Abstract:

Lichen planus pemphigoides (LPP), apart from bullous pemphigoid, is a distinct, however very rare bullous dermatosis. Recent literature describes cases induced by programmed cell death-1 (PD-1)/PD ligand 1 (PD-L1) inhibitors. We report a case of PD-L1 induced-LLP with unique histopathology. A 60-year-old male received nivolumab for metastatic hepatocellular carcinoma and developed recurrent, targetoid plaques and diffuse erythematous to dusky cyanotic patches on the right scalp. Histologically, in addition to the lichenoid interface infiltrate, multifocally prominent perifollicular clefting was seen, which was also associated with linear IgG and C3 immunofluorescence deposits. So far, the primary location of PD-1/PD-L1 inhibitor-induced LPP was only reported at non-follicular dermal-epidermal junction. Although lichen planopilaris can be induced by PD-1/PD-L1 inhibitors, no perifollicular bullae have been reported. Therefore, for the first time, we highlight the presence of perifollicular bullae by direct immunofluorescence. We consider this entity a novel variant of PD-1/PD-L1 inhibitor-induced bullous dermatitis and call it lichen planopilaris pemphigoides. Intriguingly, serology study of BP180 and BP230 antibodies in this patient was negative, suggesting additional unknown antibodies, which primarily favor hair follicles, and may contribute to the pathogenesis of lichen planopilaris pemphigoides. This may also explain perifollicular bullae as the primary lesion in this case, supporting it as a distinct entity rather than conventional LPP. Although, more cased base data is needed, we propose a new variant of PD-1/PD-L1 inhibitor-induced bullous dermatitis, lichen planopilaris pemphigoides, and emphasize the significance of the perifollicular immunodeposits in its pathogenesis.

Financial Disclosure:
No current or relevant financial relationships exist.

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Tara Howard