Diagnosis: Insect bite reaction / Cellulitis

Comments: A 13 year old girl awoke 5 days earlier with 2 small red bumps in the left popliteas fossa. The papules became painful and expanded beyond the pen marks drawn by the patient. (Note the faint lines.) There was a large area of faint erythema, extending beyond the 2 dark red indurated plaques, that was outlined by her doctor in dark black ink. Although it was difficult to distinguish a possible toxic reaction from the bites from secondary infection, she was treated with an oral antistaphylococcal antibiotic, and the lesions cleared over the subsequent week.

Category: reactive erythema / lumps & bumps (plaques, nodules, tumors)
Morphology: ulcerated (erosion / ulcer) / papulosquamous (bump, scale) Organization: grouped, clustered Pattern: asymmetric Color: red
Body Site: Age: 13 years Gender: female Image Year: 2002
Contributor: Edwin King, MD First Published: May 23, 2002
Description: two 1.5 cm indurated red plaques with necrotic crusted centers and faint surrounding erythema.

Image & content, Copyright Dermatlas, Johns Hopkins University.