Hemangiopericytoma: causes, symptoms, diagnosis, treatment

Hemangiopericytoma develops from capillary vessels and is most often localized on the scalp and extremities, in the subcutaneous fat layer and skeletal muscles of the lower extremities.

Clinically manifests itself as tuberous nodular formations, usually solitary, of varying size and density, covered with unchanged or bluish-red skin. The tumor grows relatively slowly, can ulcerate, give infiltrative growth and metastasize. It can develop at any age, but more often in people over 40 years of age. In children, it is more severe.

Pathomorphology of hemangiopericytoma. The tumor is based on newly formed capillaries with slit-like, barely noticeable lumens. The tumor cells are approximately identical, resemble pericytes in appearance, have weakly eosinophilic cytoplasm containing glycogen and round or oval nuclei filled with euchromatin, with a distinct nuclear membrane. Mitoses are rare. When sections are treated with silver salts, argyrophilic fibers are found in the tumor, surrounding the lumens of the vessels and separating the endothelial elements from the proliferating pericytes. In some cases, with such treatment, each tumor cell is surrounded by a thin argyrophilic network, which is of diagnostic value. Proliferation of tumor cells is observed around the vessels, mainly in a cuff-like manner.

In hemangiopericytoma with malignant potential, as in metastases, the cells are usually polymorphic, with spindle-shaped forms predominating among them; a large number of mitoses are noted. The tumor stroma is scanty, the argyrophilic network, although present, is without a characteristic location, which complicates diagnosis.

Histogenesis of hemangiopericytoma. The tumor develops from pericytes located in the walls of capillaries and venules. Electron microscopic examination of hemangiopericytoma shows that in some cases it consists of poorly differentiated cells surrounded not by a basal membrane, but by a material that only resembles it. Other authors have found typical basal membranes in this tumor. The same author found cytoplasmic filaments and dense bodies associated with them in the cytoplasm of tumor elements. Tumor pericytes sometimes contain bundles of muscle cells and transitional forms between them.

Hemangiopericytoma is differentiated primarily from glomus angioma, which at first glance resembles pericytoma. However, the perithelial elements of the latter are located mainly around the vessels, while glomus cells are in the walls of the arterial canals. In addition, hemangiopericytoma can be localized in any part of the body, while glomus angioma is predominantly on the fingertips. Hemangiopericytoma can be distinguished from other tumors (hemangioendothelioma, etc.) by the presence of argyrophilic fibers in it.

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