Hypertrophic lichenoid reactions secondary to anti-PD-1 therapy

Anti-programmed cell death (PD-1) treatment is a form of immunotherapy that has recently emerged to become an effective treatment for metastatic melanoma. Pembrolizumab and nivolumab are recombinant humanised anti-PD-1 monoclonal antibodies which prevent binding of ligands (PD-L1 and PD-L2) to tumour cells, reactivating cytotoxic T lymphocytes inducing anti-tumour immunity.
Anti-PD-1 therapy’s cutaneous adverse effect profile is relatively unknown although lichenoid reactions have been reported in small case series previously. We present two cases of hypertrophic lichenoid reactions whilst on anti-PD-1 therapy.
Case one is a 68 year old female with stage IV metastatic melanoma on nivolumab who developed multiple keratotic nodules on the extremities which clinically resembled squamous cell carcinomas. Biopsies however, showed the lesions to be hypertrophic lichenoid reactions. Due to progression of metastatic melanoma, the patient was palliated and the lichenoid reactions were untreated.
The second case is an 81 year old male with stage IIIC metastatic melanoma on pembrolizumab who developed a solitary violaceous hyperkeratotic plaque on his right lower limb. Punch biopsy confirmed the diagnosis of hypertrophic lichen planus. The lesion was treated with potent topical corticosteroids and also intralesional corticosteroids.

Dr. Mi Vu