Perhaps genetic susceptibility; worldwide; increased in Cushing's patients. Tinea corporis seen in children with puppy or kitten; T. capitis especially common in black children

Sx:Annular, red, scaly, pruritic rash; on foot arch can form vesicles like "big dyshydrotic eczema"

Si:Scaling rash head, body, groin, between toes; annular w scale on outside of ring, ringworm appearance often; distorted white flaking nails w onychomycosis. Wood's lamp illumination shows yellow-green fluorescence w Microsporum spp. In beard, can look like antibiotic unresponsive folliculitis, which has no scale and is KOH neg

Secondary bacterial infections; kerion of scalp, inflammation that can lead to severe scarring

r/o other causes of similar round lesions like granuloma annulare (Granuloma Annulare), which has no scale and is KOH neg, and pityriasis rosea (Pityriasis Rosea), which has scale around the inside of the ring; pustular psoriasis when on soles and/or palms; in groin, ERYTHRASMA, a diphtheroid skin infection that fluoresces coral red in Wood's lamp light, rx w topical or oral erythromycin

Lab: Bact:KOH prep shows branching hyphae. Culture on Sabouraud's media

Rx:(Med Let 1993;35:77)

TOPICAL

• Ciclopirox (as Penlac nail lacquer) (Med Let 2000;42:51) qd to nails, wash off weekly, 10% effective initially and 1/2 those relapse w/i 3 mo, $180/yr
• Clotrimazole (Lotrimin) OTC, may be more effective than tolnaftate and covers candida (Med Let 1976;18:101) and and inexpensive and OT C
• Tolnaftate (Tinactin); doesn't work in scalp, hair, nails, palms, and soles
• Haloprogen (Halotex); expensive, absorbed (5%) (Med Let 1988;30:99), etc. (Antifungal Agents)
• Selenium sulfide shampoo 2.5% (Selsun) to decrease spore count and intrafamilial spread
• Naftifin (Naftin) cream or gel qd

ORAL (Am J Med 2007;120:791; ACP J Club 2008;148:14; J Am Brd of Fam Pract 2000;13:268) (use only for nails, topical resistant skin infections, or in immunocompromised; E. Ringle rx's only w pos KOH and doesn't rx toenails because of resistance and drug toxicity)

• 1st: Terbinefin (Lamisil) (Antifungal Agents) for nails, 250 mg po qd × 12+ wks, <70% effective; $650/3 mo; pulsed rx w 500 mg qd 1/4 wks × 3-4 mos slightly less effective slightly less effective
• 2nd: Itraconazole 100 mg po qd x 2-4 wk for T. corporis; 200 mg po qd x 3-6 mo for nails, $1200/3 mos (Med Let 1996;38:5), or pulsed doses of 200 mg po bid 1/4 wks x 3-4 mos
• 3rd: Fluconazole 300-400 mg po q1wk × 6-9 mo for toenails; 150-300 mg q1wk × 3 mo for fingernails (unapproved by FDA) 90% effective (Maine Medicaid Drug Utilizaton Rv 2007)
• 4th: Griseofulvin 250 mg po bid × 4 wk for skin, × 6-8 wk for T. pedis, 500 mg po bid × 6+ mo for fingernails, × 12+ mo for toenails, $750; in children w T. capitis, 15 mg/kg qd × 8 wk; best absorption with a fatty meal, eg, whole milk or ice cream