multi-centric reticulohistiocytosis
Multicentric reticulohistiocytosis (MRH), also known as lipoid dermatoarthritis, is a rare systemic disorder.
Epidemiology
The exact prevalence is not known, but the condition is considered to be very rare . It has a slight female preponderance .
Associations
There is a recognized associated with various malignancies (up to 25% of cases ).
Clinical presentation
The two most common and characteristic manifestations are :
- symmetric, erosive, deforming polyarthritis, typically affecting the hands but can also involve other small joints and also larger joints
- papulonodular skin lesions, particularly periungual lesions
Pathology
Multicentric reticulohistiocytosis is considered a form of granulomatous disease characterized by infiltration of multinucleated histiocytes into various tissues, primarily affecting skin and synovium, which results in an erosive, deforming polyarthritis.
Radiographic features
Skeletal
It can have similar plain film findings as gout and rheumatoid arthritis, although it is, unlike these two other conditions, associated with joint space widening.
Features are bilateral and symmetric and include:
- sharply demarcated marginal erosions: can have a strikingly bilateral symmetrical distribution and is often sharply circumscribed and rapidly progressive
- nodular soft tissue swelling: may be appreciated as prominent, non-calcified nodules of the skin, subcutaneous tissue and tendon sheaths
- predisposition for interphalangeal joints
- there can be a tendency toward early and severe atlantoaxial involvement
- no or mild periarticular osteopenia (unlike rheumatoid arthritis)
- often a disproportion between severity of joint destruction and mildness of symptoms regardless of therapy
- absent or minimal periosteal reaction
Treatment and prognosis
Management is typically challenging and successful treatment regimens are only guided by case reports and series given the rarity of the condition . Various DMARDs have been used with varying degrees of success .