Development of diffuse cutaneous squamous cell carcinoma in situ after chemotherapy for ovarian carcinoma and remission with PD1-inhibitor.

This is a 74-year-old female, initially presenting with malignant pleural effusion, and evaluation revealed programmed cell death ligand 1 (PDL1)-positive stage IV high grade serous ovarian cancer. Following initiation of standard chemotherapy agents, carboplatin and paclitaxel, the patient developed a diffuse, itchy rash over her abdomen, back, and bilateral upper and lower extremities. Biopsy of the rash revealed a diffuse non-resectable cutaneous squamous cell skin carcinoma (cSCC) in situ. Consequently, a PD1-inhibitor was added to her neoadjuvant chemotherapy regimen, which resulted in complete response to both metastatic ovarian and diffuse cSCC in situ at time of surgery.