Follicular Cell Derived Thyroid Carcinoma: Common Things Present in Uncommon Ways

Abstract

Follicular cell derived thyroid carcinomas, including papillary thyroid carcinoma and follicular thyroid carcinoma, are common in daily pathology practice and the incidence of this entity is dramatically increased due to the wide application of more sensitive diagnostic procedures. However, uncommon presentations of thyroid cancers can be seen occasionally and without awareness of those scenarios, traps, and pitfalls that can easily compromise the patient's care. We reviewed the English literature through PubMed search based on three uncommon presentations identified during our routine diagnostic service for patients with or without thyroid nodules: (1) Phosphatase and tensin homolog immunoreactivity loss initially identified on common follicular nodules, and follicular thyroid carcinoma leading to the identification of a phosphatase and tensin homolog hamartoma tumor syndrome, (2) metastatic thyroid carcinoma incidentally identified in the specimens of neck lymph node dissection of head and neck squamous cell carcinoma, and (3) a papillary thyroid carcinoma incidentally identified in the specimen of laterally located thyroglossal duct cyst. We discussed the representative case scenarios, which include clinicopathologic, immunophenotypic, some with genomic features, diagnostic pearls, and patient management. Follicular cell-derived thyroid carcinoma is commonly diagnosed at a younger age than most other adult cancers. The awareness of those pitfalls would significantly improve the diagnostic accuracy leading to better patient outcomes.