Mycetoma
Mycetoma, often referred to as "fungal tumor," is a chronic granulomatous disease characterized by localized infections caused by fungi or actinomycete bacteria. There are two primary forms of mycetoma: pulmonary mycetoma, which affects the respiratory tract, and subcutaneous mycetoma, commonly known as Madura foot, which can manifest on the skin or beneath it, particularly in the feet, hands, or back. This infection typically arises following trauma that allows microorganisms to enter the skin.
Pulmonary mycetoma is commonly associated with pre-existing lung conditions, while subcutaneous mycetoma is prevalent in tropical and subtropical regions, especially in Africa and South Asia. Symptoms can vary; pulmonary cases may be asymptomatic or present with cough and chest pain, whereas subcutaneous cases develop slowly, leading to significant tissue damage over time. Diagnosis often occurs incidentally through imaging or after the infection has progressed, with identification confirmed through culture of the involved tissue. Treatment approaches depend on the form of mycetoma, ranging from antifungal medications to surgical intervention, highlighting the need for timely medical attention to prevent severe complications.
Mycetoma
- ANATOMY OR SYSTEM AFFECTED: Respiratory system, skin
- ALSO KNOWN AS: Actinomycetoma, aspergilloma, eumycetoma, Madura foot
Definition
A mycetoma is a mass or abscess caused by fungi or actinomycete bacteria. The mass often resembles a tumor, hence the form of the name meaning “fungal tumor.” There are two distinct mycetoma diseases: One occurs in the respiratory tract (as an aspergilloma) and the other occurs on or in the skin or subcutaneously in the foot, hand, or back (as Madura foot).
Causes
Pulmonary mycetoma is most often caused by species of the fungus Aspergillus (and is often called an aspergilloma), but other respiratory fungal pathogens can also form pulmonary mycetomas. Pulmonary mycetomas often form in preexisting lung cavities.
Subcutaneous mycetomas can be caused by both fungi (eumycetoma) and filamentous actinomycete bacteria (actinomycetoma). Fungi of the genera Madurella and Scedosporium are commonly implicated, but other fungi are also known to cause mycetomas. Actinomycetes, although they are bacteria, not fungi, resemble fungi in both microbiological and clinical ways. Actinomadura sp., Streptomyces sp., and Nocardia sp. are the most commonly implicated actinomycetes in subcutaneous mycetomas. Cutaneous and subcutaneous mycetomas are often acquired when organisms enter the skin after local trauma.
Risk Factors
Pulmonary mycetomas have a predisposition to occur in preexisting lung cavities. These cavities are frequently caused by tuberculosis, coccidioidomycosis, histoplasmosis, lung neoplasms, sarcoidosis, bronchiectasis, and lung abscesses. Mycetomas may occur in up to 15 percent of persons with cavitating lung diseases caused by tuberculosis.
Cutaneous mycetoma occurs mainly in tropical or subtropical areas, especially in Africa and South Asia. Madura foot is named after the region of India where this form of the disease was first described medically. A strong risk factor is outdoor work, especially in underdeveloped countries.
Symptoms
For pulmonary mycetoma, most persons are asymptomatic. When symptoms occur, the most common are cough, chest pain, and hemoptysis.
Subcutaneous mycetomas progress slowly over months or years, with little or no initial symptoms. After years, the affected area can have extensive swelling, induration, skin rupture, and sinus formation. The infection can destroy nearby muscle, tendon, bone, and other tissue, eventually causing severe deformity and tissue destruction.
Screening and Diagnosis
Pulmonary mycetoma is most often diagnosed after lung imaging, often when looking for other conditions, such as tuberculosis or lung neoplasia. Subcutaneous mycetoma often goes undiagnosed for many years until the mycetoma erupts. Exudates of the sinus tracts have grains of the causative agent. The cause is usually confirmed by a culture of exudates.
Treatment and Therapy
Because the nature of pulmonary mycetoma is highly variable, most infected persons are kept under observation without therapy. However, if persons develop hemoptysis (coughing up blood), then antifungal therapy is usually initiated. The primary antifungal drugs used are itraconazole, voriconazole, and amphotericin B. In severe cases, surgical resection of the affected lung or arterial embolization may be necessary.
For subcutaneous mycetoma, treatment includes antimicrobials specific to the causative organism or organisms, surgical debridement, and, sometimes, amputation. Bacterial secondary infections may lead to sepsis, and if untreated, may result in death.
Bibliography
Ameen, M. “Managing Mycetomas.” Tropical Doctor 30 (2009): 66-68.
Bustamante, B., and P. E. Campos. “Eumycetoma.” In Clinical Mycology, edited by William E. Dismukes, Peter G. Pappas, and Jack D. Sobel. New York: Oxford University Press, 2003.
"Clinical Overview of Mycetoma." Centers for Disease Control and Prevention (CDC), 24 Apr. 2024, www.cdc.gov/mycetoma/hcp/clinical-overview/index.html. Accessed 4 Feb. 2025.
Riscili, B. P., and K. L. Wood. “Noninvasive Pulmonary Aspergillus Infections.” Clinics in Chest Medicine 30 (2009): 315-335.