An eight-year-old boy presented with a six-month history of pain, swelling,
and multiple discharging sinuses over the heel of the left foot. There was no
history of trauma or skin puncture, but there had been intermittent discharge
of black-colored granules from the sinuses along with an associated occasional
low-grade fever. There were no systemic or constitutional symptoms otherwise.
He had received treatment in the form of local dressings and broad-spectrum
antibiotics from his primary care physician, but these treatments had had no
appreciable effect.
Clinical examination of the left heel revealed discharging sinuses with
black, soft, irregular, sprouting granules and surrounding granulation tissue
(Fig. 1). Local warmth and
chronic skin changes were present. The calcaneus was thickened and tender to
palpation. Movement of the ankle and the subtalar joints was painfully
restricted. There was no distal neurovascular deficit. The superficial
inguinal lymph nodes were enlarged, firm in consistency, and nontender. The
remainder of the physical examination, including that of the chest, was
normal.
A radiograph of the left heel (Fig.
2) showed extensive loculated lytic areas of bone destruction
within the body of the calcaneus, with a typical honeycomb appearance.
Magnetic resonance imaging of the left foot revealed diffuse alteration in the
signal intensity of the calcaneal marrow, with a hypointense signal on
T1-weighted images and a hyperintense signal on T2-weighted images, indicating
osseous erosion. Multiple foci appeared hypointense on all pulse sequences and
were seen to be interspersed within the calcaneus
(Fig. 3). A hemogram revealed a
modestly increased erythrocyte sedimentation rate and an absolute lymphocyte
count of 1500/mm3 (1.5 × 109/L). Total T cells (as
measured by anti-CD3 surface markers) and estimations of the CD4+
helper-cell populations and CD8+ suppressor-cytotoxic populations
were within the normal range. The patient was HIV-negative. The chest
radiograph was normal.
Granules were collected with use of aseptic measures and were inoculated on
blood agar, Sabouraud dextrose agar with chloramphenicol (SDA+C), and
brain-heart infusion (BHIA) medium with antibiotics. Growth was achieved on
the SDA+C media after twenty-eight days. The colonies were olive-black and
velvety in appearance. When viewed under the microscope, colony samples that
were stained with lactophenol cotton blue (LPCB) wet mount preparation were
seen to have pale-brown, branched, septate hyphae
(Fig. 4). The periodic
acid-Schiff-positive hyphae gave rise to simple conidiophores from both the
lateral and terminal positions. The conidiogenesis was compatible with the
microscopic morphology of Exophiala jeanselmei.
Following the diagnosis of Exophiala jeanselmei infection, the
patient was managed with ketoconazole (200 mg per day, administered orally in
two divided doses). After two weeks of ketoconazole therapy, a radical
surgical débridement of the calcaneus was done through an L-shaped
lateral incision. All necrotic bone and granulation tissue were removed to
bleeding bone. No bone graft was used. The sinuses were curetted, and the
wound was partially closed. The postoperative period was uneventful. The child
showed recovery both clinically and radiographically after a total of twelve
weeks of ketoconazole therapy. At the time of the ten-month follow-up, there
was no evidence of recurrent infection or subtalar joint collapse
(Fig. 5), and the child was
walking bearing full weight.
Mycetomas are localized, slowly progressive, chronic granulomatous
infections caused by fungi (eumycotic mycetoma) or by certain actinomycetes.
It is important to distinguish between eumycotic mycetoma and actinomycotic
mycetoma for proper management of the infection. This infection is
characterized by a prolonged incubation period, a slow and unremarkable
clinical course, and multiple causal
agents3.
Exophiala jeanselmei is an uncommon cause of black-grain eumycotic
mycetoma. The common causative agents of eumycotic mycetoma reported by
various authors are Madurella mycetomatis, Madurella grisea,
Acremonium species, Aspergillus species, and Fusarium
species4,5.
Isolation of Exophiala jeanselmei from a mycetoma is reported very
rarely in the world
literature6, and we
were not able to find a previously reported case of isolated calcaneal
osteomyelitis due to Exophiala jeanselmei infection.
Fungal osseous lesions in immunocompromised hosts are reported
frequently1,2,
but fungal osteomyelitis in an immunocompetent host is rare. Environmental
factors are known to predispose otherwise healthy adults and children to
fungal
infections7.
The different modalities of treatment of fungal osteomyelitis include
chemotherapy with ketoconazole or itraconazole. Ketoconazole, the drug of
choice, is cost-effective but has hepatic and endocrinologic side
effects8. In cases
of failure of the antifungal agent, radical treatment by surgical
débridement or amputation may be required.
This case report highlights the importance of awareness of mycetoma
pathology even in an immunocompetent host. All forms of chronic osteomyelitis
with draining sinuses in uncommon anatomic locations should be suspected as
fungal infections, particularly if there is little or no response to bacterial
chemotherapy. With combined radical débridement and effective
chemotherapy, a good final clinical result is possible. ?