Cutaneous Mycoses

Overview
  • A variety of dimorphic fungal species cause Cutaenous Mycoses (AKA "Dermatophytoses") which are fungal infections that can affect keratinized tissues including skin, hair, and nails. These organism release an enzyme "Keratinase" which can digest keratin, thus liberating nutritional molecules. Because the epidermis can be invaded by these organisms they do elicit an immune response which generally results in erythema and pruritis. Dermpatophytoses are largely classified according to their tropism for particular anatomic areas. Their names erroneously refer to worms (Tinea), followed by the latin name for the anatomic region infected.
Clinical Consequences
  • Tinea corporis (corpus = body): Presents as expanding, raised annular lesion with an inflamed, erythematous leading edge and a healing center. Because the lesion looks as if caused by a sub-cutaneous ring-shaped worm, the lesion was historically termed "Ring Worm"
  • Tinea cruris (crux = crotch): Pruritis of perineum and scrotum which is also popularly known as "Jock Itch"
  • Tinea pedis (pedis = foot): Manifests as cracking, scaling of foot's skin caused by hyperkeratosis and is popularly known as athlete's foot
  • Tinea capitis (capit = head): Manifests as scaly lesions on the scalp which may be accompanied by alopecia
  • Tinea uniguium (unig = nail): Manifests as brittling and thickening of fingernails and is also known as onychomycosis
Diagnosis
  • Skin scrapings treated with potassium hydroxide (KOH) reveal branched hyphae. Wood's Lamp will cause certain species to fluoresce
Treatment
  • Topical preprations of many azole antifungal antibiotics such as ketoconazole or itraconazole is often sufficient for treatment. Cutaneous antifungals such as griseofulvin or terbinafine can also be used.