A 42-year-old man comes to the office due to a rash. For the last 2 months, he has had a slowly expanding rash on his right upper arm associated with moderate itching. He recently adopted 2 cats and is unsure if he has had any animal bites. Medical history is unremarkable, and the patient takes no medications. Vital signs are normal. Skin examination findings are shown in the exhibit. There is no lymphadenopathy. Minor scratches are present over both arms. Which of the following is the most appropriate treatment for this patient's skin condition?

Question

A 42-year-old man comes to the office due to a rash.  For the last 2 months, he has had a slowly expanding rash on his right upper arm associated with moderate itching.  He recently adopted 2 cats and is unsure if he has had any animal bites.  Medical history is unremarkable, and the patient takes no medications.  Vital signs are normal.  Skin examination findings are shown in the exhibit.  There is no lymphadenopathy.  Minor scratches are present over both arms.  Which of the following is the most appropriate treatment for this patient's skin condition?

Quizplus · Accepted Answer

11ec25c8_d390_ecde_bc81_8310a83922d5_MD0003_00 This patient has a slowly expanding, annular, pruritic rash with a raised border and central clearing consistent with tinea corporis (TC). TC, sometimes called ringworm, is a superficial dermatophyte infection caused by Trichophyton rubrum and similar species. The fungi thrive in warm, moist areas (eg, shower surfaces, pools, gym mats) and can be transmitted by skin-to-skin contact, contact with animals (eg, cats), or via fomites. The diagnosis of TC is generally apparent on inspection, but potassium hydroxide examination of skin scrapings can confirm the diagnosis in severe, atypical, or refractory cases. TC is usually treated with topical antifungals (eg, terbinafine, miconazole). Oral antifungals (eg, fluconazole, griseofulvin) are also effective but are typically reserved for patients with widespread or refractory disease. (Choice A) Clindamycin gel is used in the treatment of inflammatory or nodular acne vulgaris. Acne most commonly affects the face and does not cause annular lesions. (Choice B) High-potency topical corticosteroids (eg, fluocinonide) are used in the treatment of psoriasis, which causes scaly plaques but most commonly affects the extensor surfaces of the elbows and knees. Pruritus and central clearing are possible but not characteristic. (Choice C) Nystatin is effective for infections caused by Candida species, but it is not effective against the dermatophytes responsible for TC. (Choice D) Azithromycin is used for the treatment of Bartonella henselae infection (ie, catscratch disease). It presents with an erythematous papule or nodule at the site of inoculation, often with associated regional adenopathy. erythematous papule or nodule (Choice E) Doxycycline is effective against Lyme disease. This disorder causes an annular rash with central clearing, but the lesions do not have a raised border and are frequently associated with systemic symptoms (eg, fatigue, myalgias). annular rash Educational objective: Tinea corporis is a superficial dermatophyte infection characterized by a slowly expanding, pruritic rash with a raised border and central clearing. The fungi are transmitted by skin-to-skin contact, contact with animals, or via fomites. The diagnosis is generally apparent on inspection but can be confirmed with potassium hydroxide examination of skin scrapings. First-line treatment is a topical antifungal (eg, terbinafine, miconazole).

A 42-Year-Old Man Comes to the Office Due to a Rash