Mycetoma.

A 46-year-old male, a grocer by occupation was referred from the orthopedics department for swelling of his right leg with discharge from overlying skin since 18 months. He was a known case of chronic osteomyelitis since 7 years. Cutaneous examination revealed diffuse swelling of right thigh and leg along with effusion of right knee joint. Also, there were multiple sinuses on right thigh and on upper one-third of right leg. Two sinuses were found discharging serosanguinous fluid along with black granules [Figure 1]. Multiple healed atrophic scars were noticed on right thigh. KOH preparation of the crushed granules showed septate branching phaeoid hyphae [Figure 2]. Culture on Sabouraud's dextrose agar was negative for maduramycosis. Radiograph of the right leg showed circumscribed osteolytic lesion in the metaphyseal region of right tibia [Figure 3]. Magnetic resonance imaging (MRI) of right leg showed well-defined, ovoid, mixed intensity lesion in the metaphyseal region of right upper one-third of tibia. The 'dot-in-circle' sign was visualized [Figure 4]. Lesional biopsy was noncontributory. Characteristic clinical morphology, microscopy of the granules, radiography, and MRI assisted in establishing the diagnosis of mycetoma.

Figure 1

Multiple sinuses on right thigh and upper one-third of right leg. Two sinuses show discharging serosanguinous fluid along with black granules

Figure 2

KOH mount of the crushed granules showing septate branching phaeoid hyphae

Figure 3

Radiograph of right leg showing circumscribed osteolytic lesion in the metaphysical region of right tibia

Figure 4

MRI of right leg showing well-defined ovoid mixed intensity lesion in the metaphyseal region of right upper one-third tibia with the 'dot-in-circle' sign (arrow)

Mycetoma is a chronic granulomatous infection of the skin and subcutaneous tissues characterized by induration, abscess formation with draining sinuses. It is caused by both fungi (eumycetoma) and filamentous bacteria (actinomycetoma). It derives its name from Madurai, the place where it was first reported. The clinical features are the same irrespective of the causative agent.[1] Madurella mycetomatosis is one of the commonest causes of eumycetoma[2] and it is common among males who perform more outdoor activity. Usually follows injury such as a thorn prick or an injury resulting in ulceration. Similarly, mycetoma followed vehicular injury in our case. The foot is a common site of involvement followed by and extremities and perineum.[3] Involvement of the upper part of the leg in our case is in concert with the common sites of involvement. Confirmation of the diagnosis is by demonstration of the fungus and speciation by culture on Sabouraud's dextrose agar.[4] However, only fungal elements could be demonstrated in our case but failed to culture the fungus on Sabouraud's dextrose agar. The surface of the colony is heaped up, and radially folded with a glabrous to wooly texture. Its color varies from white to yellow-brown to dark gray or olive brown, whereas the reverse shows brown pigment. The causative fungus could not be established in our case as it could not be cultured. Nonetheless, black granules were found in the discharge overlying the sinuses, which is a characteristic clinical feature of eumycetoma. Bone involvement is a major complication in maduramycosis resulting in osteolytic lesions seen on radiography.[5] The upper end of tibia showed osteolytic lesions in our case. The recently described dot-in-circle sign on magnetic resonance imaging (MRI) is highly specific of maduramycosis.[6] Treatment of eumycetoma consists of antifungal drugs combined with surgery. Antifungal drugs such as itraconazole, posaconazole, ketoconazole, and terbinafine long are required to be administered for a long duration.

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