Given an abstract, generate a keyword (a noun phrase) that best describes the focus or contribution of the paper. Such keywords can be directly from the given abstract or outside it.

Abstract: Fistula or deep sinus formation as a complication of xanthogranulomatous pyelonephritis (XPN) has not been described previously in the British literature. We present the clinicopathological features of one case of a nephrodiaphragmatic sinus complicating XPN, and three cases of nephrocolic fistula, including the first recorded case of fistula in childhood XPN. The detailed clinical, radiological and pathological features of XPN and its complications are reviewed. Total nephrectomy, together with primary excision of sinuses or fistulae, is the treatment of choice.
Adult

Abstract: Four patients with chronic subdural hematomas, all of which resolved spontaneously, were followed from the time of injury to resolution of the chronic subdural hematoma. Periodic computed tomographic (CT) scans showed spontaneous resolution 78, 174, 231, and 326 days after the development of the chronic subdural hematoma, respectively. Features of the CT scans and a possible mechanism of spontaneous resolution are discussed.
Adult

Abstract: Protein S deficiency is inherited as an autosomal dominant trait. Heterozygotes with a reduction of 50% in the plasma protein S concentration are at risk for the development of venous thromboembolism, often occurring at an early age without an apparent cause. In the majority of the patients thrombosis is restricted to the superficial or deep venous system of the legs. In this case report we describe the presence of mesenteric vein thrombosis in a 30-yr-old man with hereditary protein S deficiency. In his family protein S deficiency was also recognized in his mother, brother, and niece. Both his mother and brother had a history of thrombotic disease.
Adult