Successful treatment of osteoporosis in systemic mastocytosis with interferon alpha-2b.

Osteoporosis is frequently seen in systemic mastocytosis. Although diphosphonate therapy has been shown to be transiently effective, therapy options for this form of osteopenia are very limited. We have treated three patients with systemic mastocytosis and osteopenia successfully with interferon alpha-2b. Two patients had urticaria pigmentosa and two severe back pain due to vertebral compression fractures. All patients received a daily interferon dose of 3 x 5 mio units/week s.c. for a period of 6 months. Therapy was well tolerated, and back pain resolved in both patients. A marked decrease of mast cell numbers in the bone marrow and a significant increase of bone mineralization and bone density was observed in all patients. Our data suggest that alpha interferon may be a new treatment option for osteopenia in systemic mastocytosis.