Morphology: describe skin lesions examined through visual and tactile inspection by using key descriptors (e.g., size, shape, color, texture, configuration, distribution, secondary features, palpability). Here’s a cheat sheet to supplement the resident teaching you’ll have on this:

Primary lesions (the “family” of the disease process) are in pink. Secondary features/lesions (changes superimposed upon primary lesion either due to outside manipulation or evolution of primary lesion) are in blue.

  • Raised
    • Palpable: Papule (<1cm; ex: wart) → Plaque (>1cm; ex: psoriasis)
    • Deeper in skin: Nodule (>1cm; ex: dermatofibroma) → Tumor (solid, firm, >2cm; ex: metastatic carcinoma)
    • Wheal: edematous papule/plaque; often erythematous border & pale center; ex: urticaria
    • Scale: “dead skin” flakes of compacted, desquamated stratum corneum layers 
    • Crust: “scab” of dried serum, exudate or blood
    • Scar/Keloid: dermis damage → permanent fibrotic changes; keloids extend beyond original defect 
    • Lichenification: epidermal thickening with exaggeration of normal skin lines; usually due to chronic rubbing or scratching
  • Flat
    • Color change only: Macule (<1cm; ex: freckle) → Patch (>1cm; ex: vitiligo)
  • Depressed
    • Erosion (breakdown; ex: ruptured varicella vesicles) → Ulcer (complete loss; ex: venous stasis ulcer)
    • Atrophy: skin thinning
    • Excoriation: trauma area due to rubbing or scratching; ex: neurotic excoriations from habitual picking
    • Fissure: site of skin cleavage extending into dermis; ex: interdigital tinea pedis  
    • Burrow: thread-like linear or serpiginous tunnel, typically made by parasite; ex: scabies 
  • Fluid-filled
    • Serous fluid-filled papules (small blisters): Vesicle (<1cm; ex: herpes zoster) → Bulla (>1cm; ex: pemphigus vulgaris)
    • Pus-filled space: Pustule (not all are infected; ex: bacterial folliculitis) → Furuncle (acute, follicle-centered nodule, >1cm; ex: S. aureus infection) → Carbuncle (2 or more confluent furuncles with separate heads; ex: S. aureus infection) → Abscess (red, warm, tender; ex: MRSA infection)
    • Cyst: epithelial-lined sac-like nodule containing fluid/debris; ex: epidermal inclusion cyst
  • Vascular 
    • Erythema: blanchable pink/red hue indicating vascular dilation; not a color
    • Telangiectasia: dilated small, superficial cutaneous blood vessel; ex: erythrotelangiectatic rosacea
    • Non-blanchable, bleeding into skin: Petechiae (pinpoint; ex: Rocky Mountain spotted fever) → Purpura (1cm; ex: Henoch-Schönlein purpura) → Ecchymosis (>1cm; ex: bruise from blunt trauma) 

Distribution: pattern in which multiple lesions are arranged; involves multiple body surfaces

Acral: distal aspects of head & extremities Dermatomal: sensory nerve root distribution; ≠ cross midlineIntertriginous: skin creases & foldsLymphangitic: along lymph channels of leg/arm Photodistributed: on sun-exposed skinScattered: randomly distributed on body Symmetric: symmetrically on extremitiesWidespread: spans body 

Lesion Shape or Configuration

Annular: ring-shapedArcuate: arc-shaped Grouped: clustered   Linear: straight linePolycyclic: coalescing circles/ringsReticular: netlikeScattered: irregularly distributed Serpiginous: wavy; snakelike Targetoid: target-like, “bull’s eye” Whorled: stirred appearance

For a review of the diseases you are expected to have a general understanding of by the end of your rotation: Click here.