Nail Clubbing — SCE Dermatology MCQ
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Correct answer: D — VEGF and prostaglandin-E2 signalling drives distal fibrovascular tissue expansion
Explanation lettering: C = shown as B · D = shown as C · B = shown as D
B is correct. The prevailing model proposes that megakaryocytes and platelet clumps escape normal fragmentation in the pulmonary circulation, reach distal digital vessels and release mediators including platelet-derived growth factor and VEGF; increased PGE2 signalling also contributes. Vascular permeability and fibroblast proliferation expand the nail bed, increase fluctuation and abolish the normal Lovibond angle. Hypoxaemia alone is insufficient to explain the range of associated pulmonary, cardiac, hepatic and gastrointestinal conditions. Melanocytes cause pigmentation, dermatophytes cause onychomycosis, and matrix-destructive inflammation produces dystrophy rather than symmetrical bulbous enlargement.
Reference: GatewayC finger-clubbing clinical resource: https://www.gatewayc.org.uk/cancer-keys/finger-clubbing-an-easily-forgotten-red-flag/