A 14-year-old boy presented complaining of a nagging ache in both ankles. There was no relevant history and, apart from the radiographs (Fig. 1), a bone survey failed to show any other abnormality. Your diagnosis is?
A centrally placed lucency in the metaphysis adjacent to the growth plate in an adolescent, as seen in both distal tibias (Fig. 1), is characteristic of a Brodie's abscess. However, a similar appearance may be found in: giant cell tumor which should be asymmetrical, aneurysmal bone cyst which should be away from the growth plate and asymmetrical, fibrous dysplasia which should be away from the growth plate, and brown tumors of hyperparathyroidism. Fibrocortical defects should be cortical, not central, and eosinophilic granuloma, although it may mimic most things, would not abut the growth plate.
Benjamin Brodie first described the subacute bone abscess that bears his name in 1832 when he mistakenly amputated the leg of a young man thinking that it was a tumor. He subsequently made the correct diagnosis of a primary subacute pyogenic osteomyelitis.1 Since then, there have been many descriptions and series of Brodie's abscesses23 and, although the case presented has many similarities to the classical appearance, a number of major differences exist. The most obvious difference is that the finding was bilateral. Also, on the left side (Fig. IB), the abscess appears to extend across the growth plate to involve the epiphysis. Although the exact pathogenesis of Brodie's abscess is poorly understood, the lesion is probably most often due to a fit host or a weak pathogen, occurs as a result of a bacteremia, and may be considered as an embolic phenomenon. Hence, the common finding of a Brodie's abscess in the lower limb (90%), at the distal ends of the tibia (70% of tibial lesions), or in the femur (60% of femoral lesions) should not be surprising.4 However, bilateral Brodie's abscess appears to be rare, occurring in less than 1 in a 1,000 cases.4
If Brodie's abscess is considered to be an embolic phenomenon, the situation in the patient presented is obviously analogous to that of a recently described condition called chronic recurrent multifocal osteomyelitis (CRMO). 58 Although this condition was first described under this name in 1972 by Giedion,5 a similar appearance was described in children with meningococcemia in 1921 .9 If the descriptions of the two conditions are compared, they appear to be identical and no point is made by separating them, thus the term CRMO is preferred. Brown and Wilkinson6 described U patients from ages 4?? to 15 years who experienced pain, soft tissue swelling, decreased range of motion, and increased sedimentation rate.6 Radiographically, they all had small lytic metaphyseal lesions often adjacent to the physis predominantly in the distal femurs, clavicle, and vertebral bodies. However, Mortensson et al were able to find 31 children from ages 2 Vi to Wh years with this condition.7 Radiographically, they all showed well demarcated lytic metaphyseal lesions with a pyramidal shape or sinuous border, ie, the authors' description of a Brodie's abscess. There were 89 lesions: 33 in the distal tibia and fibula, 12 in the proximal tibia and fibula, 12 in the foot. 11 in the vertebrae, 9 in the distal radius and ulna, and 12 in other locations. Although the histological diagnosis of chronic osteomyelitis could be made, no bacteria, fungi, or tuberculosis were found in any of the lesions.
Fig. 2: Technetium 99m-MDP bone scan demonstrates increased activity in the right elbow and left femur (A). Permeative pattern, patchy cortical destruction, and periosteal new bone in distal half of the left femur is a typical picture of osteomyelitis (B). Laminated periosteal reaction and permeative destruction is also evident in the proximal right radius (C).
The authors have recently had a similar case. A 2year-old boy had chicken pox and developed a superimposed group A streptococcal infection, which is not an uncommon complication.10 Septic shock and disseminated intravascular coagulation, which are rare but described complications of varicella" and/ or streptococcal sepsis,12 resulted in multi-organ failure and ischemia of his extremities. After several months of intensive treatment, including amputation of both lower legs, the patient was much improved clinically but suffered from persistent fevers. A technetium 99m-MDP bone scan (Fig. 2A) showed intense activity in the distal left femur and around the right elbow. Radiographs of the left femur (Fig. 2B) and proximal right radius (Fig. 2C) showed permeative bone destruction, cortical breakthrough, and laminated periosteal reaction. No organisms were cultured from a biopsy of his left femur, but the fevers subsided with antibiotic treatment.
Previously, the authors came across another child with similar lesions which were, in this case, caused by meningococcal septicemia. This child had been very ill for some time and was now severely mentally retarded. The radiographs (Figs. 3 A and 3B) show characteristic changes of lucencies in the metaphyseal regions, as well as the epiphyses of the long bones which had been slowly progressive over the course of the child's life. There were some cupshaped epiphyses and a curious trabecular pattern had also developed. These are characteristic appearances of multiple septic emboli as seen in this rare condition.13,14
Fig. 3: Lateral view of the left ankle reveals a disordered trabecular pattern in the bones, cystic lucency in the distal tibial metaphyses abutting the growth plate, and destruction of a portion of the distal fibular metaphysis and epiphysis (A). AP view of both knees reveals distal right metaphyseal !licencies abutting the physeal plate, lucencies in both distal femoral epiphyses, and a disordered trabecular pattern in the bones of both knees (B). There is a suggestion of invagination of the midportton of both distal femoral epiphyses into the metaphyses, suggesting central fusion of the physis.
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Section Editor: Terrence Demos, MD