Anthracofibrosis is luminal narrowing with a black anthracotic pigmentation on the bronchial mucosa. Extrapulmonary anthracofibrosis is very rare in head and neck region, and anthracofibrosis associated withadhesion to adjacent tissue can be misdiagnosed to malignancy. We report a rare case of a paraesophagealanthracofibrosis in a patient with advanced papillary thyroid cancer. The paraesophageal anthracofibrosispresented as a black colored hard mass with severe adhesion to the recurrent laryngeal nerve (RLN) during thyroidsurgery, suspecting metastatic lymphadenopathy. With intraoperative frozen biopsy, unnecessary aggressivesurgery with the injury of RLN can be avoided. Permanent histopathological examination of the mass revealedanthracofibrosis with strong positivity on Masson’s trichrome staining. This case highlights that anthracofibrosisshould be included in differential diagnosis of paraesophageal masses, and frozen sectional biopsy can help indecision making during surgery. In addition, collagen might be involved in the adhesion of the anthracotic massto the surrounding tissues.