Exaggerated insect bite reaction exacerbated by a pyogenic infection in a patient with chronic lymphocytic leukaemia

A 69-year-old woman with chronic lymphocytic leukaemia presented with an 18-month history of pruritic, tender, erythematous plaques. The recurrent lesions simulated insect bites and cellulitis, but failed to respond to appropriate treatments. A recent severe flare was associated with markedly elevated inflammatory markers and swelling of the left leg. The swelling settled rapidly with ibuprofen, leaving cellulitis around a small ulcer infected with Staphylococcus aureus and Streptococcus pyogenes. The cellulitis responded to oral flucloxacillin. Subsequent multiple small exaggerated insect bite reaction lesions settled with oral prednisolone. Eosinophilic cellulitis (Wells' syndrome) was considered unlikely based on the lack of a morphoea-like resolution phase, histological lack of flame figures and presence of vasculitis; however, the distinction is probably artificial.