Аннотация:Infantile myofibroma (myofibromatosis) (IM) is a mesenchymal tumor of soft tissues of the head, extremities and trunk. It is characterized by relapse-free infiltrative growth. It consists of neoplastic myofibroblasts at varying stage of cell differentiation which form multi-structured tumor zones. IM’s morphological differentiated diagnosis is established vis-a-vis other varieties of tumor and reactive nodular structures of fibroblasts, primarily, infantile hemangiopericytomas and desmoid fibromatosis. Immunohistological and ultrastructural examination of tumor is required for making correct diagnosis of IM.