SYSTEMIC MASTOCYTOSIS: CLINICAL AND MORPHOLOGICAL ANALYSIS FIVE PATIENTS WITH A RARE DISEASE

The central component of the diagnosis of systemic mastocytosis is a morphological study of the affected organ, which is aimed at assessing the volume of tumor infiltration and the pattern of damage, which may reflect the biological properties of the tumor and the prognosis of the disease. The material for the study was trephination biopsies and bone marrow smears of 5 patients with systemic mastocytosis, aged 17 to 68 years. Paraffin sections were stained with hematoxylin and eosin, azure by Romanovsky, and immunohistochemistry was performed with antibodies to CD25 (Interleukin-2 receptor alpha chain), CD2 (T-cell surface antigen T11/Leu-5), CD117 (Mast/ stem cell growth factor receptor) and tryptase. Bone marrow smears stained by Romanovsky-Giemsa. At the time of the diagnosis, the 2016 WHO revision classification was used. In all patients, a tumor was detected in SM. In the indolent form, the bone marrow diseases were located singly and discretely, and they also formed perisinusoidal and perivascular clusters up to 10-15 cells, the total number of which did not exceed 15% of all nucleated cells. On the contrary, in case of smouldering form (n=2), a nodular lesion pattern was revealed, in which mas-tocytes formed para- and intertrabecular foci of various shapes with sizes up to 200-300 cells, with a total volume of tumor infiltration of 36 and 43%. In two patients with an aggressive form of the disease, the infiltration volume of CM was 65 and 75%, while in both cases diffuse growth was observed, with a subtotal substitution of most of the bone marrow lacunae, with narrowing of hemopoiesis, as well as the appearance of secondary dysplasia features in erythroid and megakaryocytic lineages. Thus, the clinical manifestations of the disease correlate with the volume and pattern of CM damage in SM.

systemic mastocytosis, smoldering systemic mastocytosis, bone marrow, mast cells