A rare case and literature review of bullous pemphigoid appearing in the setting of lichen sclerosus: a dermatopathological conundrum and what to expect.

Co-occurrence of blisters in patients with lichen sclerosus (LS) can raise the question of whether they represent a bullous variant of LS or a concomitant autoimmune disorder. We report a rare case of bullous pemphigoid (BP) occurring on previous LS lesions. To the best of our knowledge, this is also the first BP180-negative case reported in literature. Here, we propose alternative mechanisms, independent of BP autoantibodies, that may lead to development of BP on skin affected by LS. In addition, we provide a literature review that explores the underlying pathophysiology and offers practical treatment insights, equipping clinicians with valuable guidance for similar complex cases.