,Question 1: A 45-year-old female presents with a scaly, erythematous plaque on her elbow that is well-
demarcated and has a silvery scale. She reports that the lesions are pruritic and worsen during the winter
months. What is the most likely diagnosis?
A) Eczema (atopic dermatitis)
B) Psoriasis
C) Tinea corporis
D) Contact dermatitis
Answer: B
Psoriasis is characterized by well-demarcated, erythematous plaques with silvery scales, commonly
affecting extensor surfaces (elbows, knees) and the scalp. It often has a chronic relapsing course with
exacerbations in winter. Eczema is more commonly flexural; tinea corporis has an annular appearance
with central clearing; contact dermatitis is often localized to the area of exposure.
Question 2: A 32-year-old male presents with a rash on his trunk that began as a single "herald patch"
followed by multiple smaller lesions distributed in a "Christmas tree" pattern along the skin lines. He
reports mild pruritus. What is the most likely diagnosis?
A) Tinea versicolor
B) Pityriasis rosea
C) Secondary syphilis
D) Guttate psoriasis
Answer: B
Pityriasis rosea typically begins with a solitary herald patch followed by a generalized eruption of
smaller lesions in a Christmas tree pattern along Langer's lines. It is self-limiting and often resolves in 6-
8 weeks. Tinea versicolor presents with hypo- or hyperpigmented macules; secondary syphilis has
palmar-plantar involvement; guttate psoriasis presents with small drop-like lesions.
Question 3: A 68-year-old male with a history of extensive sun exposure presents with a pearly,
translucent nodule on his nose with telangiectasia and a rolled border. What is the most likely diagnosis?
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,A) Squamous cell carcinoma
B) Basal cell carcinoma
C) Melanoma
D) Actinic keratosis
Answer: B
Basal cell carcinoma (BCC) is the most common skin cancer, presenting as a pearly, translucent nodule
with telangiectasia and a rolled border on sun-exposed areas. Squamous cell carcinoma is scaly and
crusted; melanoma has asymmetry, irregular borders, and color variation; actinic keratosis is a
precancerous scaly lesion.
Question 4: A 55-year-old female presents with a pruritic vesicular rash on her wrists, forearms, and
buttocks. She reports that her sister has a similar rash. What is the most likely diagnosis?
A) Contact dermatitis
B) Scabies
C) Atopic dermatitis
D) Dermatitis herpetiformis
Answer: B
Scabies presents with intense pruritus (worse at night) and vesicular lesions in characteristic locations:
interdigital spaces, wrists, elbows, and buttocks. It is highly contagious and often affects multiple family
members. Contact dermatitis is localized to the area of exposure; atopic dermatitis is flexural; dermatitis
herpetiformis is associated with celiac disease.
Question 5: A 28-year-old female presents with a circular, erythematous lesion on her forearm with
central clearing and an active border. She has a cat at home. What is the most likely diagnosis?
A) Erythema migrans (Lyme disease)
B) Tinea corporis (ringworm)
C) Granuloma annulare
D) Nummular eczema
Answer: B
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, Tinea corporis (ringworm) presents as an annular lesion with central clearing and an active, scaly
border. It is caused by dermatophyte fungi and is often associated with contact with animals. Erythema
migrans of Lyme disease may have a similar appearance but is typically associated with tick exposure
and may have a "bull's-eye" appearance; granuloma annulare is non-scaly; nummular eczema is coin-
shaped and pruritic.
Question 6: A 72-year-old male with a history of actinic keratosis presents with a tender, erythematous,
crusted nodule on his bald scalp that has been growing over the past 2 months. What is the most likely
diagnosis?
A) Basal cell carcinoma
B) Squamous cell carcinoma
C) Seborrheic keratosis
D) Actinic keratosis
Answer: B
Squamous cell carcinoma (SCC) often arises from actinic keratosis on sun-exposed areas and presents as
a tender, erythematous, crusted or scaly nodule. It is more aggressive than BCC and has a higher risk of
metastasis. Seborrheic keratosis is a benign, waxy, "stuck-on" lesion; actinic keratosis is a precancerous
scaly lesion.
Question 7: A 35-year-old female presents with a pruritic, erythematous rash in the flexural areas of her
elbows and knees. She has a history of asthma and allergic rhinitis. What is the most likely diagnosis?
A) Psoriasis
B) Atopic dermatitis (eczema)
C) Contact dermatitis
D) Seborrheic dermatitis
Answer: B
Atopic dermatitis (eczema) is associated with the "atopic triad" (asthma, allergic rhinitis, eczema) and
presents with pruritic, erythematous, scaly lesions in flexural areas. Psoriasis affects extensor surfaces;
contact dermatitis is localized; seborrheic dermatitis affects sebaceous areas (scalp, face, chest).
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