Route of infection in Tubercular Pyelonephritis-

Tuberculous Pyelonephritis Tuberculosis of the kidney occurs due to hematogenous spread of infection from another site, most often from the lungs. Less commonly, may result from ascending infection from tuberculosis of the genitourinary system such as from epididymis or Fallopian tubes. The renal lesions in tuberculosis may be in the form of tuberculous pyelonephritis or appear as multiple miliary tubercles. MORPHOLOGIC FEATURES. Grossly, the lesions in tuberculous pyelonephritis are often bilateral, usually involving the medulla with the replacement of the papillae by caseous tissue. Ref: Textbook of pathology Harsh Mohan 6th edition page 684