Cribriform-morular variant of thyroid carcinoma (CMV-TC) is an uncommon variant of papillary thyroid carcinoma.1 The immunohistochemical phenotype is thyroid transcription factor (TTF-1+) with focal staining for thyroglobulin, cytokeratin 7 (CK7) and CK19. The hallmark feature, however, is strong staining for β-catenin. CMV-TC metastasizes to the regional lymph nodes in 10% of patients and to distant sites in 6%.2 We report a case of sporadic CMV-TC in a 45-year-old woman with regional lymph node metastases and, 7 years after diagnosis, lung metastases. Thoracic CT showed multiple bilateral nodules measuring up to 2cm in diameter. In 2018, a chest CT scan revealed a significant increase in nodule size and multiple lesions in the left lower lobe (Fig. 1A). The lesions were positive by PET and a lung core biopsy was performed. The immunohistochemical study showed strong, diffuse positivity for β-catenin, TTF-1, ER and PR (Fig. 1B–D), all characteristic findings in CMV-TC.
(A) Thorax computed tomography scan showing bilateral multiple nodules. (B) Tumor cells showing strong, diffuse staining for β-catenin. β-Catenin 400×. (C) Diffuse staining of tumor cell nuclei with thyroid transcription factor (TTF-1). TTF-1, 200×. (D) Tumor cells showing diffuse, strong staining with progesterone receptors. Progesterone receptor, 200×.
