History and clinical findings: A 55-year-old female was admitted complaining of musculoskeletal pain and weakness of both lower extremities for a number of years. Due to a hypothalamic mass of unknown aetiology a diabetes insipidus, a gonadotrophic, somatotrophic and a partially corticotrophic insufficiency had developed.
Investigations: Laboratory investigations yielded elevated levels of several inflammatory parameters (C-reactive protein, blood sedimentation rate, fibrinogen and thrombocytes). Serological parameters indicating a systemic rheumatic disorder were absent. X-ray examination revealed combined osteolytic and osteoblastic lesions within the distal parts of both femora and within the proximal portions of both tibiae. MRI showed signal alterations and (99m)Technetium bone scan exhibited a considerably increased uptake. Histopathologically, a biopsy of the left tibia showed multifocal small infiltrates of foamy histiocytes indicating Erdheim-Chester disease (ECD).
Treatment and course: Under treatment with glucocorticosteroids musculoskeletal complaints improved, but re-appeared following dose reduction. A therapeutic trial using methotrexat did not affect the complaints.
Conclusion: The Erdheim-Chester syndrome is considered to belong to diseases with a proliferation of the monocytic-histiocytic and dendritic cellular system. In the presence of symmetric musculoskeletal symptoms associated with osteosclerotic and osteolytic lesions particularly occurring in the long bones of the lower extremities and concomitant with elevated serum markers of inflammation, the Erdheim-Chester disease should be taken into account. To date, no validated therapy exists.