Histological study of osteoid osteoma's blood supply.

The osteoid osteoma is a painful lesion with a special predilection for the femur and tibia of young patients. Although the lesion has been described as richly innervated, its vascular supply has not been critically appraised to date in the pathology literature. To this end, we have undertaken a morphological study of 16 archival cases of osteoid osteoma, focusing primarily on the patterns of vascularization, utilizing traditional histological and immunohistochemical approaches. The study demonstrated that a prominent arterial and arteriolar blood supply was a constant finding within the various zones of soft tissues, skeletal muscle, and bone surrounding the nidus. It also showed that the caliber of the vessels underwent gradual attenuation throughout their centripetal course toward the nidus, where the vessels lost their muscularis as they merged into the capillary network of the nidus. Immunostaining with antibodies to neurofilament and S100 proteins revealed a pattern of innervation that was overall less exuberant than that described in some reports and that was virtually absent from the nidus. Taken together with data reported in the radiological literature, our findings lead us to wonder whether the osteoid osteoma may represent a response to the local stimulation of bony tissue by a primarily aberrant vasculature, a hypothesis that warrants further elucidation using state-of-the-art imaging approaches.