Evidence-Based NP Dermatology Assessment:150
Q&A, Rationales.
2025/2026
1. A 35-year-old woman presents with red, scaly plaques on her
elbows and knees. She reports mild itching. What is the most
likely diagnosis?
Psoriasis
Rationale: Psoriasis commonly presents as well-demarcated,
erythematous plaques with silvery scales on extensor surfaces
such as elbows and knees.
2. A patient presents with tense blisters on the skin and mucous
membranes. Direct immunofluorescence shows IgG deposits
along the basement membrane. What is the most likely diagnosis?
Bullous pemphigoid
Rationale: Bullous pemphigoid is characterized by subepidermal
blisters with IgG deposition along the basement membrane and
typically affects elderly patients.
3. A 22-year-old college student presents with multiple small, pearly
papules on the face with central umbilication. What is the most
likely cause?
Molluscum contagiosum (poxvirus)
Rationale: Molluscum contagiosum presents as small, firm,
pearly papules with central umbilication and is caused by a
poxvirus, commonly seen in young adults and children.
4. A 28-year-old male presents with erythematous, target-shaped
lesions on his hands and feet after a recent herpes simplex
outbreak. What is the most likely diagnosis?
, Erythema multiforme
Rationale: Erythema multiforme often presents with target
lesions on acral surfaces and is commonly triggered by infections
like herpes simplex virus.
5. A patient presents with a well-demarcated, circular area of hair
loss on the scalp. The hair is broken close to the scalp, and there
are no signs of inflammation. What is the most likely diagnosis?
Alopecia areata
Rationale: Alopecia areata is an autoimmune condition causing
patchy, non-scarring hair loss with exclamation mark hairs and
no significant inflammation.
6. A 40-year-old patient presents with a sudden onset of pruritic
wheals that appear and disappear within hours. What is the most
appropriate treatment?
Oral antihistamines
Rationale: Acute urticaria presents as transient, pruritic wheals
and is commonly treated with non-sedating oral antihistamines.
7. A child presents with vesicular lesions on the palms, soles, and
oral mucosa. The lesions are small, red, and painful. What is the
most likely diagnosis?
Hand, foot, and mouth disease
Rationale: Hand, foot, and mouth disease is a viral illness caused
by coxsackievirus, characterized by vesicles on palms, soles, and
oral mucosa, typically in children.
8. A patient presents with thickened, hyperpigmented skin in the
axilla and neck folds. The patient has a BMI of 32. What is the
most likely underlying condition?
Insulin resistance / Acanthosis nigricans
Rationale: Acanthosis nigricans manifests as velvety,
, hyperpigmented plaques in intertriginous areas and is often
associated with insulin resistance or obesity.
9. A 50-year-old man presents with a pearly nodule with
telangiectasias on the nose. What is the most likely diagnosis?
Basal cell carcinoma
Rationale: Basal cell carcinoma typically presents as a pearly,
translucent nodule with telangiectasias, commonly on sun-
exposed areas.
10. A patient presents with sudden, painful, erythematous
nodules on the anterior legs. There is no ulceration. What is the
most likely diagnosis?
Erythema nodosum
Rationale: Erythema nodosum is characterized by tender,
erythematous nodules on the shins and is often associated with
infections, medications, or systemic disease.
11. A 30-year-old female presents with malar erythema,
photosensitivity, and joint pain. ANA is positive. What is the most
likely diagnosis?
Systemic lupus erythematosus (SLE)
Rationale: SLE commonly presents with malar rash,
photosensitivity, arthralgias, and positive ANA.
12. A patient presents with honey-colored crusted lesions
around the mouth and nose. What is the most likely causative
organism?
Staphylococcus aureus / Streptococcus pyogenes (impetigo)
Rationale: Impetigo often presents with golden crusts around
the face, caused primarily by S. aureus or group A Streptococcus.
, 13. A 65-year-old patient presents with a rapidly growing,
irregular, pigmented lesion on the back. What is the most
concerning diagnosis?
Melanoma
Rationale: Melanoma presents as a rapidly enlarging,
asymmetrical, irregularly bordered pigmented lesion, often on
sun-exposed skin.
14. A patient presents with annular, scaly lesions with central
clearing on the trunk. KOH prep shows hyphae. What is the most
likely diagnosis?
Tinea corporis (ringworm)
Rationale: Tinea corporis presents as ring-shaped, scaly lesions
with central clearing and is confirmed by KOH preparation
showing fungal hyphae.
15. A patient presents with grouped vesicles on an
erythematous base along a dermatome. What is the most likely
diagnosis?
Herpes zoster (shingles)
Rationale: Herpes zoster presents with unilateral, dermatomal
vesicular eruptions caused by reactivation of varicella-zoster
virus.
16. A patient presents with sudden hair loss after a stressful
event. The scalp shows diffuse thinning without scarring. What is
the most likely diagnosis?
Telogen effluvium
Rationale: Telogen effluvium is diffuse, non-scarring hair
shedding often triggered by stress, illness, or medications.
17. A patient presents with chronic, itchy, lichenified plaques on
the flexural surfaces of the arms and legs. What is the most likely
Q&A, Rationales.
2025/2026
1. A 35-year-old woman presents with red, scaly plaques on her
elbows and knees. She reports mild itching. What is the most
likely diagnosis?
Psoriasis
Rationale: Psoriasis commonly presents as well-demarcated,
erythematous plaques with silvery scales on extensor surfaces
such as elbows and knees.
2. A patient presents with tense blisters on the skin and mucous
membranes. Direct immunofluorescence shows IgG deposits
along the basement membrane. What is the most likely diagnosis?
Bullous pemphigoid
Rationale: Bullous pemphigoid is characterized by subepidermal
blisters with IgG deposition along the basement membrane and
typically affects elderly patients.
3. A 22-year-old college student presents with multiple small, pearly
papules on the face with central umbilication. What is the most
likely cause?
Molluscum contagiosum (poxvirus)
Rationale: Molluscum contagiosum presents as small, firm,
pearly papules with central umbilication and is caused by a
poxvirus, commonly seen in young adults and children.
4. A 28-year-old male presents with erythematous, target-shaped
lesions on his hands and feet after a recent herpes simplex
outbreak. What is the most likely diagnosis?
, Erythema multiforme
Rationale: Erythema multiforme often presents with target
lesions on acral surfaces and is commonly triggered by infections
like herpes simplex virus.
5. A patient presents with a well-demarcated, circular area of hair
loss on the scalp. The hair is broken close to the scalp, and there
are no signs of inflammation. What is the most likely diagnosis?
Alopecia areata
Rationale: Alopecia areata is an autoimmune condition causing
patchy, non-scarring hair loss with exclamation mark hairs and
no significant inflammation.
6. A 40-year-old patient presents with a sudden onset of pruritic
wheals that appear and disappear within hours. What is the most
appropriate treatment?
Oral antihistamines
Rationale: Acute urticaria presents as transient, pruritic wheals
and is commonly treated with non-sedating oral antihistamines.
7. A child presents with vesicular lesions on the palms, soles, and
oral mucosa. The lesions are small, red, and painful. What is the
most likely diagnosis?
Hand, foot, and mouth disease
Rationale: Hand, foot, and mouth disease is a viral illness caused
by coxsackievirus, characterized by vesicles on palms, soles, and
oral mucosa, typically in children.
8. A patient presents with thickened, hyperpigmented skin in the
axilla and neck folds. The patient has a BMI of 32. What is the
most likely underlying condition?
Insulin resistance / Acanthosis nigricans
Rationale: Acanthosis nigricans manifests as velvety,
, hyperpigmented plaques in intertriginous areas and is often
associated with insulin resistance or obesity.
9. A 50-year-old man presents with a pearly nodule with
telangiectasias on the nose. What is the most likely diagnosis?
Basal cell carcinoma
Rationale: Basal cell carcinoma typically presents as a pearly,
translucent nodule with telangiectasias, commonly on sun-
exposed areas.
10. A patient presents with sudden, painful, erythematous
nodules on the anterior legs. There is no ulceration. What is the
most likely diagnosis?
Erythema nodosum
Rationale: Erythema nodosum is characterized by tender,
erythematous nodules on the shins and is often associated with
infections, medications, or systemic disease.
11. A 30-year-old female presents with malar erythema,
photosensitivity, and joint pain. ANA is positive. What is the most
likely diagnosis?
Systemic lupus erythematosus (SLE)
Rationale: SLE commonly presents with malar rash,
photosensitivity, arthralgias, and positive ANA.
12. A patient presents with honey-colored crusted lesions
around the mouth and nose. What is the most likely causative
organism?
Staphylococcus aureus / Streptococcus pyogenes (impetigo)
Rationale: Impetigo often presents with golden crusts around
the face, caused primarily by S. aureus or group A Streptococcus.
, 13. A 65-year-old patient presents with a rapidly growing,
irregular, pigmented lesion on the back. What is the most
concerning diagnosis?
Melanoma
Rationale: Melanoma presents as a rapidly enlarging,
asymmetrical, irregularly bordered pigmented lesion, often on
sun-exposed skin.
14. A patient presents with annular, scaly lesions with central
clearing on the trunk. KOH prep shows hyphae. What is the most
likely diagnosis?
Tinea corporis (ringworm)
Rationale: Tinea corporis presents as ring-shaped, scaly lesions
with central clearing and is confirmed by KOH preparation
showing fungal hyphae.
15. A patient presents with grouped vesicles on an
erythematous base along a dermatome. What is the most likely
diagnosis?
Herpes zoster (shingles)
Rationale: Herpes zoster presents with unilateral, dermatomal
vesicular eruptions caused by reactivation of varicella-zoster
virus.
16. A patient presents with sudden hair loss after a stressful
event. The scalp shows diffuse thinning without scarring. What is
the most likely diagnosis?
Telogen effluvium
Rationale: Telogen effluvium is diffuse, non-scarring hair
shedding often triggered by stress, illness, or medications.
17. A patient presents with chronic, itchy, lichenified plaques on
the flexural surfaces of the arms and legs. What is the most likely
