Navigating Through the Complexities of Bullous Presentation of Cutaneous Lichen Planus: A Comparative Study

Introduction: Bullous spectrum of cutaneous lichen planus has two distinct forms lichen planus pemphigoids (LPPs) and bullous lichen planus (BLP). There is paucity of literature on the clinical, histopathological, and immunological profile of this rare presentation. We aim to describe the clinical, histological, and immunological features of this distinct form further proposing an algorithmic approach for diagnosis.

Methodology: We conducted a retrospective observational study and reviewed cases of LPP and BLP which were diagnosed in the last 10 years (2011-21). Relevant information (clinical presentation, histology, immunofluorescence finding) was noted on pre-structured proforma and was analyzed.

Results: Out of 1960 biopsies of cutaneous lichen planus, only 21 cases had clinical suspected bullous presentation while immunofluorescence was received for only 16 cases. BLP was seen in the younger age group in comparison with LPPs (25.7 years vs 36.8 years). Bulla was seen in all cases. Dermo-epidermal junctional split was seen in all cases of BLP and LPP. On direct immunofluorescence (DIF) all the cases of LPP either had 1-2+ IgG and/or C3 while cases of BLP were not immunoreactive or had only colloid bodies.

Conclusion: This study describes in detail the clinicopathological profile of BLP and LPP and reiterates the importance of DIF during workup to arrive at a definitive diagnosis.