Erythema Nodosum

Question 1

Define erythema nodosum.

Answer 1

Erythema nodosum (EN) is a common cutaneous hypersensitivity reaction consisting of erythematous, tender nodules most commonly located over the shins, but also reported over the thighs, upper extremities, calves, buttocks, and face.

Question 2

Explain the aetiology/risk factors of erythema nodosum.

Answer 2

Streptococcal infection
Sarcoidosis
Tuberculosis
Coccidioidomycosis
Histoplasmosis
Blastomycosis
Behcet’s disease
Oral contraceptives
Leprosy

Question 3

Summarise the epidemiology of erythema nodosum.

Answer 3

Erythema nodosum occurs more frequently in Europe than in North America, although the exact incidence is not known. It can occur at any age but peaks between 20 and 30 years.

Question 4

Recognise the presenting symptoms of erythema nodosum. Recognise the signs of erythema nodosum on physical examination.

Answer 4

Nodules on shins
Uveitis, red eyes, retinal nodules, or candle-wax drippings
Nodules on other skin areas
Joint pains
Fever

Question 5

Identify appropriate investigations for erythema nodosum and interpret the results.

Answer 5

FBC
Antistreptolysin-O titre
CXR
Purified protein derivative skin testing