An adult patient with hypersensitivity to mosquito bites developing mantle cell lymphoma.

Hypersensitivity to mosquito bites (HMB) has been known to occur exclusively in the first 2 decades of life and is frequently associated with Epstein-Barr virus (EBV) infection and lymphoproliferative diseases. We report here the first adult patient with HMB, a 61-year-old Japanese man who developed mantle cell lymphoma. EBV was detected in the lymph node by polymerase chain reaction and by in situ hybridization. Serum levels of interleukin (IL)-4, IL-6, and IL-10 were markedly increased, and the T-helper cell (Th)1/Th2 balance determined by intracellular cytokine levels was polarized to Th2. These findings suggest that the Th1/Th2 imbalance could partly be involved in the pathogenesis of HMB.