Direct immunofluorescence of lesional skin from a patient with violaceous polygonal papules on the flexor wrists is most likely to show which combination of findings?
- A Intercellular IgG throughout the full thickness of the epidermis
- B Continuous granular IgG and C3 along the basement membrane zone of sun-exposed skin
- C Globular deposits of IgM in the papillary dermis corresponding to colloid bodies, together with shaggy fibrin deposition along the basement membrane zone ✓
- D Granular IgA deposited selectively in the tips of dermal papillae
Correct answer: C. Globular deposits of IgM in the papillary dermis corresponding to colloid bodies, together with shaggy fibrin deposition along the basement membrane zone
Explanation
In lichen planus, apoptotic basal keratinocytes become colloid (Civatte) bodies that trap immunoglobulin, chiefly IgM, giving clustered globular deposits in the upper dermis; shaggy fibrinogen along the basement membrane zone reflects chronic interface damage. Option B describes the lupus band of cutaneous lupus erythematosus, option A is pemphigus vulgaris, and option D is dermatitis herpetiformis.
Reference: Rook's Textbook of Dermatology, 9th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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