Radiological Case of the Month FREE

A 14-YEAR-OLD GIRL was referred for evaluation of a fever of unknown origin. She was in good health until 2 months previously, when she abruptly developed an elevated temperature and back pain. A urine culture was sterile. She had an elevated white blood cell count and a Westergren erythrocyte sedimentation rate of 116 mm/h. A chest radiograph and abdominal ultrasound were normal. Sinus radiographs indicated sinusitis. She was treated with azithromycin without improvement. A radionuclide bone scan demonstrated increased tracer uptake in the calvarium, left ninth rib posteriorly, and both knees. Results from radiographs of the skull and knees were normal. Serum antinuclear antibodies were positive with a level of 1:80. Several blood and urine cultures were sterile. Results of a serologic study for Epstein-Barr virus suggested a distant infection. A cytomegalovirus serologic study was negative.

The patient had a temperature of more than 40°C daily and had migratory arthralgias, occasional frontal headaches, and intermittent nausea and anorexia. She had lost 5.85 kg during this illness. The patient lived in a metropolitan area and had not traveled recently. The family had 2 cats and the patient also reported exposure to a hamster, dogs, and a lizard. She reported multiple insect bites in the preceding several months. She denied consumption of unpasteurized milk. The family history was unremarkable.

On physical examination, the girl was pale and appeared ill. Her temperature was 38.3°C and her blood pressure was 130/75 mm Hg. The oropharynx was slightly erythematous with no exudates. The first and second heart sounds were normal. A third heart sound and intermittent gallop were audible with no cardiac murmurs noted. An epigastric bruit was present. The results from the remainder of the physical examination were normal.

The total leukocyte count was 10.9 × 10⁹L, with a normal differential. Hematocrit was 0.26 and platelet count was 725 × 10⁹/L. The Westergren erythrocyte sedimentation rate was 98 mm/h. The C-reactive protein level was elevated to 149 g/L, and the serum electrolyte, blood urea nitrogen, creatinine, albumin, uric acid, and lactic dehydrogenase levels were normal. Serum alanine aminotransferase level was elevated at 69 U/L (normal, 4-46 U/L), but aspartate aminotransferase and bilirubin levels were normal. A urinalysis showed trace hemoglobin. Blood and urine cultures were sterile and stool cultures isolated only normal enteric flora. Serologic testing for coccidioidomycosis, toxoplasmosis, syphilis, hepatitis A virus, hepatitis B virus, and human immunodeficiency virus was negative. Purified protein derivative skin testing was negative, and Candida and tetanus antigen tests were positive.

A chest radiograph (Figure 1) was performed. Results of an echocardiogram showed mild aortic regurgitation. Magnetic resonance imaging of the thorax (Figure 2, left and right) followed.