Ultrastructural evidence for presenсe of gap junctions in rare case of pleomorphic xanthoastrocytoma.

The phenomenon of unstable expression of gap junction's proteins connexins remains a "visiting card" of astrocytic tumors with various degrees of malignancy. At the same time, it stays unclear what is detected by the positive expression of connexins in astrocytic tumors: gap junctions, hemi-channels, or connexin proteins in cytosol. In the present work, for the first time, we demonstrate an ultrastructural evidence of gap junctions in pleomorphic xanthoastrocytoma, a rare primary brain tumor, the intercellular characteristics of which are poorly studied and remain very discursive and controversial. The primary tumor mass was resected during craniotomy from a 57-old patient diagnosed with pleomorphic xanthoastrocytoma Grade II based on the histopathological analysis. The immunohistochemical study was conducted with primary antibodies: Neurofilament, Myelin basic protein, Glial fibrillary acidic protein, and Synaptophysin. For electron microscopic examination fragments of tumor tissue were fixed in a glutaraldehyde, postfixed in a 1% OsO4, dehydrated and embedded into resin. After the detailed clinical, histological, and immunohistochemical study we revealed some ultrastructural characteristics of the tumor, as well as the first evidence of direct intercellular connection between the tumor cells via gap junctions. Regularly arranged gap junctions connected the somas of xanthastrocytes with dark cytoplasm containing lipid drops. Besides the localization between the cell bodies, from one to several gap junctions were found between the branches of xanthoastrocytoma in tumor intercellular space in close proximity to tumor cell. Our results may indicate gap junctions as a possible structure for intercellular communication between pleomorphic xanthoastrocytoma cells.

Description of the rare localization of Dirofilaria repens in human in the right inguinal lymph node.

D. repens is the causative agent of subcutaneous dirofilariasis in canine animals. In recent years, human invasion by this vector-borne helminthiasis has been recorded in many countries with temperate climate, but the localization of this helminth in the cavities of the human body is extremely rare. Cases of atypical localization of D. repens are described in the organs of the chest, cervical lymph node, in the spermatic cord and epididymis. It is usually requires differential diagnosis with neoplastic or metastatic processes. We report a case of the detection of Dirofilaria repens in the right inguinal lymph node in a 56-year-old woman. Helminth was identified by parasitological and molecular biological methods. A morphological study of cross sections of the nematode in histological preparations and molecular biological method, the polymerase chain reaction (PCR) of scrapings of histological material, were used in parallel.