[Peripheral T-cell lymphoma presenting with eosinophilia due to interleukin-5 produced by lymphoma cells].

A 72-year-old male was admitted to our hospital to determine the cause of neck lymphadenopathies. He was diagnosed pathologically by a lymph node biopsy as having peripheral T-cell lymphoma (PTCL). He also had developed eosinophilia and his serum concentration of Interleukin-5 (IL-5) was extremely high. Immunostaining of a resected lymph node revealed that there were lymphoma cells which were stained with anti-IL-5 antibody. After 2 courses of CHOP therapy, the lymphadenopathies and eosinophilia disappeared and the concentration of serum IL-5 was normalized. It was suggested that IL-5 produced by lymphoma cells had induced his eosinophilia.