RESUMO
The nature of the mononuclear stromal cells (MSCs) in giant cell tumor of bone (GCTB) has not been thoroughly investigated. The purpose of this study was to evaluate the degree and significance of myofibroblastic differentiation in 18 cases of GCTB by immunohistochemistry (IH) and/or electron microscopy (EM). All immunostained cases were found positive for smooth muscle actin (SMA) and/or muscle specific actin (MSA), most in 1-33% of the MSCs. Ultrastructurally, most MSCs were fibroblasts, and a significant number of cells displayed myofibroblastic differentiation. Myofibroblasts are an important component of MSCs in GCTB. The myofibroblastic population may be responsible in part for the production of matrix metalloproteinases (MMPs), which probably play a role in bone destruction, tumor aggression, and recurrence.
Assuntos
Biomarcadores Tumorais/análise , Neoplasias Ósseas , Diferenciação Celular , Tumor de Células Gigantes do Osso , Imuno-Histoquímica , Microscopia Eletrônica , Miofibroblastos , Células Estromais , Actinas/análise , Adolescente , Adulto , Biópsia , Neoplasias Ósseas/química , Neoplasias Ósseas/ultraestrutura , Feminino , Tumor de Células Gigantes do Osso/química , Tumor de Células Gigantes do Osso/ultraestrutura , Humanos , Masculino , Pessoa de Meia-Idade , Miofibroblastos/química , Miofibroblastos/ultraestrutura , Valor Preditivo dos Testes , Prognóstico , Células Estromais/química , Células Estromais/ultraestrutura , Adulto JovemRESUMO
Ultrastructural study of a case of benign lipoblastomatosis revealed a cellular spectrum which included undifferentiated mesenchymal cells, stellate myxoid cells, fibroblasts, lipoblasts, lipocytes and many intermediate forms. The uni- and multivacuolated fat cells contained membrane and non-membrane bound cytoplasmic vacuoles, predominatly of saturated lipid. Their cytoplasm also contained simple-structured mitochondria devoid of intramatrical or crystalloid bodies. The fine structure of the cellular components of lipoblastomatosis supports the concept that this is a neoplasm related to fetal white fat rather than to brown fat.