Differential Diagnosis for Right-Sided Flank Pain

The patient's presentation of right-sided flank pain, exacerbated by movement and without significant past medical history, suggests several potential diagnoses. These can be categorized as follows:

• Single Most Likely Diagnosis

  • Musculoskeletal strain: Given the exacerbation of pain with movement, rolling over, and sitting, and the absence of other systemic symptoms, a musculoskeletal strain is a plausible explanation. The patient's age and the description of the pain as an ache also support this diagnosis.

• Other Likely Diagnoses

  • Kidney stones (nephrolithiasis): Although the patient denies urinary symptoms, kidney stones can sometimes present with flank pain alone, especially if they are not obstructing the ureter. The pain's exacerbation with movement could be consistent with a stone moving within the urinary tract.
  • Degenerative spinal disease: At 72 years old, degenerative changes in the spine could be contributing to the patient's flank pain, especially if the pain is referred from the spine due to nerve root irritation.
  • Constipation: While the patient attributes her constipation to iron supplementation and notes improvement with Colace, severe constipation can cause significant abdominal and flank discomfort.

• Do Not Miss Diagnoses

  • Pulmonary embolism: Although less common, pulmonary embolism can present with flank or chest pain and is a life-threatening condition that must be considered, especially in the absence of a clear alternative diagnosis.
  • Aortic dissection: This is a medical emergency that can present with severe, tearing chest or back pain, which might be perceived as flank pain. The absence of abdominal pain and urinary symptoms does not rule out this diagnosis.
  • Pyelonephritis or perinephric abscess: Despite the denial of fever and urinary symptoms, these conditions can occasionally present atypically, especially in older adults, and are critical to diagnose promptly.

• Rare Diagnoses

  • Pheochromocytoma: A rare tumor of the adrenal gland that can cause episodic pain, among other symptoms, though it is less likely given the lack of other characteristic symptoms like hypertension or palpitations.
  • Retroperitoneal fibrosis: A rare condition characterized by the proliferation of fibrous tissue in the retroperitoneum, which can cause flank pain and obstructive uropathy, though it would be unusual without other symptoms or signs.
  • Spinal tumors: Tumors of the spine, either primary or metastatic, can cause flank pain due to local invasion or compression of nerve roots, but would be less common without a history of cancer or significant neurological symptoms.