Osteopenia, osteonecrosis, and mastocytosis.

Systemic mastocytosis has been defined as an abnormal increase in mast cells in tissues other than the skin. We report an unusual case of systemic mastocytosis that was manifested by osteopenia and osteonecrosis, and was associated with pancreatic adenocarcinoma. Our experience suggests that osteopenia and compression fractures may be the presenting features of mastocytosis and that a careful search for a malignancy is warranted in these patients.