[Clinical Picture] Pseudoprogression of a cutaneous lung cancer metastasis

A 38-year-old man presented to the Rocket Force Characteristic Medical Center (Beijing, China) in September, 2020, with limping, dizziness, and bone pain. PET/CT scan suggested lung cancer with bone and brain metastases, and a small cutaneous metastasis located on the lateral chest wall. Iliac bone lesion biopsy revealed poorly differentiated adenosquamous carcinoma originating from the lungs with negative PD-L1 expression (using the 22C3 assay). Next-generation sequencing of fresh biopsy tissue showed BRIP1 germline mutation and a high tumour mutational burden; mutations were detected in genes including TP53, SMARCA4, and ATM, but not in EGFR, ALK, ROS1, or KRAS.