MD MD - Doctor of Medicine Dermatology and Skin Disorders Questions and Answers 2 — Questions and Answers
Question 1: Acne vulgaris is primarily caused by which organism?
- Staphylococcus aureus
- Cutibacterium acnes (Correct answer)
- Streptococcus pyogenes
- Malassezia furfur
Correct answer: Cutibacterium acnes
Acne vulgaris is primarily caused by Cutibacterium acnes (formerly Propionibacterium acnes), which colonizes hair follicles in sebum-rich areas.
Question 2: Which topical agent is considered first-line for mild-to-moderate acne vulgaris?
- Isotretinoin
- Oral tetracycline
- Benzoyl peroxide (Correct answer)
- Triamcinolone
Correct answer: Benzoyl peroxide
Benzoyl peroxide is first-line topical treatment for mild-to-moderate acne due to its antibacterial, keratolytic, and comedolytic properties.
Question 3: Tinea versicolor (pityriasis versicolor) is caused by which organism?
- Candida albicans
- Trichophyton rubrum
- Epidermophyton floccosum
- Malassezia furfur (Correct answer)
Correct answer: Malassezia furfur
Tinea versicolor is caused by Malassezia furfur, a lipophilic dimorphic yeast that normally colonizes the skin's stratum corneum.
Question 4: Allergic contact dermatitis is a type IV hypersensitivity reaction mediated by:
- IgE antibodies and mast cells
- T lymphocytes (delayed-type) (Correct answer)
- IgG antibodies and complement
- Neutrophil infiltration
Correct answer: T lymphocytes (delayed-type)
Allergic contact dermatitis is a type IV (cell-mediated/delayed-type) hypersensitivity reaction mediated by sensitized T lymphocytes.
Question 5: Which classic description applies to varicella (chickenpox) skin lesions?
- Honey-colored crusted vesicles
- Dew drops on a rose petal (Correct answer)
- Target lesions with central clearing
- Silvery-scaled papules on elbows
Correct answer: Dew drops on a rose petal
Varicella lesions are classically described as 'dew drops on a rose petal' — clear vesicles on an erythematous base at various stages of evolution.
Question 6: First-line topical treatment for scabies in adults is:
- Lindane 1% lotion
- Permethrin 5% cream (Correct answer)
- Benzyl benzoate 25%
- Ivermectin oral
Correct answer: Permethrin 5% cream
Permethrin 5% cream applied to the entire body and left on overnight is the first-line treatment for scabies in adults and children over 2 months.
MD MD - Doctor of Medicine Dermatology and Skin Disorders Questions and Answers 2
Acne vulgaris is primarily caused by which organism?