Ovarian cancer is one of the most malignant and aggressive tumors of the female reproductive system. Late diagnosis is one of the most significant problems: more than two-thirds of cases are detected only at stage III–IV. Ovarian cancer is characterized by a unique metastatic process. Implantation is the earliest and most common way of metastasis. It is often accompanied by fluid accumulation in the abdominal cavity, known as ascites. We report a case of low-grade serous ovarian carcinoma with a large heterogeneity of tumor cells in the ascitic fluid detected using multicolor flow cytometry. We demonstrated the advantages and benefits of this method in the diagnosis of ovarian cancer. Multicolor flow cytometry opens new horizons for liquid biopsy in oncology.

Ovarian cancer is considered to be the most malignant and aggressive tumor of the female reproductive system, which is largely associated with early development of malignant ascites and peritoneal carcinomatosis. Cancer cells representing the primary focus, as well as those contained in the ascitic fluid, are extremely heterogeneous in terms of morphological, immunohistochemical, and molecular genetic aspects. Cancer stem cells play a significant role in tumor self-renewal, differentiation, metastasis, and development of chemoresistance.This literature review is aimed at summarizing the available data on cancer stem cells in ovarian cancer and their role in tumor progression. A bioinformatic search was carried out in the PubMed, NCBI, Google Scholar, and eLibrary databases using the keywords “cancer stem cells”, “ovarian cancer”, “malignant ascites”, “chemoresistance”, etc.The data presented in the review make it possible to comprehensively characterize the role of stem cell properties of ovarian cancer cells. The review presents up-to-date information on the molecular and biological parameters of cancer stem cells in ovarian cancer, which are the cellular component of malignant ascites, as well as data from the authors’ studies. Along with this, the article describes modern ideas about the mechanisms of formation of cellular spheroids and their contribution to cancer progression.Cancer stem cells are an extremely promising target in the development of future therapeutic strategies based on the study of signaling pathways in ovarian cancer stem cells, the mechanisms of spheroid formation, and the contribution of immune cells to the acquisition of cancer stem cell properties.

Thymolipoma is a rare benign pathological tumor of the anterior mediastinum and accounts for about 2–9 % of thymus tumors. Tumor is usually represented as soft tissue consisting of adipose and thymic tissues. Because of the asymptomatic presentation, patients are often diagnosed with a large tumor. Gigantism of the tumor due to long-term and progressive compression of adjacent organs and anatomical structures of this region can lead to dysfunction, and in some cases, to a complete block of their activity, which is fraught with a fatal outcome. Preoperative diagnosis is always a difficult task due to the lower sensitivity of CT scans and biopsies. The main method of treatment is radical surgical excision. The article presents a clinical case of a 51-year-old patient with a giant tumor of the left hemithorax with a long-term asymptomatic presentation, who was diagnosed with thymolipoma after surgical excision and final histopathological examination.