DP11 A case of Langerhans cell histiocytosis masquerading as lymphocytic hypophysitis and panhypopituitarism

Abstract Langerhans cell histiocytosis (LCH) is a rare disorder, affecting approximately 1 in 560 000 adults, and is characterized by a wide spectrum of clinical presentations. Early disease onset involving concurrent multiple endocrine dysfunctions is exceptionally uncommon (Mendoza ES, Lopez AA, Valdez VAU et al. Adult-onset Langerhans cell histiocytosis presenting with adipsic diabetes insipidus, diabetes mellitus and hypopituitarism: a case report and review of literature. J Clin Transl Endocrinol Case Rep 2015; 1: 1–5). We report a rare case of multisystem LCH in a 24-year-old man who presented with an ulcerated plaque over the axilla and orange papules over the scalp. The patient had a recent diagnosis of diabetes insipidus, thyrotropin deficiency and gonadotropin deficiency, indicative of panhypopituitarism. A diagnostic skin biopsy was performed to further investigate these dermatological manifestations. Histopathological analysis revealed parakeratosis in the epidermis and sheets of medium-sized ovoid cells permeating the dermis. These cells exhibited nuclear grooves, with a small collection of lymphocytes observed adjacent to the infiltrates. Immunohistochemical staining confirmed the ovoid cells were positive for S100, CD1a and CD68, but negative for CD20, CD3, melan-A, p63 and CD30. Most of the cells also demonstrated positivity for cyclin D1. The lymphocytes consisted of a mixed population of B cells and T cells, with T cells predominating. These findings were diagnostic of LCH. Further imaging confirmed multisystem involvement, including the skin, lymph nodes, pituitary gland and temporal bone. The management of his condition was coordinated through a multidisciplinary team approach, including close collaboration with the endocrinology and haematology teams. The patient was initiated on replacement therapy for panhypopituitarism, including hydrocortisone, desmopressin, thyroxine and gonadotropin. Treatment with 12 cycles of single-agent cytarabine achieved complete remission. However, during follow-up, the patient experienced a limited recurrence of cutaneous lesions, which was managed effectively with cycles of high-dose methotrexate. This case highlights the dermatological manifestations and multiorgan involvement of LCH, along with its potential to cause severe endocrine dysfunction. The complexity of this rare condition emphasizes the need for a multidisciplinary approach to manage its aggressive course. Early diagnosis and treatment are crucial, especially in cases affecting high-risk end organs.