Dermatology Online Journal

Eumycetoma
Isaac Brownell MD PhD, Miriam Pomeranz MD, and Linglei Ma MD PhD
Dermatology Online Journal 11 (4): 10

Department of Dermatology, New York University School of Medicine

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Abstract

Eumycetoma is a localized, chronic fungal infection of skin and subcutaneous tissues. It is characterized by tumefaction, abscess formation, draining sinuses, and sclerotia (grains) within the abscesses and fistulae. Treatment of eumycetoma is a challenge. Relapse rates are high even when a combination of surgical and medical approaches is utilized. Here we report a case of eumycetoma due to Exophiala jeanselmei arising on the foot of a man from Trinidad, West Indies.

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A 44-year-old man was referred for evaluation of a mass on his right foot. Approximately 20 years prior, the patient sustained minor trauma to the medial aspect of the right foot while outdoors in Trinidad. Weeks later, a painless mass appeared in the same area and slowly increased in size over years. Multiple, recurrent sinuses that drained serosanguinous fluid developed within the area of tumefaction. Occasionally, minute dark granules could be seen in the sinus drainage. In 1998, the patient received oral itraconazole for 12 months with appreciable thinning of the mass. Clinical resolution was not achieved, and the lesion slowly increased in thickness and expanded to include the plantar surface of the foot after cessation of oral antifungal therapy. In 2003 the patient underwent surgical excision of the medial mass with skin graft closure. Subsequently, intermittent sinus drainage began within the thickened subcutaneous plantar plaque. Recently, the patient has experienced pain on weight bearing. The patient is otherwise healthy and denies the use of medications.

A hyperkeratotic, firm plaque that contained hyperpigmented nodules and multiple, crusted fistulae was present on the medial and plantar surfaces of the right foot. The lesion was adjacent to an 8-cm, oval skin graft recipient site over the medial malleolus. There was no active drainage. Lymphadenopathy was absent.

Figure 1	Figure 2

A complete blood count, comprehensive metabolic panel, hepatic function panel, and erythrocyte sedimentation rate were normal.

Multiple magnetic resonance imaging studies (1996, 1999, 2000, and 2001) of the right foot showed a circumscribed, subcutaneous, soft tissue mass along the medial aspect of the right foot without osseous involvement. The thickness of the mass fluctuated between studies, with thinning immediately after the administration of antifungal therapy. The posterior and plantar margins of the tissue mass showed interval expansion from baseline.

Bacterial, fungal, and acid-fast bacilli cultures from a skin biopsy specimen in 1998 failed to grow organisms. Wound cultures in 2000 also were negative. A potassium hydroxide preparation was positive for hyphal elements in 2001. Tissue from a 2002 biopsy specimen grew Exophiala jeanselmei.

Histopathology reveals a deeply-seated abscess surrounded by an infiltrate of lymphocytes, plasma cells, and fibrosing granulation tissue. Within the abscess, there are several grains of pigmented filamentous fungi arranged radially at the periphery. Gomori's methanamine silver stain highlights the fungal elements.

Comment

Mycetoma is a localized, chronic infection of skin and subcutaneous tissues. It is characterized by tumefaction, abscess formation, draining sinuses, and sclerotia (grains) within the abscesses and fistulae. Mycetoma can be associated with filamentous bacteria (actinomycetoma) or with true fungi (eumycetoma). Worldwide, 60 percent of mycetomas are bacterial and 40 percent are fungal. The causative organisms are found as saprobes in the soils and plants of tropical and subtropical regions [1, 2].

Infection occurs at the site of organism inoculation. This is frequently due to penetrating trauma on the foot. The resulting infection is known also as Madura foot, which is the name of the district of India where it was first described. Most infections are in healthy individuals; however, there are reports of mycetoma in immunocompromised individuals. The clinical course of actinomycetoma and eumycetoma are similar, with painless, slow-growing nodules or plaques that develop draining sinus tracts. Pain and disfigurement can result if the infection spreads to underlying bones. Actinomycetomas will often expand faster than do eumycetomas [1, 2, 3].

Diagnosis of mycetoma is made by examination of sclerotia either directly or histologically. Different grain colors are associated with various infectious organisms. Dark grains, as seen in our patient, are associated with fungal agents, such as the Exophiala jeanselmei that was eventually identified in our patient's mycetoma. Culture of the infectious organism is often useful in directing therapy. With respect to treatment, actinomycetomas tend to respond better than do eumycetomas to medical management. They often resolve with oral antibiotic therapy while eumycetomas are frequently refractory to antifungal drugs and have high relapse rates. Surgical debridement of eumycetomas in conjunction with long-term antifungal therapy is often necessary. Amputation may be a last resort in chronic, progressive, recalcitrant cases of eumycetoma [1, 2, 3].

There are over 30 fungal species that are associated with eumycetoma in humans. The most common one associated with black-grain eumycetoma is Madurella spp. [2]. However, Exophiala jeanselmei has been reported as infrequently responsible for eumycetoma [4, 5]. It is a dematiaceous (pigmented) fungus widely distributed in soil, plants, and decaying wood. As a human pathogen it is known to be associated with eumycetoma, phaeohyphomycosis, and rarely chromoblastomycosis [6]. There are also reports of E. jeanselmei associated with onychomycosis [7], keratitis [8], and nosocomial outbreaks of fungemia [9]. This is the first report of Exophiala jeanselmei eumycetoma from a Caribbean nation.

References

1. Kemper CA. Eumycetoma. Curr Treat Options Infect Dis 2000;2:533

2. Pang KR, et al. Subcutaneous fungal infections. Dermatol Ther 2004;17:523

3. Fahal AH. Mycetoma: a thorn in the flesh. Trans R Soc Trop Med Hyg 2004;98:3

4. Hemashettar BM, et al. Mycetoma due to Exophiala jeanselmei (a case report with description of the fungus). Indian J Pathol Microbiol 1986;29:75

5. Thammayya A, Sanyal M. Exophiala jeanselmei causing mycetoma pedis in India. Sabouraudia 1980;18:91

6. Padhye AA, Warnock DW. Infection may not have been caused by Exophiala jeanselmei. Clin Infect Dis 2000;31:845

7. Boisseau-Garsaud AM, et al. Onychomycosis due to Exophiala jeanselmei. Dermatology 2002;204:150

8. Ben-Simon GJ, et al. More than tears in your eyes (Exophiala jeanselmei keratitis). Cornea 2002;21:230

9. Nucci M, et al. Nosocomial outbreak of Exophiala jeanselmei fungemia associated with contamination of hospital water. Clin Infect Dis 2002;34:1475

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