Thyroid-like cholangiocarcinoma of the liver: an unusual morphologic variant with follicular, trabecular and insular patterns.

We report the case of a 26-year-old woman with a 19 cm malignant hepatic neoplasm with morphological features that closely resembled a follicular thyroid carcinoma. Despite this, it was interpreted as a cholangiocarcinoma due to the absence of a primary thyroid tumor and the lack of thyroglobulin and TTF-1 immunoreactivity by the hepatic tumor. The left hepatic lobectomy specimen showed an encapsulated and multinodular gray-white mass with cystic and hemorrhagic areas. Microscopically, it displayed predominant macro and microfolicullar patterns with focal solid, trabecular and insular areas. The small and distended follicles contained a colloid-like secretion and were lined by low cuboidal cells with scant cytoplasm, round or oval hyperchromatic nuclei with fine chromatin. The solid areas, trabecular and insular structures were similar to those of follicular or papillary thyroid carcinomas. In addition, some of the neoplastic cells had clear nuclei with occasional grooves. The tumor was positive for cytokeratin (CK) 7, CK 19 and CD138, and negative for TTF-1, thyroglobulin, Hepar-1, Glypican-3, alpha-fetoprotein and neuroendocrine markers. A thyroid neoplasm was excluded clinically and by ultrasound and computed tomography. Although, the residual hepatic parenchyma was initially not cirrhotic, the patient eventually developed cryptogenic cirrhosis. The patient received adjuvant chemotherapy and died of metastatic disease 18 months after surgery. The thyroid-like pattern broadens the morphologic spectrum of cholangiocarcinoma.