Ahmed, Nehaal

Abstract Langerhans cell histiocytosis (LCH) is a rare histiocytic disorder infrequently complicated by delayed-onset pituitary disease. A 41-year-old female presented with papular, acneiform skin lesions. Shave biopsy demonstrated a superficial dermal epithelioid cell proliferation with S100, CD1a, and langerin positivity on immunohistochemistry and a BRAF p.N486_P490del inframe deletion-gain of function pathogenic variant on next-generation sequencing. The skin lesions spontaneously resolved. One year later, she developed progressive fatigue, fevers, anorexia, menstrual irregularities, polyuria, and polydipsia. Laboratory workup was consistent with panhypopituitarism. Pituitary magnetic resonance imaging noted mass-like thickening and enhancement of the infundibulum extending toward the hypothalamus. After treatment with cobimetinib, magnetic resonance imaging findings resolved but endocrinopathies persisted, requiring indefinite hormone therapy. This case demonstrates the full spectrum of endocrinopathies of LCH-induced pituitary disease and is an unusual circumstance of LCH with delayed-onset panhypopituitarism.