Case 1: A four-month-old boy with bilateral arm swelling

Abstract

A previously well, four-month-old boy developed tender swelling of both forearms of one months’ duration associated with irritability and moderate fever. An x-ray of the left forearm, performed at a local hospital, revealed a periosteal reaction over the ulna but no fracture line. With a clinical suspicion of osteomyelitis, he was prescribed a course of intravenous antimicrobials. His fever subsided but the swelling and irritability persisted, which prompted the parents to seek a second opinion from our institute. On admission, he was healthy and alert but persistently irritable and was experiencing tenderness over both forearms. A uniform, diffuse, nonfluctuant, immobile, bony thickening of the ulna was palpable at the diaphyses bilaterally (Figure 1A). The overlying skin, and the wrist and elbow joints were normal. No swelling or lymphadenopathy was palpable at any other sites. A repeat x-ray of the left forearm showed an increased periosteal reaction over the left ulna (Figure 1B). An x-ray of the right forearm revealed a similar periosteal reaction along the ulnar shaft and a minimal periosteal reaction along the midradial shaft but no fracture was observed (Figure 1C). Other laboratory investigations found a hemoglobin level of 9.9 g/L, a total leukocyte count of 16.7×109/L (neutrophil 48%, lymphocytes 45%), an erythrocyte sedimentation rate of 40 mm/h, a serum calcium level of 2.18 mmol/L, a phosphorus level of 1.58 mmol/L and an alkaline phosphatase level of 258 IU/L (normal <470 IU/L). Blood and urine cultures were sterile. The Venereal Disease Research Laboratory test was negative in both the mother and child. A technetium-99m-labelled, methyl-diphosphonate bone scan revealed evidence of symmetrically increased osteoblastic activity in the maxilla, mandible, mastoid and bilateral forearm bones. Figure 1) A Clinical photograph of the right forearm showing a uniform, diffuse, nonfluctuant, immobile, bony thickening of the ulna palpable at the diaphyses. B X-ray of the left forearm showing an increased periosteal reaction over the left ulna. C Radiograph ...