Mycetoma

Sample for mycetoma

1. Get a sample from the lesion.
2. Can take a biopsy of the lesion.

Definition of Mycetoma

• Mycetoma literally means fungal growth or maduromycosis of the foot.
• Mycetoma term refers to severe, deeply chronic, locally progressive, destructive, suppurative, and granulomatous disease.
  • It begins in the subcutaneous tissue, usually of the hand and foot.
  • This involves subcutaneous tissue, fascia, and bone.
  • It is characterized by tumefaction, draining sinuses, and the presence of granules.

Pathology of Mycetoma

1. Two types of microorganisms cause Mycetoma:

2. Bacteria:

   1. These are aerobic actinomycetes, which cause Mycetoma called Actinomycetoma in more than 50% of cases.
   2. The organism in this group are:
      1. Nocardia brasiliensis.
      2. Actinomadura pelletieri.
      3. Actinomadura madurae.
      4. Streptomyces somaliensis.
   3. Actinomyces are:
      1. Actinomyces israelli. It produces actinomycosis.
         1. This chronic internal abscess formation will develop the sinus tract to the skin.
         2. There is purulent exudate containing yellow granules called sulfur granules.
         3. These sulfur granules are masses of actinomycetes.
      2. Actinomyces bovis.

3. Fungal:

   1. Fungal infection causes in the other 50% of the cases.
   2. This is called Eumycetoma, also known as maduromycosis, and is caused by a true fungus.
      1. There are at least 23 types of filamentous fungi that cause Mycetoma. An important one is:
         1. Pseudallescheria boydii (There are yellow granules).
         2. Madurella mycetomatis (There are big black granules).
         3. Medurella grisea.

Presentation of mycetoma:

1. Mostly there is the involvement of the feet and less common hands and other sites.
2. This chronic, suppurative, granulomatous inflammation can involve subcutaneous tissue, fascia, and bone.
3. The etiological agents enter the body through the foot from the soil, possibly due to trauma.
   1. When there is the involvement of the foot, where it is swollen and discolored, numerous draining sinuses form.
   2. This disease is characterized by tumor formation and draining of the abscess.
4. There is the presence of granules or grains in the pus.
   1. Depending upon the causative agents, these granules have different colors, white, black, yellow, and brown.

5. Mycotic mycetoma is more common in men than in women.
6. Mycotic mycetoma is usually due to an injury to the foot.

Pathogenesis of mycetoma due to fungi:

1. When fungi are implanted in the subcutaneous tissue following the trauma.
2. There is a destructive granulomatous lesion that drains through multiple sites.
3. There is local spread but no dissemination.
4. The most common site is the foot, and this infection is called the Medura foot.
5. Causative agent:
   1. Important fungi are filamentous, including:
      1. Medurella mycetomatis.
      2. Medurella grisea.
      3. Phialophora verrucosa.
6. Pathogenesis of fungal Myecetoma:
   1. First, fungi are implanted into the tissue after trauma, which may be splinter.
   2. It produces destructive granulomatous inflammation.
   3. Later on, this lesion drains through multiple sinus tracts.
   4. There is local spread but no widespread dissemination.
   5. This is common in barefoot people.

Laboratory Diagnosis of mycetoma:

1. Collect the granules from the lesion.
   1. Then wash the granules with the saline, crush it, and spread it on the slide.
2. Also, take the culture of the material. Culture is done on the Sabouraud’s medium for fungus.
3. Prepared slides are stained with Gram’s stain :
   1. The filaments are less than or equal to 1.0 micrometer in diameter; these are diagnostic of aerobic actinomycetes and called actinomycetoma.
   2. If the filaments are 2 to 5 micrometers and hyphal in shape, is diagnostic of fungal infection is called eumycetoma.
4. These granules can also be seen in KOH 10% solution.

Treatment of mycetoma:

1. The prognosis of Eumycetoma is poor.
   1. These patients undergo surgical debridement, oral Itraconazole 200 mg twice a day for a prolonged period of time, and response is only 70%.
   2. These patients may be given combination therapy.
2. Mostly these are treated by surgery.
3. Chemotherapy is not effective and is given for a prolonged period of time.
4. Treatment surgical and chemotherapy are ineffective when the mycetoma is due to fungi.

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