NR511 Differential Diagnosis & Primary Care Practicum Midterm Exam Questions
1–100 Questions with Correct DETAILED ANSWERs and Explanations
Domain 1: Dermatology
1. A 22-year-old college student presents with an erythematous, scaling rash on
the scalp, eyebrows, and nasolabial folds. The rash is greasy and pruritic. What is
the MOST likely diagnosis?
A) Atopic dermatitis
B) Psoriasis
C) Seborrheic dermatitis
D) Contact dermatitis
Correct Answer: C) Seborrheic dermatitis
Explanation: Seborrheic dermatitis is a chronic inflammatory condition affecting areas
rich in sebaceous glands (scalp, face, chest, and intertriginous areas). The classic
presentation includes erythematous, greasy scales on the scalp (dandruff), eyebrows,
nasolabial folds, and behind the ears. It is thought to be related to Malassezia yeast
overgrowth. Atopic dermatitis typically affects flexural areas (antecubital/popliteal
fossae) and presents with dry, pruritic skin, not greasy scales. Psoriasis presents with
well-demarcated, silvery-white scales on extensor surfaces. Contact dermatitis presents
with erythema, edema, and vesicles in a localized pattern consistent with exposure.
2. A patient presents with a pruritic rash characterized by erythematous papules
and vesicles in a linear arrangement on the arms and legs. The patient recently
returned from a hiking trip. What is the MOST likely cause of this eruption?
A) Scabies
B) Urticaria
,C) Allergic contact dermatitis from poison ivy
D) Herpes zoster
Correct Answer: C) Allergic contact dermatitis from poison ivy
Explanation: The linear arrangement of papules and vesicles in a patient who recently
hiked is classic for allergic contact dermatitis caused by poison ivy, oak, or sumac
(urushiol). The rash typically appears 24-72 hours after exposure. The linear pattern
results from the plant brushing against the skin or the patient scratching and spreading
the resin. Scabies (A) typically presents as burrows in web spaces, wrists, and axillae, with
intense nocturnal pruritus. Urticaria (B) presents as transient, well-circumscribed wheals,
not vesicular linear rashes. Herpes zoster (D) presents as a dermatomal, unilateral
vesicular eruption, often with prodromal pain.
3. A 45-year-old fair-skinned female presents with a pearly, translucent papule
with telangiectasias and a rolled, ulcerated center on the nose. The lesion has been
slowly growing over the past year and occasionally bleeds. What is the MOST
likely diagnosis?
A) Squamous cell carcinoma
B) Malignant melanoma
C) Actinic keratosis
D) Basal cell carcinoma
Correct Answer: D) Basal cell carcinoma
Explanation: This is the classic description of nodular basal cell carcinoma (BCC)—a
pearly, waxy, translucent papule with overlying telangiectasias, central ulceration (rodent
ulcer), and a rolled border. BCC is the most common skin cancer, most frequently
occurring on sun-exposed areas (nose, face). It is locally invasive but rarely metastasizes.
Squamous cell carcinoma (A) typically presents as a firm, erythematous, hyperkeratotic
papule or plaque that may crust or ulcerate. Malignant melanoma (B) uses the ABCDE
criteria (Asymmetry, Border irregularity, Color variation, Diameter >6mm, Evolution).
Actinic keratosis (C) is a rough, scaly, erythematous macule/papule in sun-exposed
areas.
, 4. A 30-year-old female presents with a complaint of "bumps on my legs after
shaving." Examination reveals multiple small, erythematous follicular papules and
pustules on the anterior lower legs. The surrounding skin is otherwise normal.
What is the MOST appropriate initial treatment?
A) Oral cephalexin 500 mg BID for 7 days
B) Topical corticosteroid cream applied BID
C) Discontinuation of shaving, warm compresses, and topical benzoyl peroxide wash
D) Referral to dermatology for photodynamic therapy
Correct Answer: C) Discontinuation of shaving, warm compresses, and topical
benzoyl peroxide wash
Explanation: This presentation is consistent with folliculitis, an inflammation or infection
of the hair follicles, commonly triggered by shaving (pseudofolliculitis barbae when on
the face/neck). Mild, superficial cases respond well to conservative measures:
discontinuing the irritant (shaving), warm compresses, and over-the-counter
antibacterial washes (benzoyl peroxide). Oral antibiotics (A) are reserved for more
extensive, deep, or recurrent infections (furunculosis/carbuncles). Topical corticosteroids
(B) are not indicated for a bacterial folliculitis and could worsen infection. Referral to
dermatology (D) is unnecessary for a mild, uncomplicated initial presentation.
5. A patient presents with a tender, erythematous, warm, indurated plaque with
poorly demarcated borders on the lower extremity. The area is edematous, and
there is no fluctuance. Vital signs include temperature 101.2°F and HR 98. What is
the MOST likely diagnosis?
A) Impetigo
B) Cellulitis
C) Erysipelas
D) Deep vein thrombosis
Correct Answer: B) Cellulitis
Explanation: Cellulitis is a diffuse, acute infection of the dermis and subcutaneous
tissue, typically caused by Streptococcus pyogenes or Staphylococcus aureus. Key
features include erythema, warmth, edema, tenderness, induration, and poorly
demarcated borders. Systemic symptoms (fever, tachycardia) are common. Erysipelas (C)
is a more superficial infection with sharply demarcated, raised borders and prominent
1–100 Questions with Correct DETAILED ANSWERs and Explanations
Domain 1: Dermatology
1. A 22-year-old college student presents with an erythematous, scaling rash on
the scalp, eyebrows, and nasolabial folds. The rash is greasy and pruritic. What is
the MOST likely diagnosis?
A) Atopic dermatitis
B) Psoriasis
C) Seborrheic dermatitis
D) Contact dermatitis
Correct Answer: C) Seborrheic dermatitis
Explanation: Seborrheic dermatitis is a chronic inflammatory condition affecting areas
rich in sebaceous glands (scalp, face, chest, and intertriginous areas). The classic
presentation includes erythematous, greasy scales on the scalp (dandruff), eyebrows,
nasolabial folds, and behind the ears. It is thought to be related to Malassezia yeast
overgrowth. Atopic dermatitis typically affects flexural areas (antecubital/popliteal
fossae) and presents with dry, pruritic skin, not greasy scales. Psoriasis presents with
well-demarcated, silvery-white scales on extensor surfaces. Contact dermatitis presents
with erythema, edema, and vesicles in a localized pattern consistent with exposure.
2. A patient presents with a pruritic rash characterized by erythematous papules
and vesicles in a linear arrangement on the arms and legs. The patient recently
returned from a hiking trip. What is the MOST likely cause of this eruption?
A) Scabies
B) Urticaria
,C) Allergic contact dermatitis from poison ivy
D) Herpes zoster
Correct Answer: C) Allergic contact dermatitis from poison ivy
Explanation: The linear arrangement of papules and vesicles in a patient who recently
hiked is classic for allergic contact dermatitis caused by poison ivy, oak, or sumac
(urushiol). The rash typically appears 24-72 hours after exposure. The linear pattern
results from the plant brushing against the skin or the patient scratching and spreading
the resin. Scabies (A) typically presents as burrows in web spaces, wrists, and axillae, with
intense nocturnal pruritus. Urticaria (B) presents as transient, well-circumscribed wheals,
not vesicular linear rashes. Herpes zoster (D) presents as a dermatomal, unilateral
vesicular eruption, often with prodromal pain.
3. A 45-year-old fair-skinned female presents with a pearly, translucent papule
with telangiectasias and a rolled, ulcerated center on the nose. The lesion has been
slowly growing over the past year and occasionally bleeds. What is the MOST
likely diagnosis?
A) Squamous cell carcinoma
B) Malignant melanoma
C) Actinic keratosis
D) Basal cell carcinoma
Correct Answer: D) Basal cell carcinoma
Explanation: This is the classic description of nodular basal cell carcinoma (BCC)—a
pearly, waxy, translucent papule with overlying telangiectasias, central ulceration (rodent
ulcer), and a rolled border. BCC is the most common skin cancer, most frequently
occurring on sun-exposed areas (nose, face). It is locally invasive but rarely metastasizes.
Squamous cell carcinoma (A) typically presents as a firm, erythematous, hyperkeratotic
papule or plaque that may crust or ulcerate. Malignant melanoma (B) uses the ABCDE
criteria (Asymmetry, Border irregularity, Color variation, Diameter >6mm, Evolution).
Actinic keratosis (C) is a rough, scaly, erythematous macule/papule in sun-exposed
areas.
, 4. A 30-year-old female presents with a complaint of "bumps on my legs after
shaving." Examination reveals multiple small, erythematous follicular papules and
pustules on the anterior lower legs. The surrounding skin is otherwise normal.
What is the MOST appropriate initial treatment?
A) Oral cephalexin 500 mg BID for 7 days
B) Topical corticosteroid cream applied BID
C) Discontinuation of shaving, warm compresses, and topical benzoyl peroxide wash
D) Referral to dermatology for photodynamic therapy
Correct Answer: C) Discontinuation of shaving, warm compresses, and topical
benzoyl peroxide wash
Explanation: This presentation is consistent with folliculitis, an inflammation or infection
of the hair follicles, commonly triggered by shaving (pseudofolliculitis barbae when on
the face/neck). Mild, superficial cases respond well to conservative measures:
discontinuing the irritant (shaving), warm compresses, and over-the-counter
antibacterial washes (benzoyl peroxide). Oral antibiotics (A) are reserved for more
extensive, deep, or recurrent infections (furunculosis/carbuncles). Topical corticosteroids
(B) are not indicated for a bacterial folliculitis and could worsen infection. Referral to
dermatology (D) is unnecessary for a mild, uncomplicated initial presentation.
5. A patient presents with a tender, erythematous, warm, indurated plaque with
poorly demarcated borders on the lower extremity. The area is edematous, and
there is no fluctuance. Vital signs include temperature 101.2°F and HR 98. What is
the MOST likely diagnosis?
A) Impetigo
B) Cellulitis
C) Erysipelas
D) Deep vein thrombosis
Correct Answer: B) Cellulitis
Explanation: Cellulitis is a diffuse, acute infection of the dermis and subcutaneous
tissue, typically caused by Streptococcus pyogenes or Staphylococcus aureus. Key
features include erythema, warmth, edema, tenderness, induration, and poorly
demarcated borders. Systemic symptoms (fever, tachycardia) are common. Erysipelas (C)
is a more superficial infection with sharply demarcated, raised borders and prominent
