The Common Vein

• What is it:
  Mycetoma is a chronic, localized, and progressive granulomatous infection of the skin, subcutaneous tissue, and sometimes underlying bone. It is characterized by the presence of painless nodules, sinuses, and discharge containing grains.
• Etymology:
  The term “mycetoma” originates from the Greek words mykes (fungus) and oma (tumor), indicating its fungal association.
• AKA:
  Madura foot (when occurring in the foot).
• What causes it:
  Mycetoma is caused by either:
  • Fungal agents (eumycetoma): e.g., Madurella species, Aspergillus.
  • Bacterial agents (actinomycetoma): e.g., Nocardia, Actinomadura, Streptomyces.
    The infection is usually acquired through traumatic inoculation of the causative agent from soil or plant material.
• What is the result:
  If untreated, mycetoma can cause:
  • Extensive tissue destruction.
  • Deformity.
  • Secondary bacterial infections.
  • Osteomyelitis in advanced cases.
• How is it diagnosed:
  Diagnosis involves:
  • Clinical examination: Identifying the triad of swelling, discharging sinuses, and granules in the discharge.
  • Laboratory tests: Microscopy, culture, and histopathology of granules.
  • Imaging studies:
    • Plain radiography: Shows soft tissue swelling, with possible bone involvement in advanced stages.
    • Ultrasound: Hypoechoic areas with posterior acoustic enhancement (fluid-filled sinuses).
    • MRI: Useful for assessing soft tissue extent, sinus tracts, and bone involvement.
    • CT scan: Shows osseous destruction, sequestration, or periosteal reaction in severe cases.
• How is it treated:
  Treatment depends on the causative agent:
  • Eumycetoma (fungal): Prolonged antifungal therapy (e.g., itraconazole) with surgical debridement.
  • Actinomycetoma (bacterial): Long-term antibiotics (e.g., sulfonamides, amikacin, rifampicin).
  • Advanced cases: Surgical excision or amputation may be required.
• Radiological implications:
  • Soft tissue involvement: Nodules and sinuses visible on ultrasound and MRI.
  • Bone involvement: Lytic lesions, sclerosis, or periosteal reaction seen on CT or radiographs.
  • Differentiating fungal vs. bacterial mycetoma: Fungal mycetomas often show larger and more organized lesions compared to bacterial.
• Key points and pearls:
  • Mycetoma should be considered in patients with chronic localized swelling and discharging sinuses, especially in endemic regions.
  • Imaging helps determine the extent of the disease and guides surgical planning.
  • Delayed treatment can result in significant morbidity, including deformity and limb loss.
  • Early microbiological identification of the causative agent is crucial for effective management.

TCV Format for Disease: Pulmonary Mycetoma

• What is it:
  Pulmonary mycetoma is a fungal infection of the lung characterized by the formation of a fungal ball (mycetoma) within a pre-existing pulmonary cavity. It is typically caused by saprophytic colonization of the cavity by fungi, most commonly Aspergillus species.
• Etymology:
  The term “mycetoma” originates from the Greek words mykes (fungus) and oma (tumor), highlighting its fungal origin.
• AKA:
  Pulmonary fungal ball, Aspergilloma (when caused by Aspergillus species).
• What causes it:
  • Causative organisms:
    • Most commonly: Aspergillus fumigatus (aspergilloma).
    • Other fungi: Candida, Fusarium, or Zygomycetes.
  • Predisposing factors:
    • Pre-existing pulmonary cavities: e.g., from tuberculosis, sarcoidosis, emphysema, bronchiectasis, or prior abscess.
    • Immunocompromised states: e.g., HIV/AIDS, post-transplant, prolonged steroid use.
• What is the result:
  • Potential complications:
    • Hemoptysis (sometimes massive and life-threatening).
    • Progressive destruction of adjacent lung tissue.
    • Secondary infections.
• How is it diagnosed:
  • Clinical findings:
    • Chronic cough, hemoptysis, and sometimes asymptomatic presentation.
  • Imaging studies:
    • Chest CT (preferred modality):
      • Rounded soft tissue density (“fungal ball”) within a pre-existing cavity.
      • Air crescent sign: Air surrounds the fungal mass.
      • Adjacent pleural thickening.
    • Plain chest radiography:
      • Same findings as CT but less detailed.
      • Fungal ball moves with a change in patient position.
  • Microbiological tests:
    • Sputum culture or bronchoscopy to identify the fungal species.
  • Laboratory tests:
    • Elevated serum IgE levels or positive Aspergillus precipitins (if allergic or invasive aspergillosis is suspected).
• How is it treated:
  • Asymptomatic or mild cases: Observation or antifungal therapy (e.g., itraconazole).
  • Symptomatic cases:
    • Antifungal treatment.
    • Bronchial artery embolization for massive hemoptysis.
    • Surgical resection in select cases (e.g., localized disease with recurrent bleeding).
  • Advanced cases in immunocompromised patients: May require systemic antifungals and aggressive supportive care.
• Radiological implications:
  • Chest CT:
    • Definitive for identifying a fungal ball and assessing cavity morphology.
  • MRI:
    • Rarely needed but may differentiate fungal balls from neoplasms or blood clots.
  • PET-CT:
    • Increased uptake in active infections or malignancy; less uptake in simple fungal balls.
• Key points and pearls:
  • Pulmonary mycetoma should be considered in patients with hemoptysis and a history of cavitary lung disease.
  • The “air crescent sign” is a hallmark finding for fungal balls in CT imaging.
  • Management strategies depend on symptoms, extent of disease, and underlying lung pathology.
  • Prophylactic antifungal therapy is not typically indicated for asymptomatic fungal balls but is critical in immunocompromised patients at risk for invasive fungal disease.