Dermatologist Certificate Skin Disorders and Diagnosis 3

Question 1

Which mite is responsible for scabies infestation?

Accepted Answer

Sarcoptes scabiei var. hominis

Answer

Scabies is caused by the human itch mite Sarcoptes scabiei var. hominis, which burrows into the stratum corneum causing intense pruritus, especially at night.

Question 2

Koebner phenomenon — appearance of lesions along lines of trauma — is classically seen in which condition?

Accepted Answer

Psoriasis

Answer

The Koebner (isomorphic) phenomenon, where new psoriatic plaques develop at sites of skin trauma or injury, is a hallmark feature of psoriasis.

Question 3

What histological finding is characteristic of mycosis fungoides (cutaneous T-cell lymphoma)?

Accepted Answer

Pautrier microabscesses with atypical lymphocytes in the epidermis

Answer

Pautrier microabscesses — collections of atypical cerebriform T-lymphocytes within the epidermis — are pathognomonic of mycosis fungoides on histology.

Question 4

Livedo reticularis presenting with systemic thrombosis and recurrent pregnancy loss suggests which underlying condition?

Accepted Answer

Antiphospholipid syndrome

Answer

The combination of livedo reticularis, arterial or venous thrombosis, and recurrent pregnancy loss is the classic triad of antiphospholipid antibody syndrome.

Question 5

Which skin finding is pathognomonic for Lyme disease?

Accepted Answer

Erythema migrans — expanding annular erythema at tick bite site

Answer

Erythema migrans, the expanding bull's-eye or ring-shaped rash at the site of Borrelia burgdorferi-infected tick bite, is pathognomonic for early Lyme disease.

Dermatologist Certificate Practice Test

Dermatologist Certificate Practice Test

Dermatologist Certificate Skin Disorders and Diagnosis 3