Purpose: Mycetomas are progressive pseudotumours affecting the skin, soft tissue or bone caused by bacterial or fungal infection. Although the foot and ankle are often affected and considered together, mycetoma of the ankle should be considered as a separate nosological entity. The purpose of this work was to study the frequency of primary mycetoma of the ankle and describe the different anatomicoclinical variants and prognostic factors.

Material and methods: Thirty-five cases of primary mycetoma of the ankle were reviewed retrospectively. This series was selected from a total of 141 mycetomas treated between July 1998 and November 2110. There were 22 men and 13 women. The patients were farmers or cattle raisers, mostly belonging to the toucoulour and peulh ethnic groups. Mean duration of the mycetoma was six months (nine months – twenty years). The right ankle was involved in 21 cases and the left in 12, the side was not noted in two cases. A fungal cause was identified in 25 cases [black grain = 24 (Madurella mycetomatis = 8, Leptospheria senegalensis = 6, unidentified = 11) and white grain = 1 (Pseudoallescheria boydii)]. Actinomycosal infection was identified in six cases [red grain = 2 (Actinomadura pelletieri), white grain = 4 (Actinomadura madurae) and yellow grain = 1 (Streptomyces somaliensis)]. The causal agent was unidentified in four cases. Sixteen patients underwent surgical treatment, surgical treatments were scheduled for four patients, and four were treated medically.

Results: Primary mycetoma affected the ankle in 16.3% of the cases. The presence of a benign encapsulatd (37.5%) often uniretromalleolar or biretromalleolar nodule was characteristic of the fungal form. A diffuse polyfistulated (41.6%) and premalleolar form which eventually covered the entire ankle was also noted. Secondary bone infection led to osteitis and or osteoarthrtis in 54.1% of the cases. Mycetomic osteitis required amputation in 5 patients (20.8%). We noted one case of recurrence among our direct admissions and five cases among referrals.

Conclusion: Mycetoma of the ankle should be distinguished from mycetoma of the foot. The benign encapuslated fungal form is situated behind the malleolus and can be distinguished from the diffuse polyfistulated osteophilic actinomycosic or fungal form that covers the entire ankle.