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Desmoplastic fibroma is a rare bone tumor with benign, locally aggressive, lytic behavior. Histologically, it is very similar to the more common and better known desmoid tumor. It can occur at any site in the skeleton but is most common in the mandible or in the long bones. We present two cases; the tumor was located in the proximal tip of the fibula in one case and in the proximal tip of the femur in the other. We describe the appearance of these lesions on CT and MRI. In both cases, the lesions were lytic, expansive, with a trabeculated appearance and internal septa, and without mineralized osseous matrix. At MRI, one of the tumors was very heterogeneous, with two differentiated areas on T2-weighted sequences: the upper zone was hypointense and the lower zone showed intermediate signal intensity. We also describe the behavior of the tumor after the administration of intravenous Gadolinium: the upper zone showed no significant enhancement and the lower showed significant enhancement in the early phase.

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RESUMEN

El fibroma desmoplásico es una neoplasia ósea poco frecuente, de comportamiento lítico, benigna y localmente agresiva. Histológicamente es muy similar al más frecuente y conocido tumor desmoide. Se puede presentar en cualquier punto del esqueleto, pero más frecuentemente en la mandíbula o en los huesos largos. Presentamos dos casos, localizados respectivamente en los extremos proximales del peroné y del fémur, y describimos su apariencia radiológica. Ambos casos se presentan como lesiones líticas, expansivas, de aspecto trabeculado y con septos internos, sin matriz ósea mineralizada. En el estudio mediante resonancia magnética (RM), uno de los tumores era muy heterogéneo,con dos áreas diferenciadas en la secuencia T2, la zona superior hipointensa y la inferior de intensidad intermedia. Describimos también su comportamiento tras la administración de gadolinio intravenoso: la zona superior sin un realce significativo y la inferior con un importante realce en fase precoz

Desmoplastic fibroma is a rare bone tumor with benign, locally aggressive, lytic behavior. Histologically, it is very similar to the more common and better known desmoid tumor. It can occur at any site in the skeleton but is most common in the mandible or in the long bones. We present two cases; the tumor was located in the proximal tip of the fibula in one case and in the proximal tip of the femur in the other. We describe the appearance of these lesions on CT and MRI. In both cases, the lesions were lytic, expansive, with a trabeculated appearance and internal septa, and without mineralized osseous matrix. At MRI, one of the tumors was very heterogeneous, with two differentiated areas on T2-weighted sequences: the upper zone was hypointense and the lower zone showed intermediate signal intensity. We also describe the behavior of the tumor after the administration of intravenous Gadolinium: the upper zone showed no significant enhancement and the lower showed significant enhancement in the early phase

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In the present work, we studied: (i) the effect of different doses of desferrioxamine and deferiprone on the proliferation of osteoblasts and the possible role of iron in this; and (ii) the effect of both chelators on the metabolic activity of these cells, using the quantification of alkaline phosphatase as an enzymatic marker of cellular activity or differentiation. Cellular proliferation was investigated at different concentrations of deferiprone and desferrioxamine, and the effect of the addition of iron citrate on this proliferation was measured. The production of alkaline phosphatase after incubation with deferiprone (150 and 300 microM) and desferrioxamine (20 and 100 microM) was also studied. Cellular proliferation was completely inhibited with 100 microM of desferrioxamine and 300 microM of deferiprone. In both cases, this effect was corrected by means of co-incubation with iron citrate. In the second phase, using the same dose that inhibited the proliferation, it was observed that after 24 h, both chelators slightly decreased alkaline phosphatase activity, while at 48 and 96 h they increased alkaline phosphatase activity. These results demonstrate that both desferrioxamine and deferiprone inhibit the proliferation of the osteoblast-like cell line MG-63; the effect seems to be related to the chelation of some fraction of available iron. In spite of the effect on bone cell proliferation, the chelators do not impair cellular activity.

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