Skin Lesion Morphology
Primary: Macule, papule, patch, plaque, nodule, vesicle, bulla, pustule, wheal.
Secondary: Scale, crust, fissure, ulcer, scar, atrophy, excoriation.
Common Rashes
- Psoriasis: Well-demarcated erythematous plaques with silvery scale. Auspitz sign.
- Pityriasis rosea: Herald patch + Christmas tree distribution. Collarette scaling.
- Lichen planus: Purple, polygonal, pruritic papules. Wickham striae.
Blistering Disorders
- Bullous pemphigoid: Tense bullae, elderly, IgG at BMZ
- Pemphigus vulgaris: Flaccid bullae, positive Nikolsky, IgG against desmoglein 3
Pigmented Lesions
Melanoma (ABCDE rule), Dysplastic nevus, Becker nevus, Cafe-au-lait spots, Vitiligo.
References & further reading
Every clinical claim in this article is anchored to a primary source. Click through to verify, and use the same habit in your revision.
Revision history
- 19 September 2026 — Initial publication
Frequently asked questions
How many dermatology questions in UPSC CMS?
Typically 2-3 dermatology questions in Paper I. Most are image-based — showing a rash or lesion and asking for diagnosis or treatment.
What is the difference between macule, papule, plaque, and nodule?
Macule = flat, <1cm (freckle). Papule = raised, <1cm (wart). Plaque = flat-topped, >1cm (psoriasis). Nodule = raised, extends into dermis (dermatofibroma).
Which dermatology textbook for exams?
Habif Clinical Dermatology Color Atlas is excellent for image-based learning. For Indian exams: Neeraja textbooks or self-study notes with image banks.
Related reading
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