A skin scraping and potassium hydroxide (KOH) prep confirmed the presence of branching hyphae, consistent with tinea corporis. The large size of this plaque could have easily made this diagnosis more difficult. When tinea corporis is suspected, look at the edge of the plaque; there is often thin scale and sometimes small pustules corresponding to follicular involvement.
Commonly called by the misnomer “ringworm,” tinea corporis is a skin infection caused by a wide variety of dermatophytes and affects all ages, sexes, and skin types. Trichophyton, Microsporum, and Epidermophyton species are frequently isolated.1 Patients with atopic dermatitis or weakened immunity may be more susceptible to more frequent or long-lasting episodes. Diabetes may have contributed to the extent of the disease in this case.
Patients with tinea corporis present with one or several annular patches to plaques that grow in size. When the source of contagion is an animal, inflammation can be dramatic. In the case above, there was minimal to no itching and the patient didn’t notice the rash; thus, it was able to enlarge for months.
Treatment options include systemic and topical antifungal therapy. Consideration should be given to the severity of the disease and causal organism. Azoles, terbinafine, and ciclopirox are common treatment options. Topical therapy with an appropriately selected antifungal for 1 to 6 weeks, based on clinical response, is safe and effective. It is important to consider other foci of infection, including the feet and hands. More extensive disease may be treated with oral therapy such as terbinafine, fluconazole, or itraconazole.
Because of the extent of the disease and the challenge of effective coverage with topical therapy, this patient was treated with oral terbinafine 250 mg daily for 3 weeks. The plaque cleared completely.
Photos and text for Photo Rounds Friday courtesy of Jonathan Karnes, MD (copyright retained). Dr. Karnes is the medical director of MDFMR Dermatology Services, Augusta, ME.