Superficial, Cutaneous, Subcu Myco

• Superficial Mycoses are the most common fungal infections of the skin
• Superficial Mycoses result in little to no inflammation
• Examples of Superficial Mycoses include Malassezioses, Pityriasis versicolor, and Seborrheic dermatitis
• Malassezia sp. is a common cause of superficial mycoses
• White Piedra is caused by Trichosporon species
• Black Piedra is caused by Piedraia hortae
• Tinea nigra is caused by Hortaea werneckii
• Cutaneous fungal infections of hair and nails are caused by Dermatophytes
• Examples of Dermatophytes include Trichophyton sp., Epidermophyton sp., and Microsporum sp.
• Tinea is another term for Dermatophytosis
• Different types of Tinea infections include Tinea barbae, Tinea capitis, Tinea corporis, Tinea pedis (Athlete's foot), and Tinea unguium (Onychomycosis)
• Malassezia sp. are Basidiomycota yeasts commonly found on human and animal skin
• Malassezia sp. is common in warm, humid climates
• T cell deficiencies are associated with significant disease related to Malassezia sp.
• Pityriasis (Tinea) versicolor is a chronic skin infection caused by Malassezia sp.
• Pityriasis (Tinea) folliculitis is characterized by pruritic follicular papules and pustules
• Seborrheic dermatitis, also known as dandruff, is a mild form of infection caused by Malassezia sp.
• Direct microscopy with 10% KOH and stain is diagnostic for Malassezia sp.
• White Piedra is caused by Trichosporon sp. and is characterized by nodules on the hair shaft
• Black Piedra is caused by Piedraia hortae and is characterized by nodules on the hair shaft
• Tinea nigra caused by Hortaea werneckii is a superficial, asymptomatic skin infection
• Cutaneous Mycoses, also known as Ringworm, present as circular, scaly patches on the skin
• Examples of Cutaneous Mycoses include Tinea corporis, Tinea pedis (Athlete's foot), Tinea manus, and Tinea cruris (jock itch)
• Trichophyton mentagrophytes is the most common cause of Tinea pedis (Athlete's foot)
• Diagnosis of Tinea infections can be done through hair fluorescence using Wood's lamp
• Tinea pedis (Athlete's foot) can present in different forms such as Moccasin, Interdigital, Inflammatory, and Ulcerative
• Tinea cruris (jock itch) commonly affects post-pubertal males in warm climates
• Onychomycosis, known as Tinea unguium, is a nail infection that can be caused by Dermatophytes
• Onychomycosis may present with hyperkeratosis, yellow-brown discoloration, and onycholysis
• Tinea pedis:

  • Hyperkeratosis, yellow-brown discoloration, onycholysis common
• Differential diagnosis for Psoriasis
• Cutaneous Mycoses:

  • Microsporum canis following contact with infectious kittens
• Tinea corporis:

  • Dermatophytosis of glabrous skin of the face, trunk and limbs excluding beard
  • Worldwide distribution with highest prevalence in warm, humid climates
  • No preference for gender or age
  • Risk factors: Diabetes, Cushing syndrome, HIV and immunocompromised at high risk for infection
  • Outdoor occupation, close association with animals, contact sports
  • Presents noninflammatory oval to round lesions to scaly plagues, hair follicle involvement, bacterial infections
  • Geophilic/Zoophilic – inflammatory, pustules, vesicles
  • Diagnosis by KOH-Calcofluor smear & culture
• Trichophyton schoenleinii:

  • Tinea capitis, ringworm of scalp, favus
  • Found in developing countries with worldwide distribution
  • Most common in prepubescent children (3 to 7 y.o.) with equal distribution between male & female
  • Zoophilic – Microsporum canis most common in the world, Trichophyton tonsurans most common in US and Western Europe
  • Lesions range from dry & scaly patches of alopecia to inflammatory pustules
  • Cervical lymphadenopathy common
  • Diagnosis by hair examination to determine if ecto or endothrix
  • Cultures of skin scraping, hair often required – 21 days to growth
• • Systemic drug treatment common with T. tonsurans
• Dematiaceous fungi:

  • Septate, dark-colored hyphae, colony reverse dark green to black
  • Produces melanin pigment = brown, black coloring
  • Hyaline hyphae = NO pigment production
  • Dermatophyte - Derma = skin, phyte = pathological growth or plant with specific habitat
  • Keratinophilic, uses keratin as a nitrogen source
  • Causative agents of ringworm (tinea)
  • Common soil saprobes
  • Infection requires traumatic introduction to deep tissue
  • Lesions remain localized just below the skin and rarely become systemic
• Subcutaneous Mycoses:

  • Chromoblastomycosis: Chronic localized infection of the skin and subcutaneous tissue following traumatic implantation of the etiologic agent
  • Mycetoma: Syndrome characterized by tumefaction, draining sinuses and granules involving cutaneous and subcutaneous tissue, fascia and bone
  • Phaeohyphomycosis: Catch all term for infection with dematiaceous fungal isolates
  • Lymphocutaneous sporotrichosis/Sporotrichosis: A chronic infection limited to cutaneous and subcutaneous tissue that may spread along lymphatics and may cause erythema, ulcerations and nodule formation
• Chromoblastomycosis:

  • Dematiaceous infection from soil, vegetation, inoculation most common in feet, spread by lymphatics
  • Chronic, nonhealing years/decades, large, flat to thick, tough wartlike, tumorous lesions
  • Inflammation, fibrosis, and abscess formation occur in surrounding tissues
  • Worldwide, majority cases in tropical and subtropical regions like South America and Africa
  • Diagnosis by biopsy and histological exam with tissue invasion of sclerotic bodies
• Direct microscopy of tissue is necessary to differentiate between chromoblastomycosis and phaeohyphomycosis

  • Key distinguishing feature is the microscopic morphology of the fungal cells within tissues
  • KOH and GMS of infected tissue show golden brown sclerotic bodies distinctive from budding yeast
• Phaeohyphomycosis:

  • Infection with dematiaceous fungi
  • Worldwide distribution with Southern US having sinus infections and tropical regions having feet infections
  • Healthcare-associated infection from environmental contaminants of injectables
  • Infection following traumatic implantation can lead to superficial lesions to deep-seated infections like endocarditis, sinusitis, mycotic keratitis, pulmonary and systemic abscesses, and brain involvement