Gorham-Stout disease: remission with sirolimus therapy.

Gorham-Stout disease (GSD) is a rare, non-hereditary, bone disease characterised by progressive osteolysis as a result of uncontrolled proliferation of endothelial-lined vessels replacing normal bone. We present a baby-girl with the classic radiological features of GSD and compatible clinical and histological findings, who developed progressive disease for over 2 years despite propranolol treatment. Propranolol treatment was stopped and sirolimus monotherapy started which resulted in near-complete resolution after 1 year, with no recurrence after discontinuation of treatment. This case not only illustrates the typical features of GSD on a variety of imaging modalities, but is also the first report showing stark contrast in response between propranolol and sirolimus treatment for GSD, highlighting how targeting lymphatic, rather than solely angiomatous, proliferation at the vascular endothelial growth factor-level may be a future direction.