Beyond the Pituitary Stalk: Primary Hypothyroidism as a Rare Presentation of Multisystem Langerhans Cell Histiocytosis

Fang Chan Lim; Shireen Siow Leng Lui

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Beyond the Pituitary Stalk: Primary Hypothyroidism as a Rare Presentation of Multisystem Langerhans Cell Histiocytosis

Author: Fang Chan Lim ¹ ; Shireen Siow Leng Lui ²
Author Information

1. Department of Internal Medicine, Hospital Tawau
2. Endocrinology Unit, Department of Internal Medicine, Hospital Queen Elizabeth II
Publication Type:Journal Article
MeSH: Histiocytosis, Langerhans-Cell; Hypothyroidism; Pituitary Gland
From: Journal of the ASEAN Federation of Endocrine Societies 2026;41(S1):102-103
CountryPhilippines
Language:English
Abstract: Introduction:Langerhans cell histiocytosis (LCH) is a clonal proliferative disorder of langerin-positive histiocytes. Endocrine involvement most frequently manifests as central diabetes insipidus or secondary hypothyroidism, caused by infiltration of the hypothalamic-pituitary axis. Conversely, direct infiltration of the thyroid gland leading to primary hypothyroidism is an exceptionally rare clinical entity, particularly when presenting concurrently with central disease.
Case:A 21-year-old female with known right otic and multisystem LCH presented with septic shock secondary to a right ear abscess accompanied by polyuria and polydipsia. Physical examination revealed a palpable goiter. Clinical and biochemical evaluation confirmed central diabetes insipidus with associated anterior hypopituitarism (low adrenocorticotropic hormone, follicle-stimulating hormone, and luteinizing hormone). However, concurrent thyroid function tests demonstrated overt primary hypothyroidism, evidenced by an appropriately elevated thyroid-stimulating hormone (26.19 mIU/L) and low free T4 (5.47 pmol/L), rather than the anticipated secondary hypothyroidism. Neck ultrasound showed diffuse thyroid enlargement with heterogeneous echotexture. Crucially, anti-thyroid peroxidase and anti-thyroglobulin antibodies were both negative, rendering Hashimoto’s thyroiditis highly unlikely. Although the patient declined confirmatory fine-needle aspiration, the constellation of a palpable goiter, characteristic ultrasonographic findings, negative autoimmunity, and active multisystem disease strongly supported a diagnosis of direct histiocytic infiltration of the thyroid gland. She was initiated on appropriate glucocorticoid coverage and subsequent levothyroxine replacement, alongside systemic intravenous cytarabine.
Conclusion:This case highlights a rare, mixed endocrine profile in multisystem LCH, demonstrating that pituitary and direct end-organ infiltration can coexist. Hypothyroidism in LCH patients with established central diabetes insipidus should not be reflexively assumed to be central in origin. A comprehensive diagnostic workup, including autoantibody screening, ultrasound, and ideally histopathological confirmation, is essential to accurately identify primary endocrine failure and guide appropriate clinical management in these complex cases.
Full text:2026080416515622663EP_A149.pdf