BRAF gene mutations in synchronous papillary thyroid carcinoma and Langerhans cell histiocytosis co-existing in the thyroid gland: a case report and literature review

Langerhans cell histiocytosis (LCH) is a rare clonal disease, characterized by hyperproliferation of Langerhans cells. It may rarely involve the thyroid gland. Its association with papillary thyroid carcinoma (PTC) is extremely rare; with only few case reports available in the English literature. BRAF mutations are implicated in the development of papillary thyroid carcinoma, and have also been identified in Langerhans cell histiocytosis. Here we present a rare case of a 36-year-old Indonesian female patient with dysphagia associated with neck mass which was complicated by skin sinus formation. The diagnosis of PTC was rendered on fine needle aspiration (FNA). Debulking thyroidectomy revealed co-existeence of PTC and LCH. On subsequent molecular testing, BRAF V600E and V600K mutations were detected in tissues macrodissected from both lesions, respectively. To the best of our knowledge, this case is the first case to report two different BRAF mutations in tissues of a Langerhans cell histiocytosis and a papillary thyroid carcinoma co-existing in the thyroid gland. The patient received chemotherapy of etoposide combined with prednisone. At the most recent follow-up, the patient is in a stable clinical condition. The coexistence of a PTC with LCH harboring BRAF mutation may suggest etiologic relation between the two conditions that involves the BRAF gene. Clinically, it may suggest an aggressive, locally advanced thyroid cancer, an impression that may reflect on the selected surgical management, chemotherapy and BRAF mutation-targeting therapy to these patients.