What is the treatment approach for a patient with 2 bone lesions in the pelvis and ribs?

Treatment Approach for 2 Bone Lesions in Pelvis and Ribs

The immediate priority is to determine whether these lesions represent multiple myeloma, metastatic disease, or primary bone tumors through urgent diagnostic workup including serum/urine protein studies, skeletal imaging, and bone marrow examination before initiating treatment. 1

Initial Diagnostic Algorithm

Step 1: Rule Out Multiple Myeloma First

Multiple myeloma is the most common malignancy causing multiple bone lesions in the pelvis and ribs, and must be excluded immediately:

• Obtain serum protein electrophoresis (SPEP), immunofixation, and serum free light chain assay with kappa/lambda ratio to detect monoclonal protein 1, 2
• Perform 24-hour urine collection for total protein, urine protein electrophoresis (UPEP), and urine immunofixation to detect Bence Jones proteins 1, 3
• Measure serum beta-2 microglobulin, LDH, calcium, creatinine, and complete blood count to assess for end-organ damage and staging 1
• Bone marrow aspiration and biopsy with flow cytometry and FISH (probes for chromosome 17p13, t(4;14), and t(14;16)) are mandatory if plasma cell dyscrasia is suspected 1

Step 2: Complete Skeletal Imaging

• Whole-body low-dose CT scan is now the preferred method over plain skeletal survey for detecting bone lesions, as it identifies up to 60% more relevant findings and changes treatment in up to 20% of patients 1
• Note: Skull and rib lesions are better detected by focused plain radiographs than by whole-body CT or MRI 1
• FDG-PET/CT or MRI should be considered if CT is inconclusive, for nonsecretory myeloma, or to evaluate extramedullary disease 1

Step 3: Rule Out Metastatic Disease (Age-Dependent)

• In patients ≥40 years old, metastatic disease and myeloma are statistically more common than primary bone sarcomas 1
• Obtain CT chest/abdomen/pelvis to search for primary malignancy (lung, breast, prostate, kidney, thyroid) 1
• Perform mammogram in women and PSA in men as clinically indicated 1

Step 4: Consider Primary Bone Tumors

If myeloma and metastases are excluded:

• Plain radiographs of affected areas remain the cornerstone for characterizing primary bone tumors by assessing margins, periosteal reaction, and matrix mineralization 1, 4
• Biopsy must be performed at a specialized sarcoma center by the surgical team that will perform definitive resection, as biopsy tract contamination affects local recurrence risk 1
• Core needle biopsy under imaging guidance is appropriate in most cases, but the approach must be planned to allow en bloc resection of the biopsy tract 1

Treatment Based on Diagnosis

If Multiple Myeloma is Confirmed

For transplant-eligible patients:

• Initiate triple-agent induction therapy with bortezomib, lenalidomide, and dexamethasone followed by autologous stem cell transplantation 3
• High-dose melphalan 200 mg/m² is the preferred preparative regimen prior to transplantation 3

For all myeloma patients with bone lesions:

• Administer zoledronic acid 4 mg IV every 3-4 weeks (dose-adjusted for creatinine clearance <60 mL/min) to reduce skeletal events 5
• Provide oral calcium 500 mg daily and vitamin D 400 IU daily as supportive care 5
• Monitor serum creatinine before each zoledronic acid dose and withhold treatment if creatinine increases by 0.5 mg/dL (normal baseline) or 1.0 mg/dL (abnormal baseline) 5

If Primary Bone Sarcoma is Confirmed

For high-grade sarcomas (osteosarcoma, Ewing sarcoma):

• Refer immediately to a multidisciplinary sarcoma center with expertise in bone tumor management 1
• Initiate neoadjuvant chemotherapy followed by complete en bloc surgical resection including soft tissue components 1
• Postoperative chemotherapy is standard for high-grade lesions 1

For chondrosarcoma:

• Surgery is the primary treatment as chondrosarcomas are resistant to chemotherapy and radiotherapy 1
• Grade I (atypical chondrogenic tumors) in long bones can be managed with curettage with adjuvants (phenol, cement, cryotherapy) 1
• High-grade (II-III) and dedifferentiated chondrosarcomas require wide en bloc resection 1

For unresectable lesions:

• Radiation therapy (60-70 Gy) should be considered for unresectable or incompletely resected disease 1
• Postoperative RT to 55 Gy (64-68 Gy to highest risk area) for R1/R2 resections 1

If Metastatic Disease is Confirmed

• Treat the primary malignancy according to tumor-specific guidelines 1
• Consider palliative radiation therapy for symptomatic bone lesions 1
• Bisphosphonates or denosumab for skeletal-related event prevention 5

Critical Pitfalls to Avoid

• Never perform open biopsy or surgical fixation of pathologic fractures before completing staging workup and referral to a sarcoma center, as improper biopsy technique increases local recurrence risk 1
• Do not assume benign disease in patients <40 years with aggressive painful bone lesions in pelvis/ribs, as primary bone sarcomas have significant malignant potential in this age group 1
• Avoid missing light chain myeloma by relying solely on SPEP—always include serum free light chain assay and 24-hour urine studies 2, 3
• Do not use plain skeletal survey alone—whole-body low-dose CT is superior and changes management in 20% of cases 1
• Remember that osteolytic lesions in primary myelofibrosis affecting pelvis/ribs represent advanced disease with poor prognosis, though this is rare 6