Sirolimus‐associated lymphoedema: eight new cases and a proposed mechanism

Summary Sirolimus, an inhibitor of the mammalian target of rapamycin (mTOR), is increasingly used as an agent for post‐transplant immunosuppression and the treatment of solid organ and haematological malignancies and hamartomas. Its advantages include a lack of nephrotoxicity and a lower incidence of nonmelanoma skin cancers; adverse effects include delayed wound healing, increased lymphocoele formation and rarely lymphoedema. We report a series of eight cases of severe, sustained, unilateral and bilateral lymphoedema in patients receiving sirolimus for post‐transplant immunosuppression, classify their lymphoscintigraphy findings and propose a mechanism of aetiology based on the interaction of mTOR with key mediators of lymphangiogenesis.