In previous clinical studies, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in patients with cancer has a high risk of aggravation and mortality than in healthy infected individuals. The inoculation with the COVID-19 vaccine reduces the risk of SARS-CoV-2 infection and COVID- 19 severity. However, vaccination-induced production of anti-SARS-CoV-2 antibodies is said to be lower in patients with cancer than in healthy individuals. Additionally, the rationale for why patients with cancer become more severe with COVID-19 is not well understood. Therefore, we examined the infection status of SARS-CoV-2 in primary tumor and micrometastasis tissues of patients with cancer and COVID-19. In this study, angiotensin-converting enzyme 2 (ACE2) expression was observed, and SARS-CoV-2 particles were detected in ovarian tissue cells in contact with the micrometastatic niche of high-grade serous ovarian cancer. We believe that more severe COVID-19 cases in patients with cancer may be attributed to these pathological features.

Two-stage surgery is unintentionally necessary when total tumor removal cannot be accomplished in the first surgery, although, it has not yet been established how to leave the tumor for the next surgery. There is a risk of postoperative hemorrhage in the residual tumor, especially in hypervascular tumors. We report a case of hypervascular choroid plexus papilloma in which preservation of intratumoral venous drainage was considered important to avoid hemorrhagic complications during a two-stage surgery. In hypervascular tumor resection, to prevent postoperative hemorrhage associated with a residual tumor, it may be important to preserve venous drainage of the tumor.