Tropical Mycoses

Tropical Mycoses: Overview - Fungal Heat Wave

Tropical Mycoses: Fungal infections prevalent in hot, humid climates, often with distinct clinical presentations.

• Predisposing Factors: High temperature & humidity, skin trauma (e.g., thorns, splinters), barefoot walking, poor hygiene, malnutrition.
• Classification:
  • Superficial: E.g., Tinea versicolor, Piedra.
  • Cutaneous: E.g., Dermatophytosis (tropical patterns like Tinea imbricata).
  • Subcutaneous: E.g., Mycetoma, Sporotrichosis, Chromoblastomycosis.
  • Systemic (with skin signs): E.g., Histoplasmosis, Paracoccidioidomycosis.

⭐ Mycetoma ("Madura foot") classically presents with a triad: painless subcutaneous mass, multiple sinuses, and discharge containing granules (grains).

Subcutaneous Mycoses: Mycetoma & Sporotrichosis - Deep Tissue Terrors

Mycetoma

• Chronic granulomatous infection of skin, subcutaneous tissue, fascia, bone.
• Etiology: Eumycetoma (fungal) vs. Actinomycetoma (bacterial).
• Clinical Triad: Painless firm subcutaneous swelling, multiple discharging sinuses, visible grains (colonies).
• Diagnosis: Grains (color, size, consistency), imaging (X-ray, MRI for bone involvement), culture.
• Management: Medical (antifungals/antibiotics), surgical debridement/amputation for extensive disease.

Sporotrichosis

• Etiology: Sporothrix schenckii (dimorphic fungus), often from trauma with contaminated plants (rose thorns 📌 "Rose gardener's disease").
• Clinical Forms:
  • Lymphocutaneous: Most common; nodule at inoculation site → chain of painless nodules along lymphatics.
  • Fixed cutaneous: Solitary plaque/ulcer, non-lymphatic spread.
  • Disseminated: Rare, in immunocompromised.
• Diagnosis: Culture (gold standard), biopsy (cigar-shaped yeasts, Asteroid bodies - Splendore-Hoeppli phenomenon).
• Management: Itraconazole (DOC for cutaneous/lymphocutaneous), Saturated Solution of Potassium Iodide (SSKI) (alternative).

⭐ Asteroid bodies (Splendore-Hoeppli phenomenon) in sporotrichosis are antigen-antibody complexes surrounding the yeast, not specific to sporotrichosis but highly suggestive in the right clinical context.

Subcutaneous Mycoses: Chromoblastomycosis & Co. - Crusted Calamities

• Chromoblastomycosis:

  • Etiology: Dematiaceous (pigmented) fungi like Fonsecaea pedrosoi, Cladophialophora carrionii.
  • Clinical: Chronic verrucous, crusted, "cauliflower-like" plaques, often on feet/legs.
  • Diagnosis: Key is finding sclerotic bodies (Medlar bodies, "copper pennies") on microscopy/biopsy.

    ⭐ Sclerotic bodies (Medlar bodies, copper pennies) are pathognomonic for Chromoblastomycosis.

  • Management: Itraconazole (200-400 mg/day), terbinafine. Adjuncts: heat therapy, cryosurgery, surgical excision.

• Other Subcutaneous Mycoses (Briefly):

  • Lobomycosis: Keloidal nodules; Lacazia loboi (yeast chains).
  • Subcutaneous Phaeohyphomycosis: Cysts/abscesses; pigmented hyphae in tissue (no grains/sclerotic bodies).

Systemic Mycoses: Dimorphic Threats - Shape‑Shifting Spores

• Histoplasmosis (H. capsulatum):
  • var. capsulatum (American): AIDS-associated; disseminated disease presents with skin papules, nodules, ulcers.
  • var. duboisii (African): Primarily granulomatous skin & bone lesions; often larger.
  • Dx: Biopsy (intracellular yeasts in macrophages), culture, antigen detection.
  • Mgmt: Itraconazole (mild-mod); Amphotericin B (severe).
• Paracoccidioidomycosis (P. brasiliensis):
  • Geography: Latin America.
  • Clinical: Pulmonary involvement; mucocutaneous lesions (painful 'mulberry-like' oral/nasal ulcers).
  • Dx: Microscopy (yeast with multiple buds: 'mariner’s wheel'). 📌 Pilot's Wheel.
  • Mgmt: Itraconazole (DOC, 6-12 months); Amphotericin B (severe).

  ⭐ In Paracoccidioidomycosis, the characteristic 'mariner's wheel' appearance of P. brasiliensis yeast with multiple budding is a key diagnostic feature. oka

High‑Yield Points - ⚡ Biggest Takeaways

• Mycetoma (Madura foot) presents with painless subcutaneous nodules, sinuses, and discharge of grains.
• Chromoblastomycosis shows verrucous plaques and characteristic sclerotic bodies (Medlar bodies, copper pennies) on microscopy.
• Sporotrichosis ("rose gardener's disease") typically has lymphocutaneous spread; microscopy reveals cigar-shaped yeasts.
• Lobomycosis features chronic keloidal lesions with chains of yeast cells (Lacazia loboi).
• Rhinosporidiosis causes friable, polypoidal nasal or ocular lesions with large sporangia containing endospores.
• Phaeohyphomycosis is an infection caused by dematiaceous (pigmented) fungi, presenting with diverse clinical forms depending on the site and host immunity.