Endocrine Abstracts

Introduction

Langerhans cell histiocytosis (LCH) is a rare monoclonal disease characterized by abnormal proliferation and accumulation of bone marrow-derived Langerhans cells in various tissues. Heterogeneous collections of Langerhans cells with neutrophils, lymphocytes, eosinophils, histiocytes and Birbeck granules are observed in biopsy materials. Endocrinologic features of LCH are usually due to posterior pituitary involvement. Thyroid infiltration is rare and LCH confined only to thyroid gland is even a rarer condition. Here in we present a care with isolated thyroid LCH presenting with Graves’ disease. (GD)

Case Presentation

A 41-year-old, 21 weeks pregnant, patient was referred to the endocrinology clinic because of hyperthyroidism. She had been followed up with the diagnosis of GD for 3 years and received methimazole treatment. With pregnancy her treatment was switched to PTU in the first trimestr Her test results were as follows TRAb 2.55 (<1.75 U/l), TSH 0.017 (0.27–4.20 mIU/l); FT3: 5.23 (2–4.4 pg/ml); FT4: 1.96 (0.93–1.70 ng/dl). Ultrasound showed diffused hypoechogenicity and enlargement in both sides of thyroid. A 12×11 mm hypoechoic nodule on the right and a 11*7.6 mm hypoechoic nodule on the left were detected. Upon completion of her pregnancy total thyroidectomy was performed due to on going GD. Pathologic examination revealed langerhans cell histiocytes which were positive for Langerin, S-100, CD1a in immunohistochemical staining. There was concomitant diffuse hyperplasia of the thyroid gland. With all these result was consisted with LCH and GD of the thyroid gland. Bone marrow aspiration biopsy, contrasted cranial MRI and PET-CT ruled out multisystemic involvement of LCH. After thyroidectomy she is followed with LT4 treatment. No additional systemic treatment was required due to local involvement of LCH. Her medical condition is stable under thyroid hormone replacement therapy.

Discussion

Thyroid involvement of LCH is a rare condition and of those with thyroid involvement only 1.5% present with subclinical hyperthyroidism.(1). Number of cases with LCH related with GD has been rarely reported in literature. Here in we report a case with isolated thyroid LCH who first presented with GD. We speculate that immunologic changes due to LCH may trigger autoimmunity which subsequently may cause GD.