Erdheim-Chester disease presenting with multisystem involvement: A case report

BACKGROUND Erdheim-Chester disease (ECD) is an ultra-rare non-Langerhans cell histiocytosis driven by clonal proliferation of lipid-laden histiocytes. With fewer than a thousand documented cases globally, it remains largely unreported in South Asia. CASE SUMMARY A 46-year-old male presented with chronic leg pain, polyuria, and visual disturbances. Radiologic findings revealed symmetric osteosclerosis of long bones and absent pituitary shadow with thickened stalk of pituitary gland. Histopathology showed foamy histiocytes positive for CD68 and CD163 but negative for CD1a and Langerin. Detection of BRAF V600E mutation confirmed the diagnosis. The patient was treated with corticosteroids and interferon-alpha, with significant symptomatic improvement at six months. CONCLUSION This case represents the first case of ECD reported from Pakistan. Awareness of its distinct imaging and histologic patterns can facilitate diagnosis even in resource-limited settings. National rare disease registries and access to molecular diagnostics are essential for improving outcomes.