Image Quiz
Swelling and Pain in the Knee of a Thirty-Month-Old Child1
A thirty-month-old child complained of pain in the right thigh and knee. Because coughing and sneezing were also observed, a pediatrician diagnosed a common cold and prescribed a nonsteroidal anti-inflammatory drug. On the next day, the child was examined by an orthopaedic surgeon because of the right thigh and knee pain. The right knee was not swollen or warm, and a radiograph showed normal findings. Two weeks later, the patient was examined by us. By then, the right knee was swollen and tender, although an anteroposterior radiograph of the knee did not show any abnormality. A T2-weighted magnetic resonance image of the knee showed low signal intensity only in the center of ossification in the proximal epiphysis of the right tibia (Figs. 1-A and 1-B).
Fig. 1-A |
Fig. 1-B |
Figs. 1-A and 1-B T2-weighted magnetic resonance images made following the onset of knee pain.
Fig. 1-A The proximal epiphysis of the right tibia has low signal intensity, whereas no changes are seen in the proximal growth plate or metaphysis.
Fig. 1-B High signal intensity is seen in the left tibia as well as in the distal epiphysis of the left femur.
For larger view, click on image |
The patient had been vaccinated with BCG (bacille Calmette and Guerin) at eight months of age. The tuberculin skin test was positive, which is normal after the vaccination. There was no family history of tuberculosis.
Serum studies included a normal leukocyte count, a slightly elevated C-reactive protein level (0.73 mg/dL [7.3 mg/L]), and an erythrocyte sedimentation rate of 47 mm/h. As a result, a diagnosis of bacterial infection of the proximal part of the tibia was made.
An antibiotic agent (cefroxadine, 420 mg/day) was administered for six weeks with a subsequent decrease in pain, and all blood-test results improved to within the normal range. Three weeks after discontinuation of the antibiotic, the knee became swollen again, and there was local heat to palpation. Curettage and débridement of the proximal metaphysis of the tibia was done to drain the pus and obtain tissue for biopsy. Histologic examination of granulation tissue from the cavity of the proximal part of the tibia revealed Langerhans giant cells, lymphocytes, and epithelioid cell proliferation.
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