Spontaneous Renal Artery Pseudoaneurysm Causing Subcapsular Haematoma in the Setting of Acute Pyelonephritis: A Rare Clinical Nexus and Review of the Literature.
Spontaneous renal subcapsular haematoma caused by a renal artery pseudoaneurysm (RAP) arising in the context of acute pyelonephritis is an exceptionally rare event. This combination, infective arteriopathy leading to pseudoaneurysm formation with subcapsular haemorrhage, has seldom been reported and represents a clinically challenging diagnostic and therapeutic scenario. A 42-year-old woman with poorly controlled type 2 diabetes mellitus presented with right flank pain, fever and acute-on-chronic kidney disease. Imaging revealed bilateral pyelonephritis, a progressively enlarging right renal subcapsular haematoma (9.7 × 9.6 cm on computed tomography {CT} angiography) and a pseudoaneurysm arising from the inferior segmental branch of the right renal artery. She underwent successful selective right renal artery coil embolisation with subsequent clinical and biochemical improvement, without requiring nephrectomy. Infectious arteriopathy in the setting of acute pyelonephritis, particularly in immunocompromised diabetic patients, may culminate in mycotic pseudoaneurysm formation and spontaneous subcapsular haemorrhage. Early CT angiography and prompt endovascular intervention are pivotal to preserving the kidney and patient survival.