Free Dermatology mock test

Dermatology sample questions with answers

10 more original exam-style Dermatology questions, worked in full. They are not real or recalled exam questions, and none of them is in the mock above or on the bank page, so sit the mock first if you have not.

1. Question 1 · Cutaneous Infections, Infestations, Bites and Sexually Transmitted Infections

   A registrar is calculating the LRINEC (Laboratory Risk Indicator for Necrotising Fasciitis) score for a patient with a severe soft-tissue infection. Which of the following laboratory parameters is a component of that score?

   1. ASerum albumin
   2. BSerum lactate
   3. CSerum sodium
   4. DPlatelet count
   Show answer and explanation

   Correct answer: C. Serum sodium

   The LRINEC score is built from six variables: C-reactive protein, total white cell count, haemoglobin, serum sodium, serum creatinine and serum glucose, with hyponatraemia (<135 mmol/L) scoring points. Albumin, lactate and platelet count, although often deranged in sepsis, are not part of the score. LRINEC supports but never replaces clinical judgement, and a low score does not exclude necrotising fasciitis.

   Reference: Wong CH et al. The LRINEC score: a tool for distinguishing necrotizing fasciitis from other soft tissue infections. Crit Care Med, 2004

2. Question 2 · Cutaneous Neoplasms and Skin Cancer

   A 54-year-old man is referred with two yellowish papules on the trunk that on histology are a sebaceous adenoma and a sebaceoma; a third lesion was reported as a keratoacanthoma with sebaceous differentiation. He had a right-sided colonic adenocarcinoma at age 46 and his sister had endometrial carcinoma at 44. Which additional investigation is most likely to confirm the underlying syndrome?

   1. ASerum alpha-fetoprotein and carcinoembryonic antigen
   2. BImmunohistochemistry for mismatch repair proteins (MLH1, MSH2, MSH6, PMS2) and microsatellite instability testing on the tumour tissue, with germline testing
   3. CGermline PTEN sequencing
   4. DSkeletal survey for osteomas
   Show answer and explanation

   Correct answer: B. Immunohistochemistry for mismatch repair proteins (MLH1, MSH2, MSH6, PMS2) and microsatellite instability testing on the tumour tissue, with germline testing

   Sebaceous neoplasms (adenoma, sebaceoma, sebaceous carcinoma) or keratoacanthomas with sebaceous differentiation, together with visceral malignancies of the Lynch spectrum such as right-sided colorectal and endometrial cancer, indicate Muir-Torre syndrome, the cutaneous variant of Lynch syndrome caused by germline mismatch repair mutations, most often MSH2. Loss of mismatch repair protein expression with microsatellite instability on the sebaceous tumour is the recognised screening step before germline confirmation. Tumour markers are non-diagnostic, PTEN mutation causes Cowden syndrome with trichilemmomas, and osteomas point to Gardner syndrome.

   Reference: John AM, Schwartz RA, Muir-Torre syndrome review (BJD, 2016); NCCN Genetic/Familial High-Risk Assessment: Colorectal (2024)

3. Question 3 · Connective Tissue Disease, Dermal, Subcutaneous, Metabolic and Systemic Skin Disease

   A 44-year-old woman has hyperkeratotic, fissured, scaly lateral surfaces of the fingers, Raynaud phenomenon, inflammatory arthritis, fever and progressive dyspnoea with basal reticulation on high-resolution CT. Which single test best confirms the unifying diagnosis?

   1. AAnti-Jo-1 (and extended antisynthetase antibody panel)
   2. BAnti-cyclic citrullinated peptide antibody
   3. CPatch testing to a standard series
   4. DSerum ACE level
   Show answer and explanation

   Correct answer: A. Anti-Jo-1 (and extended antisynthetase antibody panel)

   Mechanic's hands with interstitial lung disease, arthritis, fever and Raynaud phenomenon is the antisynthetase syndrome, confirmed by antisynthetase antibodies of which anti-Jo-1 is the commonest (others include PL-7, PL-12, EJ, OJ). Anti-CCP indicates rheumatoid arthritis and would not explain mechanic's hands, patch testing addresses contact dermatitis which does not cause ILD, and serum ACE is a non-specific sarcoidosis marker with poor diagnostic performance.

   Reference: Bolognia, Jorizzo & Schaffer, Dermatology, 5th ed. (2024); Connors GR et al., antisynthetase syndrome review, Chest (2010) and subsequent ATS/ERS ILD statements

4. Question 4 · Procedural, Surgical, Laser and Cosmetic Dermatology

   Five days after a full-thickness skin graft to the nasal tip, the graft surface is black and adherent with no surrounding erythema, warmth, fluctuance or systemic upset. What is the most appropriate management?

   1. AImmediate sharp debridement of the whole graft and re-grafting
   2. BLeave the eschar undisturbed, continue moist wound care and dressings, and review regularly until demarcation occurs
   3. CStart intravenous antibiotics and admit for observation
   4. DApply silver nitrate to the graft to hasten separation
   Show answer and explanation

   Correct answer: B. Leave the eschar undisturbed, continue moist wound care and dressings, and review regularly until demarcation occurs

   A black adherent graft at day five is usually a dry eschar of the superficial graft layers, beneath which the deeper dermal component may still take, and it also acts as a biological dressing; the correct approach is conservative moist wound care with serial review, since many such grafts heal with a good result and any true necrosis will demarcate over 2-3 weeks. Early debridement and re-grafting discards viable tissue, intravenous antibiotics are unwarranted without signs of infection, and silver nitrate is caustic and impairs re-epithelialisation.

   Reference: Robinson JK et al., Surgery of the Skin: Procedural Dermatology, 4th ed., Elsevier, 2022 (grafts and postoperative complications)

5. Question 5 · Dermatologic Therapeutics and Pharmacology

   A 66-year-old man with a 30 pack-year smoking history and treated hypertension has severe alopecia areata and asks about an oral JAK inhibitor. Which consideration most affects the decision?

   1. AJAK inhibitors are contraindicated in anyone over 60 regardless of other factors
   2. BHis age over 65, smoking history and cardiovascular risk factors place him in the group for whom regulators advise JAK inhibitors only if no suitable alternative exists
   3. CJAK inhibitors are entirely free of thromboembolic risk in dermatological indications
   4. DOnly baseline lipids need checking; no other risk stratification is required
   Show answer and explanation

   Correct answer: B. His age over 65, smoking history and cardiovascular risk factors place him in the group for whom regulators advise JAK inhibitors only if no suitable alternative exists

   Following the ORAL Surveillance safety data, regulators advise using JAK inhibitors in patients aged 65 or older, current or past long-term smokers, and those with cardiovascular or malignancy risk factors only when no suitable alternative treatment exists, with the lowest effective dose. Age alone is not an absolute contraindication, thromboembolic and major adverse cardiovascular signals are class warnings, and monitoring extends beyond lipids to blood counts, liver function and infection and malignancy surveillance.

   Reference: EMA PRAC review of JAK inhibitors (2023); FDA boxed warning for JAK inhibitors (2021); ORAL Surveillance, N Engl J Med (2022)

6. Question 6 · Vesiculobullous and Autoimmune Blistering Diseases

   A 72-year-old man with bullous pemphigoid has achieved clinical remission and his systemic corticosteroid is being tapered. Which investigation is most useful for monitoring disease activity and anticipating relapse during the taper?

   1. ASerial peripheral blood eosinophil counts
   2. BSerial total serum IgE levels
   3. CSerial serum anti-BP180 NC16A ELISA index values
   4. DRepeat lesional histology every three months
   Show answer and explanation

   Correct answer: C. Serial serum anti-BP180 NC16A ELISA index values

   Anti-BP180 NC16A ELISA titres correlate with disease activity in bullous pemphigoid, and persistently high or rising values at the end of treatment predict relapse, making serial ELISA the most useful monitoring tool alongside clinical scoring. Eosinophil count and total IgE are non-specific and less well correlated, and repeat histology is invasive and does not track activity.

   Reference: Borradori L et al. Updated S2k guidelines for the management of bullous pemphigoid initiated by the European Academy of Dermatology and Venereology. J Eur Acad Dermatol Venereol 2022

7. Question 7 · Papulosquamous and Eczematous Dermatoses

   A 34-year-old woman with severe plaque psoriasis has coexisting ileocolonic Crohn disease that is currently in remission. Methotrexate has failed and biologic therapy is planned. Which agent is least appropriate because of a recognised risk of exacerbating her bowel disease?

   1. AInfliximab
   2. BRisankizumab
   3. CSecukinumab
   4. DUstekinumab
   Show answer and explanation

   Correct answer: C. Secukinumab

   IL-17A blockade with secukinumab (and ixekizumab or brodalumab) has been associated with new-onset or flaring inflammatory bowel disease and failed in Crohn trials, so it is avoided when IBD coexists. Infliximab, ustekinumab and risankizumab are all effective in both psoriasis and Crohn disease, making them rational choices for this patient.

   Reference: Hueber et al., Gut, 2012 (secukinumab in Crohn disease); AAD-NPF guidelines for the management of psoriasis with biologics, 2019

8. Question 8 · Urticaria, Erythemas, Drug Eruptions, Purpura and Cutaneous Vasculitis

   A 58-year-old man has recurrent lower-limb purpura worse in cold weather, arthralgia, peripheral neuropathy, low C4 with near-normal C3, and proteinuria. Which underlying condition should be excluded first?

   1. AHereditary angioedema
   2. BCoeliac disease
   3. CLatent tuberculosis
   4. DChronic hepatitis C virus infection
   Show answer and explanation

   Correct answer: D. Chronic hepatitis C virus infection

   The triad of purpura, arthralgia and weakness with neuropathy, membranoproliferative glomerulonephritis and a markedly low C4 with relatively preserved C3 is typical of mixed (type II) cryoglobulinaemic vasculitis, which is most often driven by chronic hepatitis C infection; HCV serology and RNA testing should be performed. Coeliac disease and latent tuberculosis do not produce this complement pattern, and hereditary angioedema causes non-purpuric bradykinin-mediated swelling with low C4 but no vasculitis.

   Reference: Chapel Hill Consensus Conference nomenclature (2012); Ramos-Casals et al., The cryoglobulinaemias, Lancet

9. Question 9 · Basic Science, Skin Biology, Cutaneous Immunology and Dermatopathology

   A 4-year-old with severe atopic dermatitis has repeated episodes of impetiginised eczema with heavy Staphylococcus aureus growth, yet has no history of deep abscesses, invasive infection or delayed umbilical cord separation, and neutrophil counts and function are normal. Which mechanism best explains his cutaneous susceptibility to S. aureus?

   1. AConstitutive overproduction of cathelicidin LL-37 by keratinocytes
   2. BInherited deficiency of the terminal complement components C5 to C9
   3. CDefective neutrophil NADPH oxidase with failure of the respiratory burst
   4. DTh2 cytokines IL-4 and IL-13 suppress keratinocyte production of antimicrobial peptides such as LL-37 and human beta-defensins
   Show answer and explanation

   Correct answer: D. Th2 cytokines IL-4 and IL-13 suppress keratinocyte production of antimicrobial peptides such as LL-37 and human beta-defensins

   In atopic dermatitis the Th2 milieu, together with barrier failure, downregulates keratinocyte antimicrobial peptides (cathelicidin LL-37, human beta-defensin 2 and 3), permitting dense S. aureus colonisation and superinfection while systemic immunity remains intact. Excess LL-37 processing is characteristic of rosacea, not atopic dermatitis. Terminal complement deficiency predisposes to recurrent Neisseria infection, and NADPH oxidase deficiency causes chronic granulomatous disease with deep abscesses and granulomas, neither of which fits this clinical picture.

   Reference: Ong PY et al. Endogenous antimicrobial peptides and skin infections in atopic dermatitis. N Engl J Med, 2002; AAD guidelines of care for atopic dermatitis, 2023

10. Question 10 · Pediatric Dermatology and Genodermatoses

    A 15-month-old boy has several firm yellow-orange domed papulonodules on the scalp and trunk that appeared over the past 6 months, and six café-au-lait macules greater than 5 mm with axillary freckling. Which additional risk should prompt specific monitoring in this child?

    1. AJuvenile myelomonocytic leukaemia
    2. BWilms tumour
    3. CHepatoblastoma
    4. DMedulloblastoma
    Show answer and explanation

    Correct answer: A. Juvenile myelomonocytic leukaemia

    The combination of multiple juvenile xanthogranulomas with neurofibromatosis type 1 is associated with an increased risk of juvenile myelomonocytic leukaemia, so periodic clinical review with attention to pallor, bleeding, organomegaly and a full blood count is warranted. Cutaneous juvenile xanthogranulomas themselves are benign and usually involute spontaneously; the important direct complication of JXG is ocular involvement with spontaneous hyphaema, which is why ophthalmology review is advised for young children with multiple lesions. Wilms tumour, hepatoblastoma and medulloblastoma are linked with other syndromes such as WAGR/Beckwith-Wiedemann, familial adenomatous polyposis and Gorlin syndrome respectively.

    Reference: Paller & Mancini, Hurwitz Clinical Pediatric Dermatology, 6th ed. (2022), chapter on Histiocytoses