Pembrolizumab-induced pseudoepitheliomatous eruption consistent with hypertrophic lichen planus.

Pembrolizumab, an anti-programmed cell death-1 (PD-1) antibody preparation, has been shown to induce various dermatologic adverse events which may present with delayed onset or even after discontinuation of therapy. We report a 78-year-old female patient with a stage II lung adenocarcinoma treated with pembrolizumab, who developed lichenoid eruptions and multiple cutaneous plaque/nodular eruptions as pseudoepitheliomatous hyperplasia, during and up to 2 months after discontinuation of pembrolizumab therapy. Multiple skin biopsies revealed epidermal hyperplasia with hyperkeratosis, hypergranulosis, diffuse to patchy lichenoid lymphocyte infiltrate with scattered eosinophils and neutrophils, confluent to scant dyskeratosis of the lower epidermis, minimal to overt invagination, and cystic proliferation of squamous epithelium to papillomatosis with hypergranulosis and keratosis. Overall, multiple patterns were present with similarities to lichenoid drug eruption, lichen planus, early invasive squamous cell carcinoma, early keratoacanthoma, and verruca. However, the findings ultimately supported a diagnosis of hypertrophic lichen planus. All the lesions resolved with oral prednisone, hydroxychloroquine, and topical triamcinolone acetonide ointment 0.1%. In summary, our case shows that pembrolizumab can induce lichenoid eruption with pseudoepitheliomatous hyperplasia, and these lesions can clinically and pathologically mimic early invasive squamous cell carcinomas or keratoacanthomas.

Morbihan disease: a case report and differentiation from Melkersson-Rosenthal syndrome.

We present a 32-year old woman with a 9-year history of upper facial swelling. A workup by the ophthalmology department led to the diagnosis of Melkersson-Rosenthal syndrome. Re-evaluation in our dermatology clinic confirmed a diagnosis of Morbihan disease. Herein, we review case reports and case series of upper facial swelling in the dermatologic and ophthalmologic literature. Although the two entities share histopathological changes, they tend to have different clinical presentations. Melkersson-Rosenthal syndrome appears to be more likely diagnosed in the ophthalmologic literature when the clinical presentation and histopathology may be more consistent with Morbihan disease. In a patient with upper facial swelling, an absence of orolabial swelling, and lack of facial neuropathy, we argue for a diagnosis of Morbihan disease over Melkersson-Rosenthal syndrome, especially if the patient has a history of rosacea.