DNCB-DNC MCQs
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DNCB-DNC Exam Questions
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DNCB Dermatology Nurse Certified - 2026
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A patient presents with thickened skin and impaired barrier function. Histology reveals abnormal keratinocyte differentiation. Which epidermal layer is most likely dysfunctional?
Stratum basale
Stratum spinosum
Stratum granulosum
Stratum corneum
Answer: D
Explanation: The stratum corneum forms the primary barrier via keratinized cells. Dysfunction causes barrier defects and thickening
A nurse measures transepidermal water loss (TEWL) in a patient using a vapometer. Normal TEWL is 10 g/m??/h. The patient???s reading is 35 g/m??/h. Which structural component is most compromised?
Lamellar bodies in stratum granulosum
Collagen in papillary dermis
Sebum from sebaceous glands
Eccrine sweat glands
Answer: A
Explanation: Lamellar bodies secrete lipids that form the permeability barrier. Elevated TEWL indicates defective lipid matrix in the stratum granulosum
Refer to the diagram of a hair follicle below:
[Roo Bulb] ??? [Is hmus] ??? [Infundibulum]
A patient has hair loss localized to the isthmus region. Which phase of the hair cycle is disrupted?
Anagen
Catagen
Telogen
Exogen
Answer: B
Explanation: The isthmus marks the regression zone during catagen, where follicular degeneration
occurs
A patient with burns has impaired thermoregulation. Calculation shows a 40% reduction in evaporative cooling. Which gland type is primarily affected?
Apocrine
Sebaceous
Eccrine
Mammary
Answer: C
Explanation: Eccrine glands produce sweat for evaporative cooling. Reduced function directly impairs thermoregulation
A formula for vitamin D synthesis is:
UVB
7-dehydrocholesterol
Previtamin D3
Which epidermal cell type initiates this process?
Langerhans cell
Melanocyte
Keratinocyte
Merkel cell
Answer: C
Explanation: Keratinocytes contain 7-dehydrocholesterol and convert it to previtamin D??? under UVB
A biopsy shows fragmented elastin fibers in the reticular dermis. Which mechanical property is most compromised?
Tensile strength
Barrier integrity
Elastic recoil
Adhesion
Answer: C
Explanation: Elastin enables skin recoil after stretching. Fragmentation reduces elasticity
A patient has subcutaneous fat necrosis. Using the formula:
Insulation (clo) = 0.08 ?? fat thickness (mm)
If fat thickness decreases from 20mm to 5mm, insulation drops by:
0.4 clo
1.2 clo
1.6 clo
2.0 clo
Answer: B
Explanation: Initial insulation = 0.08 ?? 20 = 1.6 clo. Post-reduction = 0.08 ?? 5 = 0.4 clo. Difference = 1.2 clo
A diagram shows a nail unit:
Ma rix ??? Nail Pla e ??? Hyponychium
Damage to the matrix would directly affect:
Nail plate adhesion
Nail growth rate
Cuticle integrity
Lunula visibility
Answer: B
Explanation: The matrix produces nail plate cells; damage slows growth
A patient has defective sebum production (normal = 2 mg/cm??/day). Sebum???s pH is typically:
A. 3.5???4.5
B. 5.0???6.5
C. 7.0???7.4
D. 8.0???8.5
Answer: B
Explanation: Sebum maintains skin pH at 5.0???6.5, critical for antimicrobial defense
A nurse assesses a pressure injury. The dermal papillae are flattened. Which sensation is most
diminished?
Vibration
Light touch
Pain
Temperature
Answer: B
Explanation: Meissner???s corpuscles in dermal papillae detect light touch. Flattening reduces sensitivity
A burn patient lacks stratum corneum. Which function is immediately compromised?
Vitamin D synthesis
Thermosensation
Pathogen barrier
Hair growth
Answer: C
Explanation: The stratum corneum is the primary physical barrier against pathogens
Refer to a sweat gland diagram:
Coiled Secre ory Uni ??? uc ??? Skin Surface
Blockage at the duct would cause:
Reduced sebum production
Miliaria crystallina
Hyperkeratosis
Alopecia
Answer: B
Explanation: Duct obstruction traps sweat, causing miliaria (heat rash)
A patient has a collagen disorder. Collagen constitutes approximately what percentage of the dermis by dry weight?
25%
50%
75%
90%
Answer: C
Explanation: Collagen makes up ~75% of the dermis??? dry weight, providing tensile strength
A formula for skin regeneration is:
Healing rate =
Total epidermal cells
Cell cycle time
If cell cycle time increases from 30 to 60 hours, healing rate:
Doubles
Halves
Remains unchanged
Quadruples
Answer: B
Explanation: Healing rate is inversely proportional to cell cycle time. Doubling cycle time halves healing
A patient has no Merkel cells. Which sensation is most affected?
Pressure
Itch
Static touch
Vibration
Answer: C
Explanation: Merkel cells detect static touch and texture
A nurse calculates body surface area (BSA. using the Mosteller formula:
BSA =
Height (cm)??Weight (kg) 3600
For a patient (height 170 cm, weight 70 kg), BSA is:
1.73 m??
1.85 m??
1.92 m??
2.05 m??
Answer: A
3600
Explanation: BSA = 170??70
=
11900
3600
= 3.305 ??? 1.73 m??
A diagram shows a sebaceous gland draining into a hair follicle. Blockage would cause:
Anhidrosis
Comedone formation
Telogen effluvium
Onycholysis
Answer: B
Explanation: Sebaceous glands secrete sebum into follicles. Blockage forms comedones (blackheads/whiteheads)
A patient has impaired apocrine glands. Which function is unaffected?
Thermoregulation
Pheromone release
Axillary odor
Emotional sweating
Answer: A
Explanation: Apocrine glands contribute to odor/pheromones but not thermoregulation (eccrine function)
Using the rule of nines for burns, a patient with full-thickness burns on the entire left arm has:
4.5% BSA
9% BSA
13.5% BSA
18% BSA
Answer: B
Explanation: Each arm represents 9% BSA (4.5% anterior, 4.5% posterior)
A patient lacks subcutaneous fat. Which parameter decreases?
Skin pH
Vitamin D synthesis
Insulative capacity
Barrier function
Answer: C
Explanation: Subcutaneous fat provides insulation against heat loss
Refer to a cross-section of the epidermis:
S ra um Basale ??? S ra um Spinosum ??? S ra um Granulosum ??? S ra um Corneum
A drug targets rapidly dividing cells. Which layer is affected?
Stratum basale
Stratum spinosum
Stratum granulosum
Stratum corneum
Answer: A
Explanation: Stratum basale contains mitotically active stem cells
A patient has hypohidrosis. The nurse measures sweat production at 15 ml/m??/hr (normal: 30???120 ml/m??/hr). Which gland is deficient?
Sebaceous
Apocrine
Eccrine
Meibomian
Answer: C
Explanation: Eccrine glands produce thermoregulatory sweat. Hypohidrosis indicates eccrine dysfunction
A formula for skin protection is:
SPF =
UV dose with protection
UV dose without protection
If SPF 30 blocks 96.7% of UVB, the transmitted UVB is:
A. 0.33%
3.3%
33%
66%
Answer: B
Explanation: SPF 30 blocks 96.7% UVB, so transmitted UVB = 100% ??? 96.7% = 3.3%
A patient has onychomycosis. Which nail structure is invaded by fungi?
Nail bed
Lunula
Cuticle
Hyponychium
Answer: A
Explanation: Fungal infections primarily invade the nail bed (ventral layer)
A nurse uses a dermatoscope. Which dermal feature is visualized?
Papillary ridges
Subcutaneous fat
Arrector pili muscle
Eccrine duct
Answer: A
Explanation: Dermatoscopy visualizes papillary ridges (fingerprints) in the dermoepidermal junction
A patient has defective melanocytes. Which radiation type is most harmful?
UVA
UVB
UVC
Infrared
Answer: B
Explanation: Melanin absorbs UVB. Defective melanocytes increase UVB-induced DNA damage
A diagram shows a hair follicle with attached arrector pili muscle. Contraction causes:
Sebum release
Goosebumps
Sweat secretion
Vasodilation
Answer: B
Explanation: Arrector pili contraction erects hairs, causing piloerection (goosebumps)
A nurse calculates epidermal turnover time. If basal cell division rate is 0.5/day and epidermal thickness is 0.1 mm, turnover time is:
14 days
28 days
42 days
56 days
Answer: B
Explanation: Turnover time = epidermal thickness / division rate. Standard is 28 days
A patient has no Langerhans cells. Which immune response is impaired?
Antibody production
Complement activation
Antigen presentation
Neutrophil chemotaxis
Answer: C
Explanation: Langerhans cells are epidermal antigen-presenting cells
Refer to a schematic of skin layers:
Epidermis (0.1 mm) ??? ermis (2 mm) ??? Subcu is (10 mm)
A drug with log P = 3.5 is applied. Where does it accumulate?
Epidermis
Dermis
Subcutis
All equally
Answer: C
Explanation: High log P (lipophilicity) favors partitioning into subcutaneous fat
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