Cystic fibrosis related diabetes (CFRD) is a rare pathology that combines genetically determined systemicity with damage to the exocrine glands, which leads to early manifestations of the disease, a clear exacerbation and chronicity of the process, with possible complications in bone remodeling with the occurrence of malignant tumors. Purpose - to acquaint practitioners with the peculiarities of manifestations, diagnosis and course of chondroblastic osteosarcoma in a child with CFRD. Features of the clinical course and differential diagnosis are described and given osteosarcoma of the proximal part of the left tibia against the background of CFRD in a child. The main diagnostic value of history, clinical picture, laboratory, instrumental, immunohistochemical and microscopic research methods was highlighted, in particular, a biopsy of this tumor. Microscopic examination of tissue biopsy revealed alternating areas of atypical cartilaginous tissue corresponding to the structure of chondrosarcoma 1-2 cm, solid proliferates of atypical fibroblast-like cells and areas of atypical and fibroblastic tissue containing elements of atypical osteogenesis. Periosteally - randomly oriented bone fragments at the place of the cortical plate, as well as impressions of the lower metaphysis of the thigh and the upper metaphysis of the tibia, near the knee joint. The immunohistochemical examination showed a clear differential diagnosis of the existing CD99-positive tumor cells (DAKO, clone 12E7). Some cells were positive for SATB2 (Cell Marque, clone EP281); tumor cells were negative for S-100 - SOX-10. The histological picture and immunophenotype of the tumor cells correspond to chondroblastic osteosarcoma. Osteosarcoma with genetic, metabolic and aplastic features developing in the setting of a comorbid background significantly complicates diagnosis and requires certain changes in the treatment tactics of CFRD (correction of prophylactic and basic therapy, metabolic and toxic disorders, including those caused by chemotherapy). The research was carried out in accordance with the principles of the Helsinki Declaration. The informed consent of the patient was obtained for conducting the studies. No conflict of interests was declared by the authors.

Annotation. Features of the clinical course and differential diagnosis of hereditary thrombocytopenia, characterized by the development of pancytopenia in childhood, are described. It was found that the main manifestation of this pathology is hemorrhagic syndrome, accompanied by the presence of polymorphic, polychrome, asymmetric hemorrhagic rashes, frequent bleeding from the mucous membranes. The Mpl gene (1p34) was sequestered to confirm the diagnosis and establish the genomic mutation. Complex diagnosis of this disease requires a comprehensive and interdisciplinary approach involving a coordinated team of hematologists, geneticists, immunologists, neurosurgeons and ophthalmologists.

Crohn’s disease (CD) is a chronic relapsing disease characterized by transmural granulomatous-ulcerative inflammation affecting some or all parts of the gastrointestinal tract. Purpose - to acquaint practicing doctors with the features of the manifestations, differential diagnosis and course of CD in children. The features of the differential diagnosis and clinical course of CD are given. The basic diagnostic value of complaints, anamnesis, clinical picture, laboratory and instrumental methods of research, histological study of a biopsy of the cecum and appendix is highlighted. Microscopic examination of the cecum biopsy revealed the presence of a corrugated surface of the mucous membrane of the large intestine with focally slightly disturbed histoarchitectonics: crypts of various sizes and shapes, some with an unevenly expanded lumen. The cellular composition of the crypts is represented by colonocytes and goblet cells with reduced mucus formation, the presence of single crypt abscesses. Own plate with foci of fibrosis, unevenly infiltrated with lymphocytes, plasma cells, segmented nuclear neutrophils, eosinophils, basal plasmacytosis is noted. The muscle plate is slightly thickened, with uneven full blood vessels, infiltrated with lymphocytes, plasma cells, segmented neutrophils, with the presence of single lymphoid follicles (“incomplete granulomas”). The morphological picture may correspond to CD (taking into account endoscopic, clinical, anamnestic and other data). The research was carried out in accordance with the principles of the Declaration of Helsinki. Informed consent of the child’s parents was obtained for the research. No conflict of interests was declared by the authors.

Annotation. Peculiarities of clinical course and differential diagnosis of multisystem inflammatory syndrome (MIS-C) in children with coronavirus infection are described. The main features of this disease are long-term fever, multiorgan dysfunction, laboratory signs of inflammation and positive tests for SARS-CoV-2 (polymerase chain reaction using reverse transcription (RT-PCR), antigen test or positive serological test). The criteria of the World Health Organization (WHO) and the US Centers for Disease Control and Prevention (CDC) are used to confirm the MIS-C diagnosis.