Urticaria pigmentosa coexisting with multiple myeloma.

We present the case of a 44-year-old white male who developed multiple myeloma complicated by acute renal failure 8 years after the onset of urticaria pigmentosa. Mast cell disease has been associated with a number of haematological malignancies, particularly those from the myeloid lineage. Lymphoproliferative disorders have also been linked with mast cell disease but an association with multiple myeloma has not previously been described. Patients with urticaria pigmentosa should undergo simple screening blood tests to exclude an underlying haematological malignancy.