Differential Diagnosis

• Single most likely diagnosis
  • Nephrolithiasis: The presence of a 0.6 cm echogenic calculus in the left renal pelvis strongly suggests kidney stones, which is a common condition that can cause renal colic and other urinary symptoms. The absence of back pressure changes or focal discrete masses in both kidneys also supports this diagnosis.
• Other Likely diagnoses
  • Benign renal cysts: Although not explicitly mentioned, the presence of echogenic calculi and the normal size of the kidneys make it possible that there could be benign cysts, especially given the age of the patient (not specified).
  • Renal parenchymal disease: The slightly decreased size of the right kidney (11.7 x 5.3 x 4 cm) compared to the left kidney (12 x 6.2 x 6.3 cm) could suggest some form of renal parenchymal disease, such as chronic kidney disease or pyelonephritis, although there are no specific findings to support this.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Renal cell carcinoma: Although there are no documented focal lesions or discrete masses, it is essential to consider the possibility of renal cell carcinoma, especially if the patient has risk factors such as smoking, obesity, or family history.
  • Urothelial carcinoma: The presence of an echogenic calculus in the renal pelvis increases the risk of urothelial carcinoma, which can be asymptomatic in its early stages.
  • Obstructive uropathy: Although there are no documented back pressure changes, it is crucial to consider the possibility of obstructive uropathy, especially if the patient has symptoms such as flank pain or recurrent urinary tract infections.
• Rare diagnoses
  • Medullary sponge kidney: This rare condition is characterized by the presence of small cysts in the renal medulla and can increase the risk of kidney stones.
  • Renal tuberculosis: Although rare in developed countries, renal tuberculosis can cause renal damage and scarring, and should be considered in patients with risk factors such as immunosuppression or exposure to tuberculosis.