Differential Diagnosis
- Single most likely diagnosis
- Acute pyelonephritis with renal vein thrombosis: The description of a diffusely enlarged left kidney with a heterogeneous T2 signal, striated appearance at the nephrographic phase, and no excretion of contrast in the delayed phase, along with multiple cortical non-enhancing areas and a low signal filling defect at the left renal vein, strongly suggests an infectious and thrombotic process. Acute pyelonephritis can lead to renal vein thrombosis, especially in the setting of severe infection.
- Other Likely diagnoses
- Severe hydronephrosis with infection: Although the primary description points towards pyelonephritis, severe hydronephrosis due to any cause (like obstructing stones) with superimposed infection could present similarly, especially if there's significant renal impairment and cortical damage.
- Renal infarction: This could be a consideration given the non-enhancing areas and the renal vein thrombosis, but the clinical context and the presence of infection signs (like the heterogeneous T2 signal suggestive of inflammation) make pyelonephritis a more likely primary diagnosis.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Renal cell carcinoma with renal vein thrombosis: Although less likely given the acute presentation and signs of infection, renal cell carcinoma can cause renal vein thrombosis. Missing this diagnosis could have significant implications for treatment and prognosis.
- Sepsis or systemic infection: The presence of acute pyelonephritis could be part of a more systemic infection. Identifying and treating the source of infection is crucial to prevent sepsis and its complications.
- Rare diagnoses
- Xanthogranulomatous pyelonephritis (XGP): A rare form of chronic pyelonephritis that could present with a similar appearance of a non-functioning kidney and might mimic other conditions like renal cell carcinoma. It's less likely given the acute presentation but should be considered in the differential for chronic or atypical cases.
- Renal lymphoma: Although rare, lymphoma can involve the kidney and cause non-enhancing lesions. The clinical context and additional imaging findings would be crucial in differentiating this from infectious or thrombotic processes.