Lichen Planopilaris Pemphigoides: A Novel Bullous Dermatosis Due to Programmed Cell Death Protein-1 Inhibitor Therapy.

ABSTRACT: Lichen planus pemphigoides (LPPemph), apart from bullous pemphigoid, is a rare bullous dermatosis that can be induced by programmed cell death protein-1 (PD-1)/PD ligand 1 (PD-L1) inhibitors. The primary location of PD-1/PD-L1 inhibitor-induced LPPemph has previously only been reported at the nonfollicular dermal-epidermal junction. We present a case of nivolumab-induced LPPemph with an intense perifollicular lichenoid reaction, prominent multifocal perifollicular clefting, which in addition, was also accompanied by linear IgG and C3 immunofluorescence deposits along the dermal-epidermal junction as well as demonstrating a perifollicular pattern. Intriguingly, the serological study of BP180 and BP230 antibodies was negative, suggesting the presence of additional novel antibodies, which primarily favor hair follicles and may contribute to the pathogenesis. Therefore, we consider this entity a novel variant of PD-1/PD-L1 inhibitor-induced bullous dermatosis. To the best of our knowledge, this is the first report that highlights perifollicular bullae accompanied by immunofluorescence findings in a PD-1/PD-L1 inhibitor-induced lesion. We propose a new immunotherapy associated entity, lichen planopilaris pemphigoides, and emphasize the significance of perifollicular changes in the pathogenesis.

Melanoma Arising From a Pre-existing Neurofibroma in a Patient With No Prior Diagnosis of Systemic Neurofibromatosis 1 or 2: A Case Report.

ABSTRACT: The pathophysiology of melanoma involves malignant transformation of melanocytes. These can arise de novo or result from malignant transformation of a pre-existing nevus. This case report presents a patient with a new pigmented lesion, arising from a pre-existing neurofibroma, on her left scapula and no personal or family history of systemic neurofibromatosis. Biopsy confirmed the lesion to be malignant melanoma and, after excision, postoperative pathology showed a pre-existing neurofibroma. A review of the literature suggests there may be a link between the pathogenesis of neurofibroma and malignant melanoma, because NF1 mutations are observed in both neurofibromatosis and malignant melanoma. We hypothesize that the pre-existing neurofibroma created a proliferative environment that gave rise to the adjacent neoplasm. Further research is required to understand the shared pathway, because this may lead to novel forms of surveillance and treatment.