PEComa (Perivascular epithelioid cell tumors) are a rare type of tumor composed of cells exhibiting characteristics of smooth muscle cells and melanocytes. They most commonly occur in the female genital system. This study is a narrative review based on the differential diagnosis of tumors in the female genital system, focusing on PEComa. The aim of the research is to analyze the immunohistochemical markers characteristic of PEComa in the female genital system and compare them with markers of tumors that may appear in the differential diagnosis. Specifically, the study examines epithelioid smooth muscle tumor (STUMP), malignant melanoma, alveolar soft part sarcoma (ASPS), poorly differentiated endometrial carcinoma (EC) and trophoblastic tumors of the placenta (PSTT). Comparison of immunohistochemical markers of PEComa with markers of other tumors revealed that: PEComas show overlap in positive staining with STUMP, but are distinguished by markers such as HMB45, PNL2, MiTF, and MelanA/MART1; PEComas share some melanocytic markers with malignant melanoma, but differ in the expression of myogenic markers and hormone receptors; compared to ASPS, PEComas share some positive staining but differ in marker expression and negative staining; they differ from EC by the expression of specific markers such as MiTF and PAX8; PSTT show specificity for markers of trophoblastic differentiation and implantation, while PEComas emphasize melanocytic and myogenic differentiation. The general conclusion is that an accurate diagnosis of PEComa in the female genital system can only be achieved through a multidisciplinary approach. Immunohistochemical evaluation serves as a helpful tool, but standard morphological staining remains the gold standard. Also, the advanced diagnostic techniques, particularly next-generation sequencing, hold promise for enhancing the understanding and management of mPEComas. By uncovering the genomic landscape and facilitating targeted therapies, these methodologies may lead to more effective treatment and improved outcomes. Keywords: female genital system, epithelioid smooth muscle tumor, malignant melanoma, endometrial carcinoma, trophoblastic tumor.

Introduction: The lymphatic vasculature is an important route for the metastatic spread of human cancer. However, the extent to which this depends on lymphangiogenesis or on invasion of existing lymph vessels remains controversial. The goal of this study was to investigate the existence of lymphangiogenesis in invasive breast carcinoma: by measuring the lymphatic vessels density (LVD) and lymphatic endothelial cell proliferation (LECP) and their correlation with various prognostic parameters in breast cancer, including lymphovascular invasion (LVI).Methods: Lymphatic vessels density was investigated in 75 specimens of invasive breast carcinoma by immunostaining for D2-40 using the Chalkley counting method. Endothelial proliferation in lymphatic vessels was analyzed by dual-color immunohistochemistry with D2-40 and Ki-67.Results: Decrease of intra and peritumoral LVD in invasive breast carcinoma compared to fibrocystic breast disease was detected (p=0.002). Lymphatic endothelial cell proliferation was significantly higher in invasive breast cancer (p=0.008) than in the fibrocystic breast disease. LECP showed a correlation with histological grade of the tumor (p=0.05). Involvement of axillary lymph nodes with metastatic tissue was in strong correlation only with existence of lymphatic vascular invasion (p=0.0001).Conclusion: These results suggest that development of breast cancer promotes proliferation of lymphatic endothelial cells whose level correlates with histological grade of tumor, but in a scope that is insufficient to follow growth of tumor tissue that invades them and destruct them. This might explain the decrease of lymphatic vessels density.