Erythema Nodosum on Shins of a 16-Year-Old Girl

A 16-year-old girl had had tender, erythematous, nodular, shiny lesions on the extensor aspect of both shins for 2 weeks. There were no ulcerations or adenopathy. She denied fever, cough, sore throat, pruritus, and GI symptoms. Aside from oral contraceptives, she was not taking any medications.

Results of a throat culture and pregnancy test were negative. Complete blood cell (CBC) count and a chest radiograph were normal.

Muhammad Waseem, MD, of Bronx, NY, made the diagnosis of erythema nodosum based on the clinical appearance of the lesions, which are usually bilateral, extremely tender nodules that develop symmetrically on the shins. This inflammatory exanthema of unknown cause is commonly associated with use of certain medications-especially oral contraceptives. A thorough history and physical examination with laboratory evaluation (including CBC count), throat culture, and chest film must be performed to exclude an underlying cause, such as streptococcal infection, tuberculosis, sarcoidosis, fungal infection, inflammatory bowel disease, or leukemia. Streptococcal infection is the most common cause of erythema nodosum in children, and it is one of the most common causes in adults, along with sarcoidosis.

The lesions of erythema nodosum are generally self-limited. Most resolve spontaneously within a few weeks. The prognosis is excellent. Repeated episodes may occur during pregnancy and with the use of oral contraceptives.

There is no known therapy. Anti-inflammatory agents can be used to relieve symptoms in patients who do not have underlying infection or drug allergy.