Langerhans cell histiocytosis of the thyroid: a series of seven cases and a review of the literature.

Langerhans cell histiocytosis is a rare disorder, with a few reports describing isolated thyroid gland involvement. We report seven cases, which included four females and three males ranging in age from 2 months to 55 years, with a median age of 37 years. Histologically, the cases demonstrated either diffuse or focal involvement of the thyroid gland by Langerhans cell histiocytes, characterized by bean-shaped, lobated, folded nuclei. In association with the histiocytic infiltrate, there was a prominent eosinophilic cellular component, as well as destruction of the thyroid follicles. All cases occurred in a background of lymphocytic thyroiditis. One case demonstrated adenomatoid nodules, whereas another had a microscopic papillary carcinoma. Immunohistochemical staining demonstrated positive reactivity with S-100 protein, lysozyme, and KP-1. Four patients with isolated thyroid disease, treated by surgical resection alone, are alive without systemic disease from 3 to 19 years after initial presentation. The three patients with systemic disease died within 1 year of the initial diagnosis with disease-related complications. Localized disease portends a favorable prognosis as compared to the thyroid involvement as part of systemic disease.