Basic and Clinical Sciences Relevant to Dermatology
What the exam expects
You must be fluent in the layered anatomy of skin (epidermis, dermis, subcutis), the keratinocyte maturation sequence, and the cell types resident in each compartment (melanocytes, Langerhans cells, Merkel cells, mast cells, fibroblasts). Immunology is heavily weighted: antigen presentation, Th1/Th2/Th17 balance, cytokine families, complement pathways, and the difference between type I–IV hypersensitivity. Microbiology requires knowing organism classes (gram-positive cocci, dermatophytes, HPV serotypes, herpesviruses, atypical mycobacteria) and the pharmacology of drugs that target them, including mechanisms, metabolism (cytochrome P450), and major interactions.
Traps
Questions often test structure–function links (e.g., why the dermo-epidermal junction fails in pemphigoid versus pemphigus) or pharmacokinetic reasoning (which drug is a CYP3A4 inhibitor, which requires renal dose adjustment). Genetics questions favour inheritance patterns and the concept of mosaicism over rare syndrome names.
Rule of thumb
When a stem describes a defect, ask: which layer, which cell, which molecule? That triad usually narrows the answer to one option. For drug questions, anchor on mechanism first, then metabolism.
Worked example
A stem describes blistering with suprabasal acantholysis and asks which structure is targeted. Reasoning: split is intraepidermal, above the basal layer → desmosomal adhesion between keratinocytes → desmoglein. That avoids the trap of choosing hemidesmosome (which would give a subepidermal split).