Differential Diagnosis for Left-Sided Back Pain

The patient presents with left-sided back pain, a history of recurrent renal calculi, and previous renal colic. The following differential diagnoses are considered:

• Single Most Likely Diagnosis

  • Renal Colic due to Kidney Stones: The patient's history of bilateral renal calculi, previous renal colic, and the current presentation of sharp, constant, deep pain in the left flank, which worsens with movement and improves when upright, are all consistent with renal colic. The presence of non-obstructing calculi in the left renal collecting system on the CT renal tract supports this diagnosis.

• Other Likely Diagnoses

  • Musculoskeletal Back Pain: Given the patient's sedentary work as an IT professional, musculoskeletal back pain is a possible diagnosis. However, the absence of spinal tenderness, paraspinal muscle tenderness, and the specific characteristics of the pain (worsening with lying down and improving when upright) make this less likely.
  • Pyelonephritis or Upper Urinary Tract Infection: Although the patient does not currently have fever, nausea, or vomiting, and the abdomen is soft and non-tender, a urinary tract infection could still be considered, especially with a history of renal calculi. However, the lack of systemic symptoms and the absence of organomegaly or masses make this less likely at present.

• Do Not Miss Diagnoses

  • Appendicitis: Although the pain is primarily in the left flank and not typical for appendicitis, which usually presents with right lower quadrant pain, atypical presentations can occur, especially in retrocecal appendicitis. The absence of abdominal tenderness and normal bowel sounds decreases the likelihood but does not rule it out entirely.
  • Pulmonary Embolism: This is a critical diagnosis not to miss, as it can present with sudden onset of pain that worsens with movement. However, the patient's presentation and the lack of respiratory symptoms (e.g., shortness of breath, chest pain) make this less likely.
  • Aortic Dissection: This is a life-threatening condition that can present with severe, tearing back pain. The patient's pain description and the absence of hypertension or other suggestive signs decrease the likelihood, but it remains a diagnosis that should be considered, especially in patients with risk factors.

• Rare Diagnoses

  • Pheochromocytoma: A rare tumor of the adrenal gland that can cause episodic back pain, among other symptoms like hypertension and palpitations. The patient's presentation does not strongly suggest this diagnosis, but it could be considered in the differential for unexplained or recurrent episodes of severe back pain.
  • Spinal Tumors or Infections: These can cause back pain that worsens with movement and can have a variety of other symptoms depending on the location and nature of the lesion. The absence of neurological symptoms and the negative back examination make these less likely, but they remain in the differential for persistent or unexplained back pain.