A Novel Case of Eruptive Keratoacanthomas Associated with Apalutamide Treatment for Prostate Cancer

Abstract

Prostate cancer is the second most common cancer globally diagnosed in men¹, with more than 160,000 new cases each year in the United States.² Even with relatively high rates of survival, many deaths occur due to metastases. It most often metastasizes to bone, to other sites including lymph nodes, lungs, and liver as well.^1,3 A wide range of treatment options are currently available — active surveillance, surgery, radiation, chemotherapy, and hormonal therapeutics.² Although most patients experience remission with standard therapy, approximately 10-20% of prostate cancer cases are castration-resistant.⁴ Up to 16% of these patients show no evidence that the cancer has spread at the time of the castration-resistant diagnosis.⁴ Castration-resistance refers to continued tumor growth despite appropriate hormonal treatment. In February 2018, apalutamide, a nonsteroidal antiandrogen (NSAA), was approved by the Food and Drug Administration (FDA) as the first drug for non-metastatic castration-resistant prostate cancer.⁴

Recently, there have been cases reporting generalized eruptive keratoacanthomas (EKA) in association with use of the program cell death (PD-1) targeting drugs like nivolumab, pembrolizumab, and leflunomide when treating malignancy. ^5,6,7 However, based on our literature review, we were unable to find documented cases involving apalutamide. 

We present the case of an 86-year-old Caucasian male with castration-resistant prostate cancer following radical prostatectomy diagnosed with biopsy-confirmed EKA with squamous cell carcinoma (SCC) two and a half months after the initiation of apalutamide.