Dermatology and Nail Disorders Flashcards

Pitted keratolysis presents with malodorous, punched-out erosions on the plantar surface. Which bacteria is the primary causative agent?

Answer: Kytococcus sedentarius (Micrococcus sedentarius)

Kytococcus sedentarius (formerly Micrococcus sedentarius) and Corynebacterium species produce proteases that create the characteristic pitted erosions of pitted keratolysis.

A patient presents with a tender, pulsatile, bluish nodule under the nail of the hallux that causes severe pain with cold exposure. What is the most likely diagnosis?

Answer: Glomus tumor

A glomus tumor is a benign vascular hamartoma arising from the glomus body that classically presents as a triad of point tenderness, cold sensitivity, and pain — often in the subungual region.

Erythrasma affecting the web spaces of the foot is caused by which organism and best treated with which antibiotic?

Answer: Corynebacterium minutissimum; erythromycin

Erythrasma is a superficial bacterial infection caused by Corynebacterium minutissimum, characterized by coral-red fluorescence under Wood's lamp and treated with oral erythromycin.

Which nail disorder is characterized by excessive lateral curvature of the nail plate that pinches the soft tissue without penetrating it, often causing pain and onycholysis?

Answer: Pincer nail (involuted nail)

Pincer nail (trumpet nail) involves transverse overcurvature of the nail plate that compresses the underlying nail bed but does not penetrate the lateral fold as in onychocryptosis.

Beau's lines (transverse depressions across the nail plate) occur as a result of:

Answer: Temporary arrest of nail matrix cell proliferation

Beau's lines form when systemic illness, severe stress, or nutritional deficiency temporarily halts nail matrix proliferation, creating a transverse groove that grows distally with the nail.

Which of the following accurately describes the 'nail-patella syndrome' finding relevant to podiatric practice?

Answer: Absence of the thumbnail and hypoplastic toenails with associated renal dysplasia

Nail-patella syndrome (hereditary osteo-onychodysplasia) features hypoplastic or absent thumbnails, dysplastic toenails, absent or hypoplastic patellae, and nephropathy.

A diabetic patient presents with a macerated, white hyperkeratotic plaque in the third web space. KOH prep reveals hyphae. Which topical antifungal is most appropriate as initial therapy?

Answer: Clotrimazole 1% cream applied twice daily

Clotrimazole 1% cream applied twice daily is a safe, effective first-line topical azole for interdigital tinea pedis, including in diabetic patients without contraindications.