[Systemic mastocytosis: bone impact].

Systemic mastocytosis is a disease characterized by accumulation of mast cells in various organs of which the most affected is the skin. The bone impact of this disease is very rare and generally associated with the development of secondary osteoporosis with or without fractures. We present three cases of patients with skin mastocytosis lesions and different bone manifestations; the first case was a 51 year old woman in whom we observed a rare sclerosing variant with a normal-high bone density and increased density presented in several vertebrae x-rays. An iliac crest biopsy confirmed bone involvement of the underlying disease. The second case was a 57 year old woman who had characteristic signs of systemic mastocytosis with diarrhea, gastritis, flushes and specific cutaneous reactions to exposure to allergens. She also presented severe decrease in bone mineral density in both lumbar spine and femoral neck, with biochemical parameters of increased bone resorption, so had to be treated with bisphosphonates. The third patient, a 67-year-old woman, had several vertebral fractures, with slightly decreased bone densitometry. This last patient showed a hiperplaquetosis with histological diagnosis of essential thrombocythemia, a picture usually associated with systemic mastocytosis. In conclution, we present and discuss three different bone variants of systemic mastocytosis.