CD105/endoglin expression in Gorham disease of bone
Gorham disease is a rare pathological condition characterised by a proliferation of vascular channels of haematic and lymphatic origin in bone and adjacent soft tissues, which results in a progressive destruction of the involved bone segment. To evaluate expression of the vascular endothelial cell marker CD105/endoglin in Gorham disease of bone. An immunohistochemical analysis was conducted on four cases of Gorham disease of bone, and for comparison on eight cases of conventional haemangioma of bone and on normal fetal and adult bone tissue specimens. Diffuse and intense immunostaining of endothelial cells for CD105 was observed in the specimens of fetal bone in areas undergoing ossification and in the growth plate of young adults. In medullary bone, CD105 positivity was limited to sinusoids of haemopoietic marrow, while endothelial cells of capillaries and small arterioles and venules within fatty marrow were either negative or showed weak immunostaining. The mean percentage of positive vessels in Gorham disease was significantly higher than in osseous haemangioma (58.9 (SEM 14.9) vs 17.2 (SEM 12.0); p = 0.03, Mann-Whitney U test). A significant direct correlation was observed between the proliferative activity assessed by MIB-1 immunostaining, and the percentage of CD105 positive vessels in the entire series (r = 0.681; p = 0.01). Data indicate that the phenotype of proliferating endothelial cells of Gorham disease is similar to that of the endothelial lining of vessels of metabolically active bone characterised by high expression of CD105, while that of conventional haemangioma is more similar to that of metabolically quiescent bone tissue, such as fatty marrow, with low levels of expression of CD105. This may have potential therapeutic and diagnostic applications.