Abstract Number: 323

Case Report: Eruptive keratoacanthomas associated with Pembrolizumab

O. Tonge1, P. Lowe1,2, P. Guitera1,3,4, H. Collgros1,3

Meeting: 2021 Dermcoll

Session Information

Date: -

Session Title: Poster Presentations

Session Time: -

Pembrolizumab is an immune checkpoint inhibitor anti- PD1 (Anti-programmed Cell Death-1) drug approved for metastatic melanoma, non-small cell lung cancer and head and neck squamous cell carcinoma (SCC). Most adverse effects of anti-PD1 drugs are immune-related. Approxi- mately 40% of patients treated with anti-PD1 develop cuta- neous toxicity. Eruptive keratoacanthomas (KA) have been reported as a rare side effect of anti-PD1(1). We present a case of a 73-year-old male who presented with rapidly pro- gressing cutaneous lesions after 12 weeks of pem- brolizumab for stage IV lung cancer. He had pink plaques on his lower limbs and forearms, having had only mild improvement with topical corticosteroids. The largest kera- totic papule on the lower leg was excised, confirming well- differentiated SCC. Four months later, lesions were increas- ing in both size and number. Three punch biopsies con- firmed well-differentiated SCCs. With a clinical diagnosis of eruptive KAs secondary to pembrolizumab, he commenced acitretin 30 mg daily. One month later he was hospitalised for lower limb cellulitis; pembrolizumab was ceased tem- porarily and acitretin continued. Subsequently he developed extensive bullous pemphigoid requiring oral prednisone. Keratinocytic tumours but eruptive KAs are rare with anti- PD1 and few cases have been reported, most of them regressing spontaneously or after treatment with topical and/or intralesional corticosteroids, cryotherapy, curettage and imiquimod Although not statistically significant, it has been reported that patients undergoing anti-PD1 ther- apy develop more SCCs than controls, hypothesising that immunosuppression may play a more relevant role. Paradoxically, pembrolizumab is also used to treat metastatic or
locally advanced SCCs with promising results


1. Antonov NK, Nair KG, Halasz CL. Transient eruptive keratoa- canthomas associated with nivolumab. JAAD Case Rep. 2019;5 (4):342–5.
2. Zhao CY, Hwang SJE, Anforth R, Carlos G, Chou S, Carlino M, Ferna’ndez-Pen~as P. Incidence of Basal Cell Carcinoma and Squamous Cell Carcinoma in Patients on Antiprogrammed Cell Death-1 Therapy for Metastatic Melanoma. J Immunother. 2018