Langerhans cell histiocytosis with concurrent papillary thyroid microcarcinoma

Abstract

Langerhans cell histiocytosis (LCH) is a rare disease, characterised by proliferation of Langerhans cells in various organs. It can present as localised or disseminated disease, with particular predilection for involvement of skin, bone, brain and lungs. Solitary thyroid gland involvement is exceptionally rare, with only a limited number of cases reported in the literature. Here we describe a case of a 45-year-old female with a known history of hypothyroidism, presenting with enlarged multinodular thyroid gland on clinical examination. Ultrasonography showed a 20 mm left lobe thyroid nodule in the lower pole, and pre-operative fine needle aspiration cytology assessment was classified as suspicious for malignancy (Bethesda category 5). The patient underwent left hemi-thyroidectomy with neck dissection. Microscopic examination revealed chronic lymphocytic thyroiditis with two foci of papillary thyroid microcarcinoma (7.5 mm and 0.6 mm) together with adjacent LCH spanning 3.5 mm. Although concomitant papillary thyroid carcinoma and LCH in thyroid is rare, it has recently been increasingly reported. This draws attention to possible association between the aetiology of both disorders, and necessitates thorough histological examination for concurrent papillary thyroid carcinoma and lymphocytic thyroiditis when diagnosis of LCH in thyroid gland is attained.