Histiocytic lesion masquerading as papillary carcinoma thyroid-A case report.

Langerhans cell histiocytosis (LCH) is a rare clonal neoplasm derived from Langerhans-type cells that express CD 1a, langerin, and S 100 on immunohistochemistry. LCH usually involves multiple sites and multiple systems or multiple sites in a single system. Solitary LCH commonly involves the bones (especially the skull), lymph nodes, skin, and lungs. Solitary LCH of the thyroid is an extremely rare disease with a few reported cases in the indexed literature and poses a diagnostic dilemma for both the clinician and pathologist. Histopathology along with ancillary tests forms the gold standard for diagnosis. Surgical resection alone offers a good prognosis once multisystemic involvement has been ruled out. Herein is reported one such case of solitary LCH in a young male patient who remains disease-free after 2 years of follow-up.