Skin tumours flashcards
15 high-yield MRCP Part 1 cards from the Intellect Medicos Dermatology course. Try to answer each question before you open it — then study them properly with spaced repetition, which brings each card back just before you would forget it.
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What is the single most important prognostic factor in primary malignant melanoma?
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Breslow thickness (depth of invasion in mm).
Why? Deeper tumours are more likely to metastasise.
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What is the initial diagnostic step for a suspected melanoma in secondary care?
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Excision biopsy with a narrow (about 2 mm) clinical margin for histology; wide local excision follows, guided by Breslow thickness.
Why? Full-thickness histology gives the Breslow depth, which determines the final excision margin and staging.
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What is the mechanism of action of vemurafenib in metastatic melanoma?
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BRAF kinase inhibitor (used in BRAF V600-mutated melanoma).
Why? About half of melanomas carry an activating BRAF mutation driving the MAPK pathway.
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Ipilimumab, used in advanced melanoma, blocks which molecule?
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CTLA-4 (an immune checkpoint on T cells).
Why? Blocking this checkpoint releases the brake on T-cell activation against the tumour.
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The commonest subtype of malignant melanoma is ______ melanoma.
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superficial spreading
Why? It accounts for about 70% of cases. Nodular melanoma is the second commonest; it grows vertically early, so it is often thick at diagnosis and carries a poorer prognosis.
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How is a suspected basal cell carcinoma managed?
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Refer for surgical excision — usually a non-urgent (routine) referral, not the suspected cancer pathway.
Why? BCC is the commonest skin cancer; it grows slowly and very rarely metastasises.
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What is the first-line treatment for a single localised actinic keratosis?
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Cryotherapy.
Why? Actinic keratoses are premalignant sun-damage lesions that can progress to SCC.
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Which skin cancer shows the greatest increase in incidence in organ transplant recipients?
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Cutaneous squamous cell carcinoma.
Why? Long-term immunosuppression (e.g. azathioprine, ciclosporin) raises SCC risk many-fold, so these patients need sun protection and regular skin surveillance.
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How should a suspected cutaneous squamous cell carcinoma be referred from primary care?
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Consider a suspected cancer pathway (urgent) referral, aiming for cancer to be diagnosed or ruled out within 28 days.
Why? SCC can metastasise, unlike most BCCs (usually a non-urgent referral). Definitive treatment is surgical excision; Mohs surgery for cosmetically important sites.
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Pigment spreading from a longitudinal nail streak onto the proximal nail fold (Hutchinson's sign) suggests which diagnosis?
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Subungual (acral lentiginous) melanoma.
Why? Acral lentiginous melanoma affects palms, soles and nail beds, is not related to sun exposure, and is the commonest subtype in people with darker skin.
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What is the classic triad of Sézary syndrome?
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Erythroderma, generalised lymphadenopathy and circulating Sézary cells (atypical T cells with cerebriform nuclei).
Why? It is the leukaemic form of cutaneous T-cell lymphoma. Mycosis fungoides, the commonest CTCL, is a CD4+ T-cell lymphoma that starts as itchy eczema-like patches.
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Which two characteristic skin adverse effects occur with BRAF inhibitors such as vemurafenib?
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Photosensitivity and new cutaneous squamous cell carcinomas/keratoacanthomas.
Why? BRAF inhibition paradoxically activates the MAPK pathway in BRAF wild-type keratinocytes, driving new squamous tumours; regular skin checks are needed. Adding a MEK inhibitor reduces this.
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What is the mechanism of action of pembrolizumab and nivolumab in advanced melanoma?
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Monoclonal antibodies against PD-1 (programmed cell death protein 1), an immune checkpoint on T cells.
Why? Blocking PD-1 stops tumour PD-L1 from switching T cells off. Immune-related adverse effects include colitis, hepatitis, pneumonitis and endocrinopathies (thyroiditis, hypophysitis).
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Topical 5-fluorouracil, used for multiple actinic keratoses, inhibits ______; imiquimod is an immune response modifier that acts as a toll-like receptor 7 (TLR7) agonist.
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thymidylate synthase
Why? Both cause an expected local inflammatory reaction (redness, crusting, soreness) during treatment; warn patients in advance.
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Topical 5-fluorouracil, used for multiple actinic keratoses, inhibits thymidylate synthase; imiquimod is an immune response modifier that acts as a ______.
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toll-like receptor 7 (TLR7) agonist
Why? Both cause an expected local inflammatory reaction (redness, crusting, soreness) during treatment; warn patients in advance.