A patient has lichen planus pigmentosus. Unlike classic LP, the DIF finding most commonly seen in LP pigmentosus is:
- A Linear IgG at the DEJ
- B Fibrinogen and fibrin deposits at the DEJ with IgM civatte bodies ✓
- C Granular IgA in dermal papillae
- D No immunoreactant deposits — DIF is negative
Correct answer: B. Fibrinogen and fibrin deposits at the DEJ with IgM civatte bodies
Explanation
Lichen planus (classic and variants) characteristically shows fibrinogen deposition at the DEJ and IgM (less often IgG, IgA) staining of colloid/Civatte bodies (apoptotic keratinocytes) on DIF. These colloid bodies represent keratinocytes undergoing liquefactive degeneration at the DEJ, and they bind IgM non-specifically. LP pigmentosus shows the same DIF pattern. Granular IgA at dermal papillae is DH; linear IgG at DEJ is bullous pemphigoid.
Reference: Neena Khanna Illustrated Synopsis of Dermatology & STD, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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