Brodie’s abscess associated with soft tissue swelling in an athlete in Abidjan (Ivory Coast)

Brodie’s abscess is a subacute form of osteomyelitis, presenting as a collection of pus on the bone [1]. The onset is often insidious with clinical signs and deceptive imaging that may mimic a bone tumor [2]. Publications concerning Brodie’s abscess come mainly from developed countries. There are very few publications from Africa [1]. We report a rare case of the association of a Brodie’s abscess with a swelling of the soft tissues in a sportsman in Abidjan (Ivory Coast).


Introduction
Brodie's abscess is a subacute form of osteomyelitis, presenting as a collection of pus on the bone [1]. The onset is often insidious with clinical signs and deceptive imaging that may mimic a bone tumor [2]. Publications concerning Brodie's abscess come mainly from developed countries. There are very few publications from Africa [1]. We report a rare case of the association of a Brodie's abscess with a swelling of the soft tissues in a sportsman in Abidjan (Ivory Coast).

Report case
30-year-old sports patient with no particular history who consulted in November 2018 for the management of right knee pain associated with swelling of the distal third of the thigh. The patient had presented two months prior to a right knee trauma during a football match. He did not seek medical attention and slight increase in SV and CRP without hyperleukocytosis. The standard radiographic workup, followed by CT scan, revealed a lacunar metaphyseal image of the distal femur delimited by a thick, sharply contoured osteocondensation (Figures 2,3). This radiological aspect led us to make the diagnosis of either a bone tumour or a Brodie's abscess. Surgery was therefore performed. The approach was centered on the swelling on the inner side of the distal third of the thigh. We found approximately 300cc of pus extending from the soft tissue to the bone gap.
After removal of the pus and washing with saline, we proceeded to curettage and excision of the osteitis (Figure 4). Samples were taken for bacteriological and pathological examination.
Suturing of the incision was done on a suction drain.
Post-operative antibiotic therapy was given with ceftriaxone 2g intravenously per day. In view of the result of the bacteriological examination which isolated a staphylococcus aureus sensitive to this antibiotic, we continued the antibiotic therapy until D 10. The anatomopathological examination ruled out any tumour process. The postoperative evolution was satisfactory with a drying of the suppuration. At the patient's discharge, the antibiotic therapy was relayed per os with cefi xime. Healing was achieved and the patient was able to resume almost all his activities after 60days.

Discussion
This observation was of a young adult athlete with a Brodie's abscess associated with soft tissue swelling, a condition described as rare [3]. In this case, the falsely incriminated trauma led to delayed diagnosis. The radiological diagnosis of the distal metaphyseal osteolytic lesion of the femur was made in our context with standard radiography and CT scan. We were unable to perform magnetic resonance imaging (MRI) because this examination was expensive for our patient. MRI is the diagnostic test of choice in this case, highlighting the abscess as a circumscribed image appearing as a hyposignal image in T1 and a hypersignal image in T2 [4]. Brodie's abscess often poses a diagnostic problem because the clinical and radiological signs may mimic a bone tumour or other bone pathology (ostoid osteoma, osteoblastoma, eosinophilic granuloma, tuberculosis, chondrosarcoma, etc.) that warrants further investigation [2,5,6]. Management must be multidisciplinary, involving the surgeon, radiologist, infectiologist and pathologist [2]. The treatment, as was the case in our patient, is surgical (drainage of pus and bone excision) combined with antibiotic therapy [1]. Staphylococcus aureus was isolated from our patient. This germ is most often found in the literature [1]. The low number of African publications on the subject should not lead us to underestimate the prevalence of this form of osteomyelitis [7] among the large number of chronic osteomyelitis in sub-Saharan Africa [8].

Conclusion
Brodie's abscess, which is subacute osteomyelitis, can be a diagnostic problem with bone tumours. The evolution is favourable under surgical treatment combined with antibiotic therapy.