What is the diagnosis and management for calcifications over the lower pole of each kidney, right iliac bone, and left sacral ala?

Diagnosis and Management of Calcifications in the Lower Pole of Kidneys, Right Iliac Bone, and Left Sacral Ala

The calcifications over the lower pole of each kidney, right iliac bone, and left sacral ala most likely represent nephrolithiasis (kidney stones) and bone insufficiency fractures, requiring targeted imaging and appropriate management based on clinical presentation.

Kidney Calcifications Assessment

Diagnostic Approach

• Kidney calcifications should be evaluated with unenhanced helical CT as the first-line imaging modality, which is the gold standard for detecting urolithiasis with sensitivity up to 97% 1
• Conventional radiographs in two planes should be the initial investigation for any suspected bone lesion, followed by MRI if malignancy cannot be excluded 1
• For kidney calcifications specifically, the location in the lower pole suggests renal calculi, which require assessment of size and potential for obstruction 1

Classification and Significance

• Calcifications in the lower pole of kidneys are most commonly renal calculi but could also represent:
  • Nephrocalcinosis (cortical or medullary) 1
  • Calcified cysts (which typically have thin, peripheral "eggshell" appearance) 2, 3
  • Parenchymal stones (benign calcified renal masses) 4

Management of Kidney Calcifications

• For asymptomatic caliceal stones, active surveillance is appropriate for stones up to 15 mm 1
• For lower pole stones <10 mm, first-line treatment options include flexible ureteroscopy (fURS) or shock wave lithotripsy (SWL) 1
• For lower pole stones 10-20 mm, fURS and percutaneous nephrolithotomy (PCNL) are the suggested options 1
• Follow-up imaging is mandatory if conservative management is chosen 1

Bone Calcifications Assessment

Diagnostic Approach for Bone Calcifications

• Calcifications in the right iliac bone and left sacral ala should be evaluated with:
  • Plain radiographs as initial imaging 1
  • MRI as the next imaging study if radiographs are inconclusive, particularly for suspected insufficiency fractures 1
• Bone scintigraphy (nuclear medicine bone scan) may be useful but has limitations in elderly or osteoporotic patients 1

Likely Diagnosis and Management

• Calcifications in the iliac bone and sacral ala most commonly represent insufficiency fractures in patients with abnormal bone (osteoporosis, prior radiation, etc.) 1
• Sacral insufficiency fractures often present with intractable lower back or pelvic pain, exacerbated by weight bearing 1
• The "Honda" or "H" sign on bone scintigraphy has a positive predictive value of 94% for sacral insufficiency fracture 1

Differential Diagnosis Considerations

• Primary hyperparathyroidism should be considered when both renal and bone calcifications are present, as it increases risk of nephrolithiasis (7% prevalence vs 1.6% in general population) 5
• Vascular calcifications may mimic bone lesions and should be distinguished using contrast-enhanced imaging 1
• Calciphylaxis is a rare but devastating condition associated with end-stage renal disease that can present with extensive soft tissue and vascular calcifications 6

Recommended Management Algorithm

1. Initial Evaluation:

   • Unenhanced CT of abdomen/pelvis to characterize kidney calcifications 1
   • Plain radiographs of pelvis and sacrum 1
   • Laboratory assessment including calcium, phosphate, PTH, alkaline phosphatase, and renal function 1

2. For Kidney Calcifications:

   • If stones <10 mm and asymptomatic: observation with follow-up imaging 1
   • If stones >10 mm or symptomatic: consider fURS or SWL based on stone size 1
   • Evaluate for signs of obstruction that would require more urgent intervention 1

3. For Bone Calcifications:

   • If insufficiency fractures confirmed: pain management and treatment of underlying bone disease 1
   • Consider bone mineral density testing to assess for osteoporosis 1
   • Rule out malignancy if imaging features are concerning (pure central calcification often indicates malignancy) 2

4. Follow-up:

   • Periodic imaging to monitor kidney stones for growth or new stone formation 1
   • Metabolic evaluation if recurrent kidney stones are present 1
   • Bone healing assessment for insufficiency fractures 1

Important Considerations and Pitfalls

• The combination of renal and bone calcifications should prompt investigation for systemic disorders affecting calcium metabolism 1, 5
• Vascular calcifications can mimic ureteral stones; contrast-enhanced CT can help differentiate between them 1
• Insufficiency fractures in the sacrum may be missed on plain radiographs due to overlying bowel gas and soft tissue; MRI is more sensitive 1
• Avoid unnecessary radiation exposure by using appropriate imaging protocols and considering ultrasound for follow-up of kidney stones when possible 1