Multicentric reticulohistiocytosis

Multicentric reticulohistiocytosis describes an extremely rare form of non-Langerhans cell histiocytosis. Characteristic of the disease are nodular skin lesions and destructive arthritis. In the 200 known cases, the syndrome started suddenly at the age of about 50 years and had a progressive course.

After the arthritis initially increases in severity, changing phases of deterioration and improvement develop. These have in many cases resulted in debilitating arthritis that can affect a variety of joints, including the hand, shoulder, knee, hip and ankle. After a very variable course of disease develops a deforming arthritis, which is known as mutilating arthritis.

At the same time, the patients show skin nodules, which regress again as new efflorescences develop. The nodules vary between a skin-colored and reddish-brown color and usually cause no pain. Their occurrence can be limited to the upper body and hands, but sometimes also the mucous membranes are affected.

After about 6-8 years, the arthritis sets in, the nodules persist or form back.

It is believed that the syndrome is an exceptionally inflammatory response to unknown triggers involving macrophages and T lymphocytes. In about 25% of patients an additional malignoma was detected at the same time.