Delayed diagnosis of pituitary LCH with BRAFV600E mutation: A case report and literature review.

RATIONALE: This case report highlights the diagnostic challenges and clinical complexities of adult-onset pituitary Langerhans Cell Histiocytosis (LCH), a rare entity with a prolonged and indolent progression. This underscores the critical need for heightened clinical suspicion in patients with chronic endocrine dysfunction, particularly in those with multisystem comorbidities. The atypical 10-year diagnostic odyssey coupled with molecular confirmation of the BRAFV600E mutation adds novel insights into delayed recognition and genetic markers in adult LCH, addressing gaps in the existing literature on protracted pituitary involvement. PATIENT CONCERNS: A 38-year-old woman experienced decade-long polydipsia, polyuria, fatigue, irregular menstruation and progressive panhypopituitarism. Laboratory findings showed hypernatremia (Na 155.7-157.5 mmol/L), hyperchloremia (Cl 113.6-119.1 mmol/L), low TSH (0.015-0.144 µIU/mL) with low-to-normal FT3/FT4, persistently low cortisol, low FSH/LH, and low PRL. MRI revealed a 1.9 × 1.4 × 1.2 cm pituitary mass. DIAGNOSIS: Pituitary LCH was confirmed by nasal saddle area biopsy (S100/CD1a positivity) and BRAFV600E mutation detection via ARMS-PCR. INTERVENTIONS: Management included desmopressin, glucocorticoid and thyroid hormone replacement, and LCH-III-based chemotherapy with prednisone and vincristine. Mercaptopurine (6-MP) was omitted due to hepatic dysfunction. However, chemotherapy was complicated by hepatic dysfunction, osteoporosis, and type 2 diabetes, which require intermittent cessation of chemotherapy and hepatoprotective therapy. OUTCOMES: Tumor size decreased to 1.0 × 1.2 × 0.7 cm; endocrine deficits persisted, requiring lifelong hormone replacement. The patient's condition stabilized through continuous multidisciplinary care. LESSONS: This case emphasizes that chronic endocrine symptoms warrant prompt pituitary imaging and early molecular testing, including BRAFV600E analysis, to avoid prolonged diagnostic delays and enable tailored therapy - especially in patients with comorbidities limiting standard treatment regimens.