Monoclonal gammopathies and malignancies in patients with chronic urticaria

Monoclonal gammopathy of undetermined significance (MGUS) has been described in association with chronic urticaria (CU) in patients with Schnitzler syndrome. Chronic urticaria may be a manifestation of hematologic malignancies.

This study was conducted to evaluate the frequency and characteristics of MGUS or malignancy in patients with CU. The Mayo Clinic electronic database was reviewed to identify patients with the diagnosis of CU.

Of the 1639 patients presenting with CU between 1994 and 2001, 797 (49%) underwent laboratory evaluation for the presence of a coexisting monoclonal protein. Forty-seven CU patients had MGUS, 142 had a malignancy, and 24 had both. Fifteen percent of CU patients with MGUS had a hematologic malignancy compared with 0.9% of CU patients without MGUS (P < 0.001). Patients presenting with a new diagnosis of CU at an older age (> 56 years) were more likely to have associated underlying MGUS. The occurrence of MGUS in this group was higher than the reported incidence of MGUS in the general population.

Patients with CU younger than 43 years were unlikely to have associated MGUS or malignancy. A higher percentage of patients with CU and MGUS had an associated diagnosis of hematologic malignancy.