Till date, the exact etiology and nature of the disease process remains undetermined. The pathologic process is the replacement of normal bone by an aggressively expanding nonneoplastic vascular tissue[5,6] similar to a hemangioma or lymphangioma.
Presence of wide capillary-like vessels is the main feature of the disease. It is likely that the blood flow through these vessels is slow, which produces local hypoxia and lowering of the pH, favoring the activity of various hydrolytic enzymes.[4] Strong activity of acid phosphatase and leucine aminopeptidase in mononuclear perivascular cells which are in contact with bone indicates that these cells are important in the process of osseous resorption.[7]
Active hyperemia, changes in local pH and mechanical forces promote bone resorption. Gorham and Stout hypothesized that trauma may trigger the process by stimulating the production of vascular granulation tissue and that “osteoclastosis” is not necessary.[1] Whereas, Devlin et al., have suggested that bone resorption in patients with Gorham disease is due to enhanced osteoclast activity and interleukin 6 plays a role in the increased resorption of bone.[6] Evidence that osteolysis is due to an increased number of stimulated osteoclasts was presented by Moller et al.,[8] Cellular and humoral mechanisms of osteoclast formation and bone resorption was reported by Hirayama et al., which suggested that the increase in osteoclast is not due to an increase in the number of circulating osteoclast precursors, but rather is due to an increase in the sensitivity of these precursors to humoral factors, which promote osteoclast formation and bone resorption.[9] It has also been suggested that thyroid C cells and calcitonin may play an important role in the pathogenesis of Gorham's disease.[10]