[Rhabdomyosarcomas: structural distribution and analysis of an immunohistochemical profile]. / Rabdomiosarkomy: strukturnoe raspredelenie i analiz immunogistokhimicheskogo profilya.

Rhabdomyosarcoma (RMS) is a malignant soft tissue tumor originating from primitive mesenchymal cells, which is most common in children. OBJECTIVE: To qualitatively and quantitatively assess the expression of myogenic transcription factors on a large sample, to identify potential phenotypic differences, and to estimate the distribution and frequency of aberrant markers, such as ALK, PAX5, WT1, PCK, CAM5.2, SIX1, and Synaptophysin. MATERIAL AND METHODS: The investigation included 202 tumor tissue samples. Five tissue microarrays were assembled from the obtained material for subsequent histological and immunohistochemical studies. RESULTS: Embryonal RMS (ERMS) was diagnosed in 103 cases; alveolar RMS (ARMS) was detected in 80; spindle-cell/sclerosing RMS (SRMS) was found in 16 cases; epithelioid RMS (EpiRMS) was diagnosed in 2 patients. The expression of Myogenin and MyoD1 was detected in all the examined RMS tissue samples. ARMS was more characterized by staining at 1+ and 2+ intensities; at the same time, more than 50% of ERMS, SRMS, and EpiRMS cases showed staining at 1+ intensity. ALK expression was investigated using the D5F3 and p80 clones. The D5F3 clone displayed a higher staining intensity than the p80 clone (p<0.05). The expression of PAX5 was observed in 13 of 75 ARMS cases. That of WT1 and SIX1 was found in all RMS groups. CONCLUSION: The morphological diagnosis of RMS requires a careful assessment of all of the above factors, especially taking into account the variability in the expression of myogenic transcription factors and the high level of phenotypic aberration.

[Extrarenal rhabdoid tumor: A review of literature and a report of cases with atypical morphology]. / Ékstrarenal'naia rabdoidnaia opukhol'. Obzor literatury i opisanie sluchaev s netipichnoi morfologiei.

Extrarenal extracranial rhabdoid tumor (EERT) is a rare malignant pediatric tumor characterized by extremely aggressive behavior, rapid metastatic spread, low survival rates, and no targeted therapy. The morphological diagnosis of classical cases of EERT is not difficult and it is based on its characteristic histologic pattern and immunohistochemical findings in a relatively short time, which allows one to immediately initiate therapy. The paper describes two cases of ERRT in the complete absence of classical rhabdoid morphology, as revealed by light microscopy when the material was primarily assessed. The final diagnostic search could establish a diagnosis of EERT in both cases on the basis of immunohistochemical findings.

[Osteochondroma in children and adolescents].

Osteochondroma is called a benign cartilage-forming tumor arising from an aberrant subperiosteal cartilage. Multiple osteochondromas syndrome (MOS) is an autosomal dominant disease, the basis for which is mutations in the EXT (EXT1 or EXT2) genes. Osteochondroma is one of the most common benign bone tumors. According to the WHO data, it is detectable in 35% of benign bone tumors and 8% of all surgically removed bone tumors. A total of 491 cases of bone tumors were analyzed in the children and adolescents diagnosed at the Department of Pathoanatomy, Russian Children's Clinical Hospital, Moscow, in 2009 to 2014. All the patients with osteochondroma were divided into 2 groups: 1) sporadic cases (n = 63) and 2) tumors included in MOS (n = 33). Both groups showed a preponderance of boys (39 boys and 24 girls in Group 1 and 21 boys and 12 girls in Group 2). Clinical, radiological, and morphological criteria for the diagnosis and differential diagnosis of osteochondromas in children and adolescents are given.

[Classical osteosarcoma in children and adolescent].

Classical osteosarcoma is one of the most common primary malignant bone tumors in children and adolescents. It more frequently occurs in the areas of the highest growth plate proliferation: limb long bones particularly in the distal femur (30%), proximal tibia (15%), and proximal humerus (15%). In the long bones, the tumor is located usually in the metaphysis (90%), less frequently in the diaphysis (9%), and very rarely in the epiphysis. This paper considers the clinical, radiological, and histological diagnosis, and prognosis in this pathology.