolipoma and Papillary Thyroid Carcinoma: A Rare but Significant Event

The presence of adipocytes within thyroid glands is a rare finding seen in thyrolipoma, diffuse lipomatosis, or thyroid teratoma. Although some cases present with multinodular goiter or autoimmune thyroiditis, the exact cause has not yet been elucidated. Among reported cases, thyrolipomas mainly occur in females and usually present as a solitary lesion. However, a few reported cases had coexisting papillary thyroid carcinomas. Herein, we present a 51-year-old female with synchronous thyrolipoma (2.0 × 1.5 × 1.3 cm) and papillary thyroid carcinoma (0.7 × 0.6 × 0.6 cm) within the same thyroid lobe. She had diabetes mellitus and hypertension and complained of anterior neck enlargement and discomfort for three months. Thyroid sonography showed multiple hypoechoic nodules, one of which was heterogeneous and ill-defined. Fine needle aspirate cytology for the ill-defined nodule was suspicious for papillary thyroid carcinoma. She subsequently received radical thyroidectomy and neck lymph node dissection. Histopathologically, one thyrolipoma and one papillary thyroid carcinoma were identified in the right lobe of the thyroid gland without metastases of lymph nodes, while other nodules were multinodular goiter. Notably, thyrolipoma may not be simply an incidental finding but might coexist with thyroid carcinomas. A brief review of the pertinent literature of prior reports is also provided.