A 73-year-old woman comes to the office due to an 8-month history of thickening and discoloration of multiple toenails in both feet. The patient has had no associated pain but frequently snags her stockings on the nails. Medical history is notable for rheumatoid arthritis and hypertension. The patient does not use tobacco or alcohol. Examination findings are as shown in the exhibit. Which of the following is the most likely diagnosis?

Question

A 73-year-old woman comes to the office due to an 8-month history of thickening and discoloration of multiple toenails in both feet.  The patient has had no associated pain but frequently snags her stockings on the nails.  Medical history is notable for rheumatoid arthritis and hypertension.  The patient does not use tobacco or alcohol.  Examination findings are as shown in the exhibit.  Which of the following is the most likely diagnosis?

Quizplus · Accepted Answer

11ec25c8_d385_2cf5_bc81_69322d94f8d9_MD0003_00 This patient has extensive thickening and discoloration of the toenails consistent with onychomycosis (tinea unguium). Onychomycosis is a chronic dermatophyte infection of the nails most commonly caused by Trichophyton rubrum and similar fungi. The same organisms can affect the interdigital spaces of the toes, leading to tinea pedis; manifestations include itching, erythema (as in this patient), and scaling. Onychomycosis is typically painless, but the thickening and roughness of the nails may cause problems with stockings and footwear. In addition, fissuring of the surrounding skin may allow the entry of bacteria, leading to paronychia. The diagnosis is confirmed by potassium hydroxide microscopy of nail scrapings. A number of topical and oral antifungal agents (eg, terbinafine) are effective, but prolonged treatment may be necessary; treatment failure is common. (Choice A) Onychomycosis due to yeasts (eg, Candida species) is usually seen in the fingernails, often in patients who have chronic mucocutaneous candidiasis or work frequently in wet conditions. Yeast onychomycosis is uncommon in the toenails. (Choice B) Iron deficiency is occasionally associated with koilonychia (spoon nails), which is characterized by reverse curvature of the nails. koilonychia (spoon nails) (Choice C) Involvement of the nails by lichen planus produces longitudinal ridges, fissuring, and thinning, not thickening, of the nail plate. longitudinal ridges, fissuring, and thinning (Choice D) Pseudomonas aeruginosa can colonize the nail plate and is often seen in patients with underlying onychomycosis due to fracturing and porosity of the nail. When this occurs, it typically produces a characteristic green discoloration. green discoloration (Choice E) Psoriasis of the nail presents with nail pitting, oil spots, and separation of the nail plate from the nail bed (onycholysis). nail pitting oil spots Educational objective: Onychomycosis is a chronic dermatophyte infection of the nails most commonly caused by Trichophyton rubrum and similar fungi. It is characterized by thickening, roughness, and discoloration of the nails. The diagnosis is confirmed by potassium hydroxide microscopy of nail scrapings.

A 73-Year-Old Woman Comes to the Office Due to an 8-Month