Multicentric reticulohistiocytosis revealing a ductal breast cancer in situ: A case report with dermoscopic and histopathological findings.

Multicentric reticulohistiocytosis is a rare non-Langerhans cell histiocytosis of unknown etiology. It is classified as multicentric because of multisystem involvement. The disease predominantly affects the skin and joints, but visceral involvement is possible. Multiple erythematous-brownish, pruritic nodules and papules on the face, hands, neck, and trunk are characteristic. It is associated with autoimmune diseases, or malignant neoplasms are seen in 20% to 30% of patients with multicentric reticulohistiocytosis. The diagnosis is based on histopathology of affected tissues. As it is an underreported disease, there is no standardized treatment. A case of multicentric reticulohistiocytosis is reported as a paraneoplastic manifestation of ductal breast cancer, being successfully treated with no recurrence after two years of follow-up. Few cases of multicentric reticulohistiocytosis associated with breast cancer have been reported in the literature.