Takashi Taniguchi, Yoshihide Asano, Asako Okada, Makoto Sugaya, Shinichi Sato
DOI: 10.2340/00015555-0961

Multicentric reticulohistiocytosis is a rare systemic disease of unknown aetiology characterized by erosive arthritis and cutaneous lesions consisting of multiple reddish-brown papules and nodules, mainly involving the face and distal upper extremities. It has been suggest­ed that skin eruptions in multicentric reticulohistiocytosis are associated with Köbner phenomenon due to their characteristic distribution, such as on the dorsal aspect­s of the hands and fingers. We report here a case of a Japan­ese woman with multicentric reticulohistiocytosis, in whom erythematous macules and papules were widely distributed over the face, ears, neck and the V-area of the chest. Notably, repeated irradiation of ultra­violet (UV) B on the uninvolved back skin resulted in the induction of erythematous macules with infiltration of reticulohistiocytes, indicating the association of UVB-induced Köbner phenomenon with the development of skin lesions, especially on the sun-exposed area. This is the first known report demonstrating the contribution of UV-light-induced Köbner phenomenon for the develop­ment of skin eruption­s in patients with multicentric reticulo­histiocytosis.