41 year-old individual with increased frequency and dysuria. 1st Image: Unenhanced, coronal reformatted CT scan of abdomen 2nd Image: Axial CT scan of abdomen What is the most likely diagnosis?

Ankylosing spondylitis Medullary sponge kidney Xanthogranulomatous pyelonephritis Spina bifida Renal tuberculosis *This image based case is from Docplexus Editorial Team for educative purpose only Source: LearningRadiology