Dermatology Prometric exam questions with answers

1. Question 1Basic Science, Skin Biology, Cutaneous Immunology and Dermatopathologyeasy

   Birbeck granules seen on electron microscopy are characteristic of which cell found in the epidermis?

   1. AMelanocyte
   2. BGranular layer keratinocyte
   3. CLangerhans cell
   4. DMerkel cell
   Show answer and explanation▾

   Answer: C. Langerhans cell

   Langerhans cells are bone marrow-derived antigen-presenting dendritic cells, mainly in the stratum spinosum, and contain racket-shaped Birbeck granules associated with langerin (CD207); they also express CD1a. Merkel cells are mechanoreceptor cells containing dense-core neurosecretory granules. Melanocytes contain melanosomes, and granular layer keratinocytes contain keratohyalin and lamellar granules.

2. Question 2Papulosquamous and Eczematous Dermatosesmedium

   A 26-year-old man has a 2-week history of oval, scaly pink plaques on the trunk aligned along skin cleavage lines. He also has scaly macules on both palms and soles and generalised lymphadenopathy. Which investigation is most important?

   1. ASkin scraping for fungal microscopy
   2. BSyphilis serology
   3. CAntistreptolysin O titre
   4. DPatch testing to a standard series
   Show answer and explanation▾

   Answer: B. Syphilis serology

   Although the truncal eruption resembles pityriasis rosea, involvement of the palms and soles and generalised lymphadenopathy are atypical and suggest secondary syphilis, which can closely mimic it; syphilis serology is therefore essential in a sexually active adult. Fungal scraping is useful for a single annular plaque but would not explain palmoplantar lesions and lymphadenopathy. Streptococcal serology is relevant to guttate psoriasis.

3. Question 3Papulosquamous and Eczematous Dermatoseseasy

   During patch testing for suspected allergic contact dermatitis, the allergen chambers are removed and read at 48 hours. When should a second reading be performed so that late reactions are not missed?

   1. ANo further reading is needed after the day 2 reading
   2. BAbout 30 minutes after the patches are applied
   3. CAround day 4 (between day 3 and day 5)
   4. DAt 24 hours after the patches are applied
   Show answer and explanation▾

   Answer: C. Around day 4 (between day 3 and day 5)

   Allergic contact dermatitis is a delayed type IV reaction that may take several days to develop, so a second reading at around day 3 to day 5 is standard, with a later reading around day 7 for some allergens such as corticosteroids and some metals. Relying on the day 2 reading alone misses a substantial number of positive reactions. Readings at 30 minutes detect immediate contact urticaria rather than delayed hypersensitivity.

4. Question 4Urticaria, Erythemas, Drug Eruptions, Purpura and Cutaneous Vasculitishard

   Five weeks after starting allopurinol, a 58-year-old man develops fever, a widespread morbilliform eruption, marked facial oedema and cervical lymphadenopathy. Eosinophils are 2.4 x10^9/L and ALT is 410 U/L. The mucous membranes are spared. What is the most likely diagnosis?

   1. ASimple maculopapular drug exanthem
   2. BDrug reaction with eosinophilia and systemic symptoms
   3. CStevens-Johnson syndrome
   4. DAcute generalised exanthematous pustulosis
   Show answer and explanation▾

   Answer: B. Drug reaction with eosinophilia and systemic symptoms

   A latency of 2 to 8 weeks, facial oedema, fever, lymphadenopathy, eosinophilia and hepatitis are characteristic of DRESS, and allopurinol is a common culprit, particularly in HLA-B*58:01 carriers. Stevens-Johnson syndrome usually starts 4 to 28 days after the drug with prominent mucositis and epidermal detachment. AGEP develops within days with sheets of sterile pustules, and a simple exanthem lacks internal organ involvement.

5. Question 5Urticaria, Erythemas, Drug Eruptions, Purpura and Cutaneous Vasculitismedium

   A 35-year-old woman has had itchy wheals on most days for 4 months without identifiable triggers. Standard-dose cetirizine 10 mg daily for 4 weeks has given little relief. What is the next recommended step?

   1. AIncrease the second-generation antihistamine up to four times the standard dose
   2. BStart omalizumab before any change in antihistamine dose
   3. CSwitch to a sedating first-generation antihistamine at night
   4. DStart a long-term course of oral prednisolone
   Show answer and explanation▾

   Answer: A. Increase the second-generation antihistamine up to four times the standard dose

   International urticaria guidelines recommend a standard-dose non-sedating H1 antihistamine first, then up to fourfold updosing if control is inadequate after 2 to 4 weeks, adding omalizumab only if symptoms persist. Long-term systemic corticosteroids are not recommended because of adverse effects; only short courses for exacerbations are acceptable. First-generation antihistamines cause sedation and impaired performance and are not advised.

6. Question 6Vesiculobullous and Autoimmune Blistering Diseasesmedium

   A 30-year-old man has intensely itchy grouped vesicles and excoriations on the elbows, knees and buttocks. Direct immunofluorescence shows granular IgA deposits in the dermal papillae. Before starting dapsone, which test is essential?

   1. AHLA-B*58:01 genotyping
   2. BThiopurine methyltransferase activity
   3. CGlucose-6-phosphate dehydrogenase activity
   4. DSerum total IgE level
   Show answer and explanation▾

   Answer: C. Glucose-6-phosphate dehydrogenase activity

   The findings indicate dermatitis herpetiformis, which responds rapidly to dapsone alongside a strict gluten-free diet. Dapsone causes dose-related haemolysis that is severe in G6PD deficiency, so G6PD activity must be checked first, with monitoring of blood counts and methaemoglobin. TPMT is checked before azathioprine, and HLA-B*58:01 relates to allopurinol hypersensitivity.

7. Question 7Connective Tissue Disease, Dermal, Subcutaneous, Metabolic and Systemic Skin Diseasehard

   A 62-year-old woman has a heliotrope rash, Gottron papules, a photodistributed shawl-pattern erythema and proximal muscle weakness. Myositis serology shows anti-TIF1-gamma antibodies. What is the most important next step?

   1. AEchocardiography to screen for pulmonary hypertension
   2. BSkin biopsy to exclude subacute cutaneous lupus
   3. CComprehensive screening for an underlying malignancy
   4. DHigh-resolution CT for rapidly progressive interstitial lung disease
   Show answer and explanation▾

   Answer: C. Comprehensive screening for an underlying malignancy

   In adults, anti-TIF1-gamma antibodies are strongly associated with cancer-associated dermatomyositis, so thorough malignancy screening (often CT of chest, abdomen and pelvis, with age- and sex-appropriate tests such as mammography and gynaecological assessment) is essential and should be repeated over the following years. Rapidly progressive interstitial lung disease is the hallmark of anti-MDA5 antibodies rather than TIF1-gamma. The clinical features already establish dermatomyositis.

8. Question 8Cutaneous Infections, Infestations, Bites and Sexually Transmitted Infectionseasy

   A 24-year-old woman has intense nocturnal itching for 3 weeks with burrows in the finger webs and on the wrists. Her partner is also itchy. What is the most appropriate management?

   1. AOral cetirizine and a potent topical corticosteroid
   2. BPermethrin 5% cream to the whole body, repeated after 7 days, for her and all close contacts
   3. COral terbinafine for 2 weeks
   4. DPermethrin 5% cream once, to affected areas only, for the patient alone
   Show answer and explanation▾

   Answer: B. Permethrin 5% cream to the whole body, repeated after 7 days, for her and all close contacts

   Scabies is treated with permethrin 5% applied to the whole body from the neck down (including the scalp and face in infants and older people), repeated after 7 days, with simultaneous treatment of all household and sexual contacts and washing of bedding and clothing. Treating only affected areas or only the patient leads to reinfestation. Itch may persist for several weeks after successful treatment.

9. Question 9Cutaneous Infections, Infestations, Bites and Sexually Transmitted Infectionsmedium

   A 70-year-old man has a painful vesicular eruption in the right ophthalmic dermatome that began 2 days ago, including vesicles on the tip of the nose. What is the most appropriate management?

   1. AOral prednisolone alone to prevent post-herpetic neuralgia
   2. BOral antiviral therapy and urgent ophthalmology assessment
   3. CTopical aciclovir cream alone
   4. DOral antiviral therapy and routine GP review in 2 weeks
   Show answer and explanation▾

   Answer: B. Oral antiviral therapy and urgent ophthalmology assessment

   Vesicles on the nasal tip (Hutchinson sign) reflect nasociliary nerve involvement and predict ocular involvement, so prompt oral antiviral therapy and same-day ophthalmology review are needed to detect keratitis, uveitis or other complications. Topical antivirals are ineffective for zoster. Corticosteroids alone without antivirals are inappropriate and do not prevent post-herpetic neuralgia.

10. Question 10Cutaneous Neoplasms and Skin Cancerhard

    A 78-year-old man has a 2 cm painless, red-violet, rapidly growing nodule on the scalp that appeared over 6 weeks. Biopsy shows sheets of small round blue cells. Which immunohistochemical pattern supports Merkel cell carcinoma over metastatic small cell lung carcinoma?

    1. ACD45 positive and CK20 negative
    2. BCK20 negative and TTF-1 positive
    3. CS100 positive and HMB-45 positive
    4. DCK20 positive in a perinuclear dot pattern and TTF-1 negative
    Show answer and explanation▾

    Answer: D. CK20 positive in a perinuclear dot pattern and TTF-1 negative

    Merkel cell carcinoma typically shows paranuclear dot-like CK20 staining with neuroendocrine markers and is TTF-1 negative, whereas small cell lung carcinoma is usually CK20 negative and TTF-1 positive. S100 and HMB-45 positivity suggests melanoma, and CD45 suggests lymphoma. Staging includes sentinel lymph node biopsy in clinically node-negative disease because of the high rate of occult nodal spread.

11. Question 11Cutaneous Neoplasms and Skin Cancermedium

    A 64-year-old woman has a 9 mm infiltrative basal cell carcinoma on the nasal ala with ill-defined margins. Which treatment offers the highest cure rate while conserving tissue?

    1. ACurettage and cautery
    2. BTopical imiquimod 5% cream
    3. CCryotherapy
    4. DMohs micrographic surgery
    Show answer and explanation▾

    Answer: D. Mohs micrographic surgery

    An infiltrative BCC on the central face (H-zone) with ill-defined margins is high risk for recurrence, and Mohs micrographic surgery gives the highest cure rate with complete margin examination and maximal tissue preservation. Cryotherapy, imiquimod and curettage are appropriate for low-risk superficial lesions on the trunk or limbs. Infiltrative subtypes have subclinical extension that these methods cannot assess.

12. Question 12Hair, Nail, Adnexal and Mucous Membrane Disorderseasy

    A 29-year-old woman notices diffuse hair shedding beginning about 3 months after delivering her baby. The hair pull test is positive with club-shaped roots, and there is no scarring or patchy loss. What is the most likely diagnosis?

    1. ATelogen effluvium
    2. BFemale pattern hair loss
    3. CAlopecia areata
    4. DAnagen effluvium
    Show answer and explanation▾

    Answer: A. Telogen effluvium

    A physiological stress such as childbirth shifts many follicles into telogen, and diffuse shedding of club (telogen) hairs follows about 2 to 4 months later; postpartum shedding usually resolves within 6 to 12 months. Anagen effluvium occurs within days to weeks of chemotherapy and produces dystrophic, tapered hairs. Alopecia areata typically causes well-defined patches, and female pattern hair loss causes gradual central thinning rather than acute shedding.

13. Question 13Pigmentary Disorders and Photodermatosesmedium

    A 25-year-old man has stable non-segmental vitiligo affecting the eyelids and perioral skin, covering less than 3% of his body surface. What is the most appropriate first-line treatment for these facial patches?

    1. ATopical tacrolimus 0.1% ointment
    2. BMonobenzone depigmentation therapy
    3. CContinuous clobetasol propionate 0.05% for 6 months
    4. DOral methotrexate
    Show answer and explanation▾

    Answer: A. Topical tacrolimus 0.1% ointment

    Topical calcineurin inhibitors are preferred first-line for facial and eyelid vitiligo because they repigment effectively without the skin atrophy and periocular risks (such as glaucoma) of potent corticosteroids. Continuous use of a superpotent steroid on the face is inappropriate. Depigmentation therapy is reserved for extensive, refractory disease, and methotrexate is not first-line.

14. Question 14Pediatric Dermatology and Genodermatosesmedium

    A 7-week-old infant has a rapidly growing infantile haemangioma on the upper eyelid that is starting to cover the pupil. What is the most appropriate management?

    1. AWatchful waiting until natural involution
    2. BUrgent surgical excision under general anaesthesia
    3. CPulsed dye laser as the sole treatment
    4. DStart oral propranolol after appropriate pretreatment assessment
    Show answer and explanation▾

    Answer: D. Start oral propranolol after appropriate pretreatment assessment

    A periocular haemangioma obstructing the visual axis threatens amblyopia, and oral propranolol is the first-line systemic treatment, typically at 1 to 3 mg/kg/day, started early during the proliferative phase. Waiting for involution risks permanent visual impairment. Pulsed dye laser has limited effect on thick proliferating lesions, and surgery is rarely first-line.

15. Question 15Dermatologic Therapeutics and Pharmacologyhard

    A 67-year-old man with psoriasis taking weekly methotrexate 15 mg is prescribed trimethoprim-sulfamethoxazole for a urinary tract infection. Ten days later he has mouth ulcers and pancytopenia. Both drugs are stopped. What is the most appropriate specific treatment?

    1. AFolinic acid (leucovorin) rescue
    2. BOral folic acid 5 mg daily
    3. COral prednisolone
    4. DIntravenous immunoglobulin
    Show answer and explanation▾

    Answer: A. Folinic acid (leucovorin) rescue

    Trimethoprim-sulfamethoxazole inhibits folate metabolism and reduces methotrexate renal clearance, precipitating severe methotrexate toxicity with mucositis and myelosuppression. Folinic acid bypasses the dihydrofolate reductase block and is the specific antidote, given with supportive care. Folic acid requires dihydrofolate reductase to become active and is therefore ineffective in acute toxicity.

Last reviewed September 2026. Questions are original and written to the published exam blueprint; they are not taken from any real paper.