Pulmonary metastasis of cribriform‐morular variant of thyroid carcinoma mimicking primary adenocarcinoma of the lung: A potential pitfall

Cribriform‐morular variant of papillary thyroid carcinoma (CMV‐TC) shows a peculiar mixture of follicular, cribriform, papillary, trabecular, and solid patterns with squamoid morules. Ocassionally, lung metastasis may be interpreted incorrectly as primary lung adenocarcinoma. We illustrate a case of pulmonary meastasis of CMV‐TC mimicking a primary adenocarcinoma, 7 years after diagnosis of CMV‐TC. The lung metastases may be easily missed if the pathologist is unaware of the patient's prior history and a limited immunohistochemical panel (CK7 and TTF‐1) is used. The histologic and immunohistochemical (β‐catenin+, ER+, PR+, TTF‐1 +, and CK7+) findings were diagnostic of CMV‐TC and ensured adequate treatment.