Endocrine Abstracts

A 25-year old woman with Hashimoto thyroiditis was referred to the endocrinology department for investigation of a 40 kilogram weight gain, polyuria, polydipsia and secondary amenorrhea. Hormonal work-up showed diabetes insipidus, central hypogonadism, secondary adrenal insufficiency, central hypothyroidism and slight hyperprolactinemia. Pituitary magnetic resonance imaging (MRI) revealed a 15 mm hypothalamic tumor expanding to the infundibulum, associated with pituitary stalk thickening. Serum and cerebrospinal fluid tumor markers were negative and without evidence of infiltrative disease. Extensive whole body imaging was unremarkable except for high uptake of the suprasellar lesion (SUV 11.8) on 18F-fluorodeoxyglucose positron emission tomography and computed tomography (FDG-PET/CT). The patient refused transcranial biopsy for fear of potential complications. Due to mildly increased angiotensin-converting-enzyme and 24-hour urine calcium, neurosarcoidosis was suspected and prednisone was initiated (1 mg/kg) then stopped because of side effects (uncontrolled diabetes and weight gain) and the absence of radiologic improvement. Methotrexate was then prescribed and continued for a year. One year later, FDG-PET revealed high FDG uptake of the thyroid gland (SUV 4.1), which was also present at baseline and attributed to Hashimoto thyroiditis. Thyroid ultrasound showed heterogeneous pattern with slightly increased vascularity. On follow-up, thyroid parenchyma showed marked changes with intense hypoechoic pattern and decreased vascularity. Fine-needle aspiration (FNA) of the thyroid gland was then decided and cytology showed a proliferation of Langerhans cells with deeply grooved nuclei admixed with eosinophils. The Langerhans cells were strongly positive for CD1a by immunocytochemistry. Cladribin treatment was initiated and resulted in a significant decrease in tumor size within 2 months (craniocaudal axis on MRI: 19 mm versus 24 mm at baseline). Histiocytosis includes a group of syndromes characterized by tissue infiltration of histiocytes thought to be derived from dendritic cells or macrophages that may infiltrate various organs, notably the central nervous system. Thyroid involvement has rarely been reported, is more common in adults and is usually related to multi-systemic disease. Ultrasound shows hypoechoic pattern, heterogeneity and rare calcifications. Thyroid FNA can be useful in establishing the primary diagnosis if no other tissue biopsy can be done and immunohistochemical staining shows positivity for S100, CD1a and langerin. Thyroid ultrasound should thus be performed in all patients with intra-cranial tumors suggesting LCH, especially in case of increased FDG-avidity of the thyroid parenchyma. FNA could be systematically considered as being part of the differential diagnosis workup in these cases.