Insect bite-like reaction with bullous lesions mimicking bullous pemphigoid in a patient with chronic lymphocytic leukemia

Patients with chronic lymphocytic leukemia (CLL) rarely exhibit an exaggerated insect bite-like reaction without a history of an arthropod bite. We report a case of an insect bite-like reaction in a 74-year old man with CLL. The patient presented with a 2-year history of recurrent itchy erythematous patches and blisters on the whole body. He had been diagnosed with CLL 2 years ago, and the skin lesions developed 1 month after remission. The result of a skin biopsy was consistent with insect bite. Immunohistochemical staining of the infiltrated cells showed positive reactions for CD3, CD5 and negative for CD20, CD23. Direct and indirect immunofluorescence revealed negative results. The patient was treated with oral prednisolone and dapsone, under the diagnosis of CLL-associated insect bite-like reaction, and showed marked improvement. Dermatologist should be aware of insect bite-like reaction associated with CLL as a distinct disease entity that is similar to insect bite or bullous pemphigoid.