A CASE OF BURNT OUT LANGERHANS CELL HISTIOCYTOSIS PRESENTING AS POST-PARTUM HYPOPITUITARISM

Abstract

Objective: Hypopituitarism in post-partum women is usually attributed to lymphocytic hypophysitis (LH), but can also be secondary to systemic pathology. We discuss a case of a lady presenting with central hypogonadism and diabetes insipidus, who further developed persistent cough, leading to an unexpected diagnosis of burnt-out Langerhans’ cell histiocytosis (LCH). Methods: Clinical and laboratory endocrine evaluation, magnetic resonance imaging (MRI), high-resolution computed tomography (HRCT) and open-lung biopsy results are discussed. Results: A 28 year old lady, presented at 10 months postpartum with polydipsia, polyuria and amenorrhoea for 3 months. Her results showed prolactin of 25 (reference,<23.5) μg/L , oestrogen of 24.8 (reference,30–49), follicular stimulating hormone 6 (reference, 2–20) IU/L and luteinizing hormone 6 (reference, 2–70) IU/L. Water deprivation test demonstrated sodium 148 (reference, 135–145) mEq/l, serum osmolality 310 (reference, 275–295) mmol/kg and urine osmolality 107 (reference,50–1450) mmol/kg improving to 142 mEq/L, 295mEq/L and 535 mEq/L respectively, after desmopressin. Gadolinium enhanced pituitary MRI demonstrated a markedly thickened stalk with uniform enhancement. Chest HRCT confirmed bilateral upper zone cystic lung disease suggestive of either pulmonary lymphangioleiomyomatosis (PLAM) or LCH. Eventual histology showed CD1a-positive burnt-out LCH. This differentiation was crucial as PLAM exacerbates with oestrogen therapy and pregnancy which she was able to successfully pursue without disease exacerbation. Conclusion: The patient’s initial presentation was considered as LH, but subsequent cystic changes on HRCT led to a unifying definitive diagnosis of burnt-out LCH. This case highlights the importance of investigating for uncommon secondary causes of hypophysitis.