Klippel-Trenaunay syndrome (KTS) is characterized by a cutaneous vascular nevus of the involved extremity, as well as bone and soft tissue hypertrophy of the extremity and venous malformations. We present the case of a 52-year-old man with a femoral fracture and a history of haemangiomas, limb bone hypertrophy and varicosity. The patient was finally diagnosed with KTS and treated in mini-invasive surgery by endomedullary fracture nailing in general anaesthesia. Clinical management was particularly demanding, not only because of the need to monitor the risk of haemorrhage and thrombosis but also because of the onset of a rare picture of neuropathic pain with hyperalgesia and allodynia, never previously reported in patients affected by KTS, that required the administration of major opioid drugs. According to our knowledge, this is the second case of KTS managed for femoral fracture. Unlike the previous report in literature, in this case a severe disabling neuropathic pain complicated the clinical management.