Mycetoma

Mycetoma - Madura's Foot Mess

• Chronic, suppurative, granulomatous infection of subcutaneous tissue, fascia, and bone.
• Classic Triad:
  • Painless subcutaneous mass (tumefaction).
  • Multiple sinuses.
  • Discharge containing grains (microcolonies).
• Types & Causative Agents (Grain Color):
  • Eumycetoma (Fungal):
    • Madurella mycetomatis (Most common in India; Black grains).
    • Acremonium falciforme, Fusarium spp. (White grains).
  • Actinomycetoma (Bacterial - Filamentous):
    • Nocardia brasiliensis (Most common worldwide; Yellow/White grains).
    • Actinomadura madurae (White/Yellow grains).
    • Streptomyces somaliensis (Yellow/Brown grains).

⭐ Madurella mycetomatis is the most common cause of eumycetoma in India, producing black grains, while Nocardia brasiliensis is the most common cause of actinomycetoma globally.

• 📌 Remember: Grain color is a crucial diagnostic clue!

Mycetoma - Spotting Grainy Trouble

• Chronic, progressive granulomatous infection of skin, subcutaneous tissue, fascia, and bone.
• Clinical Triad:
  • Painless subcutaneous mass (tumefaction)
  • Multiple sinuses
  • Discharge containing grains (colonies of causative agent)
• Types & Grains:
  • Eumycetoma (Fungal):
    • Causative agents: Madurella mycetomatis (most common, black grains), Aspergillus spp., Fusarium spp.
    • Large, pigmented (black, yellow, white) grains.
    • Lesions: Well-defined, hard; bone involvement late, lytic lesions.
  • Actinomycetoma (Bacterial):
    • Causative agents: Nocardia brasiliensis (most common), Actinomadura madurae, Streptomyces somaliensis.
    • Small, fine, white, yellow, or red grains.
    • Lesions: Ill-defined, soft, more inflammatory; bone involvement early, extensive, osteosclerotic with periosteal reaction.

⭐ Dot-in-circle sign on MRI/USG is highly suggestive of mycetoma, representing central hypointense dot (grain) surrounded by hyperintense inflammatory granuloma.

• 📌 Mnemonic: MADura (Eumycetoma - Madurella) vs NOt MAD (Actinomycetoma - Nocardia).

Mycetoma - Nailing the Culprit

• Clinical Triad: Painless subcutaneous swelling (tumefaction), multiple discharging sinuses, visible grains/granules.
• Grains - Key to Diagnosis:
  • Actinomycetoma (Bacterial): Fine (<1 mm), yellowish/whitish/reddish. Common: Nocardia spp., Actinomadura madurae.
  • Eumycetoma (Fungal): Coarse (>1 mm), black/dark or white/pale. Common: Madurella mycetomatis (black), Scedosporium apiospermum (white).
• Diagnostic Toolkit:
  • Microscopy: Grains (KOH, Gram stain).
  • Culture: Sabouraud Dextrose Agar (SDA) for fungi; Lowenstein-Jensen (LJ) or Blood-Cysteine-Glucose Agar (BCGA) for aerobic actinomycetes.
  • Histopathology: H&E, PAS, GMS.
  • Imaging:
    • X-ray: Bone involvement (cavities, osteolysis).
    • USG/MRI: Extent, "dot-in-circle" sign (MRI).

⭐ The "dot-in-circle" sign on T2-weighted MRI is highly characteristic of mycetoma, representing a central grain surrounded by inflammatory granulation tissue.

Mycetoma - Kicking Out Invaders

• Chronic granulomatous infection: skin, subcutaneous tissue, fascia, bone.
• Triad: Painless swelling, multiple sinuses, discharge with grains (color varies).
• Types:
  • Actinomycetoma (bacterial): Nocardia, Actinomadura. Grains: yellow, white, red. Responds to antibiotics.
  • Eumycetoma (fungal): Madurella mycetomatis (commonest). Grains: black, dark. Antifungals + surgery.
• Diagnosis: Clinical, grain microscopy (KOH, Gram), culture, imaging (X-ray, USG, MRI).

  ⭐ "Dot-in-circle" sign on MRI/USG is characteristic of eumycetoma.

• 📌 Mnemonic (Actinomycetoma): "Welsh ACTINg" (Welsh regimen for ACTINomycetoma).

High‑Yield Points - ⚡ Biggest Takeaways

• Mycetoma: Chronic granulomatous infection of skin, subcutaneous tissue, and bone.
• Key triad: Painless subcutaneous mass, multiple sinuses, and discharging grains.
• Two types: Eumycetoma (fungal) and Actinomycetoma (bacterial); latter commoner in India.
• "Madura foot" is the classic presentation.
• Grains (color, consistency) are diagnostic; sulphur granules in Actinomycetoma.
• Actinomycetoma treatment: long-term antibiotics (e.g., Welsh regimen).
• Eumycetoma treatment: antifungals and often surgery.