Apoptosis and expression of Bax/Bcl-2 proteins in pyogenic granuloma: a comparative study with granulation tissue and capillary hemangioma.

BACKGROUND

Pyogenic granuloma (PG) has been regarded as a florid expression of granulation tissue (GT) proliferation and shows distinct biological behavior compared to conventional GT. PG has not been examined from a standpoint of apoptosis.

METHODS

PG (15 cases), GT (14 cases) and capillary hemangioma (CH, 8 cases) were compared using in situ 3'-tailing reaction (ISTR), a histochemical method for identifying apoptotic cells, and immunohistochemistry for Ki-67, Bcl-2 and Bax proteins, in order to clarify and involvement of apoptosis in the difference of biological characteristics between PG and GT.

RESULTS

PG showed significantly lower ISTR-labeling indices than GT and CH and more frequent Bcl-2/Bax expression than GT, whereas Ki-67-labeling indices were variable from case to case and did not show any significant differences among any groups.

CONCLUSIONS

It is consequently suggested that the low apoptotic rate in PG is closely related to its characteristic rapid growth and is regulated by Bcl-2 family proteins.