The importance of histopathological examination in the diagnosis of myxoid leiomyosarcoma.

Mixed malignant mesoderm sarcomas (MLMS) are a rare subtype of malignant tumors with a myometrial origin. Usually, this pathology is diagnosed in menopausal women and has a fast evolution, with an unfavorable prognosis. This study analyzed data from the literature, which were subsequently correlated with a case of MLMS confirmed by classical histopathological examination and immunohistochemistry. It was performed total hysterectomy with bilateral adnexectomy. The clinical manifestations found in MLMS are the presence of a pelvic-abdominal tumor mass, accompanied by abdominal pressure, discomfort and vaginal bleeding. Imaging investigations such as pelvic ultrasound (US), computed tomography (CT) and magnetic resonance imaging (MRI) may suggest the diagnosis, but only the histopathological exam confirms it. From a macroscopic point of view, MLMS has a soft, gelatinous structure, compared to leiomyofibromas, with a hard and spiral structure. Another feature of MLMS is the infiltrative, irregular-looking tumor margin. The microscopic aspects of this malignant tumor are nuclear pleomorphism, necrosis of tumor cells, the presence of myxoid matrix, and variable mitotic activity. Due to the classic hematoxylin-eosin staining, the uterine smooth muscle has a leiomyomatosis structure, with the presence of multiple nodular formations suggestive for malignant tumor proliferation, probably of mesenchymal origin. We have shown that tumor cellularity is highly reactive to the anti-Vimentin antibody, an immunolabeled type III intermediate filament (IF) protein found in mesenchymal cells through special immunohistochemical techniques, demonstrating the mesenchymal origin of the tumor. The positivity of myocytes in the immunoreaction with the anti-alpha-actin antibody of smooth muscle (αSMA) shows that the tumor belongs to the myometrial structure. Tumor-transformed cells were genetically altered and mutated in the p53 tumor suppressor gene, thus escaping standard tissue control, aspects identified by immunolabeling with the anti-Ki67 antibody, which revealed cells in division. Tumor growth and development were supported by protein activation of cyclin-dependent kinase (CDK) and the presence of immunolabeled hematopoietic stem cells using the anti-cluster antibody of differentiation 117 (c-kit). The use of an anti-Desmin antibody in combination with anti- αSMA demonstrates the involvement of smooth muscle cells in tumor growth and development. The following microscopic features established the basis for the diagnosis of MLMS: irregular myometrial invasion the myxoid appearance that highlights rare cells dividing on sea fields. The following microscopic features laid the foundations for MLMS diagnosis: irregular myometrial invasion, rare mitosis on high power field (HPF: an average of 2.6 cells/×400 (±0.96 cells/×400) due to the presence of abundant myxoid matrix, rich in proteoglycans and glycosaminoglycans, especially hyaluronic acid, which offers a hypocellular appearance, but also through cell pleiomorphism. [ABSTRACT FROM AUTHOR]