Immunohistochemical study of chondrolipoma:: Possible importance of transforming growth factor (TGF) -βs, latent TGF-β binding protein-1 (LTBP-1), and bone morphogenetic protein (BMP) for chondrogenesis in lipoma

To clarify the pathogenesis of chondrolipoma, we examined the expressions and localizations of TGF-beta1, -beta2, -beta3, BMP, and LTBP-1 in our rare case by immunohistochemical staining, and compared them with the staining patterns seen in normal human tracheal cartilage tissue and osteochondroma (controls). In the present case, there was weak TGF-beta1 expression in both lacuna and spindle cells around the cartilage, intense TGF-beta2 expression in both lacuna and spindle cells, and weak-to-moderate TGF-beta3 expression in the spindle cells. In lacuna cells, LTBP-1 was expressed moderately and BMP intensely. In contrast, the normal cartilage showed weak-to-moderate expressions of TGF-beta2, -beta3, and BMP in the lacuna cells with zero-to-weak TGF-beta2 and zero-to-moderate TGF-beta3 expressions in the spindle cells, while LTBP-1 was negative in both lacuna and spindle cells. Osteochondroma cases showed moderate-to-intense expressions of TGF-beta2, -beta3, and BMP in the lacuna cells, while LTBP-1 was positive in the lacuna cells and negative in the spindle cells. These findings suggest that the pattern of expression of TGF-betas, LTBP-1, and BMP may be important in the pathogenesis of chondrolipoma.