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SU18.1-3 | Skin and Subcutaneous Tissue — Practice Quiz
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A young man has a tense, exquisitely tender, fluctuant swelling on his buttock with overlying redness. He has already completed a course of oral antibiotics with no improvement. What is the most appropriate management?
Correct. Fluctuance means pus, and pus must be let out — ubi pus, ibi evacua. Antibiotics will not cure a true abscess; incision and drainage is required.
The governing surgical principle is 'where there is pus, let it out'. Cellulitis without a collection is treated medically; a fluctuant abscess is drained.
A fluctuant collection is an abscess. Antibiotics cannot penetrate and cure a walled-off collection of pus — the treatment is incision and drainage.
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A diabetic patient has rapidly spreading redness of the leg with pain that is far out of proportion to the visible skin changes, skin crepitus, and systemic toxicity. What is the most important immediate action?
Correct. Pain out of proportion, crepitus and toxicity signal necrotizing fasciitis — a surgical emergency needing urgent radical debridement plus broad-spectrum IV antibiotics and resuscitation.
Pain out of proportion to physical findings is the red flag for necrotizing fasciitis. It is a surgical emergency; antibiotics alone are never sufficient.
This is necrotizing fasciitis. Pain out of proportion to the skin signs, crepitus and systemic toxicity demand urgent surgical debridement and IV antibiotics — delay is fatal.
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A patient presents with diffuse, spreading redness, warmth and tenderness of the lower leg without any fluctuant point, and is mildly febrile. What is the correct initial management?
Correct. Cellulitis is a diffuse spreading infection without a drainable collection — treat medically with antibiotics, elevation and analgesia, and mark the edge to track progress.
Cellulitis (diffuse, non-suppurative) is treated medically; an abscess (fluctuant, suppurative) is drained. Distinguishing them at the bedside is the core skill.
Cellulitis without fluctuance has no collection to drain; it is treated medically. Marking the margin lets you see whether the infection is spreading or settling on antibiotics.
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An elderly farmer has a slowly enlarging ulcer on the side of the nose with a raised, rolled, pearly margin and central crusting. It has never metastasised in two years. What is the most likely diagnosis?
Correct. A pearly, rolled-edge ulcer with central crusting on sun-exposed skin that erodes locally but does not metastasise is a basal cell carcinoma — the classic rodent ulcer.
BCC rarely metastasises and is dangerous by local erosion; SCC can spread to lymph nodes. This distinction earns the marks and protects the patient.
The pearly, raised, rolled margin on sun-exposed skin with local erosion and no metastasis is the hallmark of basal cell carcinoma (rodent ulcer). SCC, by contrast, can spread to lymph nodes.
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A long-standing venous ulcer or old burn scar develops a raised, everted, bleeding edge that fails to heal. Which malignant transformation must you suspect?
Correct. Squamous cell carcinoma arising in a chronic wound, scar or sinus is a Marjolin's ulcer — an everted, non-healing edge that must be biopsied.
SCC features an everted edge and can metastasise to regional nodes. A non-healing ulcer or scar edge that changes is malignant until proven otherwise — biopsy it.
A Marjolin's ulcer is a squamous cell carcinoma arising in chronic scar tissue or a long-standing ulcer. Its everted, non-healing edge demands biopsy.
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When assessing a pigmented skin lesion for possible melanoma, the ABCDE rule prompts you to look for which set of features?
Correct. For pigmented lesions the ABCDE rule is Asymmetry, Border irregularity, Colour variation, Diameter >6 mm, and Evolution (change over time). Breslow thickness then guides prognosis.
Melanoma ABCDE flags suspicious pigmented lesions; Breslow thickness (depth of invasion) is the key prognostic factor and guides excision margins.
For melanoma, ABCDE means Asymmetry, Border irregularity, Colour variation, Diameter >6 mm and Evolution. (The trauma ABCDE — Airway, Breathing… — is a different mnemonic.)
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While examining a swelling, you find that pressing on one side makes a bulge appear on the opposite side, and the swelling cannot be emptied or reduced. What does this 'fluctuation' sign indicate?
Correct. Fluctuation — a bulge transmitted to the opposite side on pressure — indicates that the swelling contains fluid, such as pus in an abscess, blood, or cyst fluid.
Examine every swelling in a fixed order (inspection, palpation, percussion, auscultation, nodes). Fluctuation = fluid; always examine the regional lymph nodes as part of every swelling examination.
Fluctuation indicates a fluid-containing swelling (pus, blood, cyst fluid). A solid swelling does not fluctuate. Each special sign points to a particular tissue or pathology.
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Which step is an essential, non-optional part of the clinical examination of EVERY surgical swelling, regardless of its apparent benignity?
Correct. The regional lymph nodes are part of the examination of every swelling, not an optional extra — matted or hard nodes may be the only clue to malignancy.
Two safe habits: always examine the regional lymph nodes, and let investigations follow (not replace) the clinical examination.
Always examine the regional lymph nodes for every swelling. Investigations follow clinical examination, not replace it — biopsy and imaging are selective, but node examination is universal.
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