Chromoblastomycosis

• Chronic cutaneous fungal implantation infection

Background

Microbiology

• Mostly members of the family Herpotrichiellaceae within the order Chaetothyriales
• Fonsecaea species
  • Fonsecaea pedrosoi (most common), which is present in Brazil, Mexico, Sri Lanka, Japan, and Madagascar
  • F. monophora and F. pugnacius, which both have neurotropism
  • F. nubica
• Cladophialophora species
  • Cladophialophora carrionii
  • Cladophialophora samoensis
• Cladosporium carrionii
• Phialophora verrucosa
• Rhinocladiella aquaspersa
• Exophiala species, which is a black yeast-like mold
  • Exophiala dermatitidis

History

• Known by many names worldwide, including chapa (Cuba), figueira or formigueiro (Brazil), sundo or sustra (South America), foratra, gajo-miala, or didra (Madagascar)
• Other medical names include black or yellow blastomycosis

Pathophysiology

• Characterized by a non-protective TH2 cell response

Risk Factors

• Agriculture work
• Adult males (thought to be a protective effect of progesterone)

Epidemiology

• More common in tropics and subtropics worldwide
• In the US, Fonsecaea pedrosoi, Fonsecaea monphora, and Phialophora verrucosa
• Higher rates in Mexico, Brazil, other parts of northern South America, Madagascar, and China
• Relatively high rate in Japan, as well

Clinical Manifestations

• Chronic localized fungal infection of the skin and subcutaneous tissue that produces raised, scaly lesions, usually in the lower extremities
  • Lesions are warty, cauliflower-like
  • Does not usually involve deeper structures like muscle or bone
• Typically an implantation infection secondary to traumatic inoculation
  • Plants: wood, straw, grass, thorns, palm trees, bamboo, coconut shells, cacti
  • Animals: insect stings, cow stomp, buck rear, cock spine, caterpillars, leeches
  • Farming tools: hoes, axes, knives, and mills
  • May be associated with natural disasters (hurricanes and flooding), motor vehicle collisions, bricks, and shoes
• Severity based on

Differential Diagnosis

• Fungi
  • Other implantation mycoses: sporotrichosis, eumycetoma, and lacaziosis
  • Dimorphic fungi
• Bacteria
  • Cutaneous non-tuberculous mycobacteria
  • Leprosy
  • Nocardiosis
  • Actinomycosis
  • Yaws
  • Tertiary syphilis
• Parasites
  • Leishmaniasis
  • Rhinosporidioisis
• Viruses: Human papilloma virus
• Non-infectious causes
  • Squamous cell carcinoma
  • Mycosis fungoides (cutaneous T-cell lymphoma)
  • Sarcoidosis
  • Systemic lupus serythematosus

Diagnosis

• Skin scrapings or skin biopsy followed by histology and culture
  • Try to get areas where there are black specks ("cayenne pepper")
• Histology
  • Pathognomonic muriform cells (copper penny cells)
• Culture
  • Resistant to cycloheximide
  • May take up to 6 weeks to grow

Management

• Surgical excision is the main therapy
• Can also treat with cryotherapy, laster therapy, or heat therapy
• Antifungals include itraconazole, posaconazole, isavuconazole, and terbinafine
  • Fonsecaea species are relatively difficult to treat

Further Reading

• Chromoblastomycosis. Clin Microbiol Rev. 2017;30(1):233–276. doi: 10.1128/CMR.00032-16