A 39-year-old lieutenant colonel stationed in Saudi Arabia with arthritis, fevers, and rash

Military Medicine, Jan 2002 by Gilliland, William R

3. Erythema nodosum has been associated with all the following EXCEPT.

a. Blastomycosis

b. Streptococcal infection

c. Behcet's disease

d. Vitamin B12 deficiency

e. Sarcoidosis

Erythema nodosum is characterized by painful erythematous nodules on the anterior surface of both legs.

They frequently are numerous and may become confluent, leading to diagnostic confusion as it did in this patient. The nodules may evolve into bruise-like lesions. Regardless of its appearance, erythema nodosum typically resolves over a 2- to 8-week period without scarring or ulceration. Current hypotheses on the etiology of erythema nodosum suggest that the lesions represent a delayed hypersensitivity reaction to antigens associated with various infectious agents, drugs, and other diseases. The most common causes of erythema nodosum include idiopathic, infections, drugs, sarcoidosis, and other conditions (Fig. 2).2 Of the infectious etiologies, non-streptococcal upper respiratory infections, group A Streptococcus, tuberculosis, Escherichia coli, and Brucella are the most common. Several fungi, including blastomycosis, have also been associated with erythema nodosum. Antibiotics such as ampicillin, erythromycin, and other agents may also be associated with this condition. Other recognized syndromes associated with erythema nodosum include Sweet's syndrome, Behget's syndrome, malignancy, and inflammatory bowel disease. B 12 deficiency has not been associated with erythema nodosum.

By day 7 of the patient's hospitalization, his ankle pain and swelling improved markedly but the erythema nodosum lesions continued to migrate proximally on his legs. A highresolution computed tomographic scan of his lungs revealed right hilar adenopathy with the largest lymph node measuring 1.1 cm. A transbronchial biopsy was nondiagnostic. The pulmonary diffusing capacity for carbon monoxide (DLCO) was moderately reduced (69% of predicted).

Because the patient continued to have constitutional symptoms and because of the concern of the providers for possible malignancy, a repeat high-resolution computed tomographic scan of his lungs was performed. This revealed interval enlargement of his right hilar adenopathy with the largest lymph node now measuring 1.4 cm. To reduce any diagnostic uncertainty, a mediastinoscopy was performed and multiple lymph node biopsies were taken.

4. Conditions causing hilar adenopathy and erythema nodosum include all of the following EXCEPT.

a. Sarcoidosis

b. Cat scratch disease

c. Histoplasmosis

d. Hodgkin's disease

e. Tuberculosis

The differential diagnosis of hilar adenopathy associated with erythema nodosum is quite limited and includes sarcoidosis, tuberculosis, coccidioidomycosis, histoplasmosis, Hodgkin's disease, blastomycosis, chlamydial infection, and yersiniosis. Although cat scratch disease, caused by Bartonella henselae, is frequently associated with lymphadenopathy, the location of the adenopathy depends on the site of inoculation. Hilar adenopathy would therefore be rare. Cat scratch disease has not been associated with erythema nodosum.