Diagnosis: Erythema nodosum
Description: Sudden tender, erythematous, hot nodule.
Morphology: Nodule
Site: Leg
Sex: F
Age: 22
Type: Clinical
Submitted By: Mehravaran Mehrdad
Differential DiagnosisHistory: Erythema Nodosum(EN) is characterized by the eruption of erythematous nodules and plaques located predominantly over the extensor aspects of the lower extremities. This disorder usually exhibits an acute course, with spontaneous regression, without ulceration, scarring, or atrophy. Clinically EN is the most common type of panniculitis. EN can occur at any age, but most cases appear between the second and fourth decades of life, with the peak incidence between 20 and 30 years of age. In general, EN is seen in younger patients than nodular vasculitis. EN is three to six times more frequent in women than in men; however, the sex incidence before puberty is approximately equal. In children, EN occurs commonly in association with TB and streptoccocal infections, and the prevalence of these diseases is the same in both sexes. The typical eruption of EN is quite characteristic. The lesions consists of symetrical, tender, erythematous, hot, and raised nodules and plaques usually located on the shins, ankles, and knees. Usually, the lesions are bilaterally distributed. More extensive cases may involve the thighs, extensor aspects of the arms, neck, and in rare instances, the face. The size of the lesions range from 1-15 cm and the number from 1-10, but sometimes 50 or more nodules are present at the same time. Ulceration is never seen and the nodules heal without atrophy or scarring, two clinical features that distinguish EN from nodular vasculitis. The eruption lasts 3-6 weeks, but persistance beyond this time is not unusual. Recurences of the lesions may also appear, and chronic and persistent forms of EN occur is some patients. The most common causes of erythema nodosum are infections of the upper respiratory tract, such as by Mycobacterium tuberculosis and Yersinia, drugs, including oral contraceptives, sarcoidosis, and inflammatory diseases of the gastrointestinal tract, such as Crohn's disease and ulcerative colitis. A 22-year-old active university student female with chief complaint of sudden onset of a tender, erythematous, hot, raised nodule on the peritibial region which started 4 weeks before. General condition rule out fever, malaise, fatigue, arthralgia, headache, abdominal pain, vomiting, cough, or diarrhea. Labratory tests such as CXR , Mantoux Test, ASO titer all were in normal range. The only etiologic cause for appearance of such lesion, was Oral Contraceptive agent. Meanwhile patient is under bed rest, oral conteraceptive were discontinued, NSAID agent and potent local steroid were offered.