What is the next step in managing a patient with a focal lytic lesion in the left iliac bone, sclerotic foci in the right iliac bone and proximal bilateral femora, and other incidental findings on imaging?

Management of Focal Lytic Lesion in Left Iliac Bone with Sclerotic Foci

The patient requires urgent referral to a bone sarcoma reference center for multidisciplinary evaluation and biopsy before any definitive treatment decisions are made. 1

Immediate Priority: Referral to Specialized Center

• All patients with suspected primary malignant bone tumors must be referred to a bone sarcoma reference center or specialized bone sarcoma network before biopsy, as bone sarcomas are frequently difficult to recognize as malignant by clinicians, radiologists, and pathologists 1
• The 16 x 9.9 mm lytic lesion with sclerotic margin in the left iliac bone requires tissue diagnosis to exclude malignancy, particularly given it was noted on prior imaging and warrants correlation with clinical history 1

Diagnostic Algorithm

Step 1: Obtain Complete Clinical History

• Document duration, intensity, and timing of any bone pain, particularly night pain 1
• Identify any prior benign/malignant lesions, family history of bone tumors, or previous radiotherapy exposure 1
• Determine patient age, as differential diagnosis varies: after 40 years of age, metastasis or myeloma become more likely than primary bone sarcoma 1
• Assess for any history of trauma (which does not rule out malignancy and must not prevent appropriate diagnostic procedures) 1

Step 2: Physical Examination Specifics

• Examine for size and consistency of any palpable swelling 1
• Assess mobility and relation of any swelling to the involved bone 1
• Evaluate for regional/local lymph nodes 1

Step 3: Advanced Imaging at Reference Center

• MRI of the pelvis with adjacent joints is the best modality for local staging of pelvic tumors and should be performed if not already done 1
• CT may be used to better visualize calcification, periosteal bone formation, cortical destruction, or soft tissue involvement if diagnostic uncertainty remains 1
• The sclerotic foci in the right iliac bone and proximal bilateral femora likely represent bone islands (enostoses) given their sclerotic appearance, but tissue diagnosis of the lytic lesion takes priority 1

Step 4: Biopsy Protocol at Reference Center

• The biopsy must be performed at the reference center by the surgeon who will carry out definitive tumor resection or by a radiologist member of that team 1
• Core needle biopsies under imaging control are appropriate and minimize contamination of normal tissues 1
• Samples must be sent for microbiological culture to exclude infection as a differential diagnosis 1
• The pathology request must include the lesion site, patient age, and radiological differential diagnosis 1
• Samples should be interpreted by an experienced pathologist at the reference center 1

Key Differential Diagnoses for Lytic Lesion with Sclerotic Margin

Malignant Considerations

• Metastatic disease (most common in adults over 40 years) 1
• Multiple myeloma (common after age 40) 1
• Primary bone sarcoma (chondrosarcoma, osteosarcoma, Ewing sarcoma) 1
• Metastasis from occult primary (as demonstrated in case example with breast cancer metastasis to ilium) 1

Benign Considerations

• Bone islands/enostoses (for the sclerotic foci) 1
• Infection/osteomyelitis 1
• Benign bone tumor 1

Critical Pitfalls to Avoid

• Never perform biopsy outside a specialized bone sarcoma center, as improper biopsy technique can contaminate tissues and compromise limb-salvage surgery 1
• Do not assume the lesion is benign based solely on the sclerotic margin; tissue diagnosis is mandatory 1
• Do not delay referral for additional imaging studies if a specialized center has not yet evaluated the patient 1
• The biopsy tract must be considered contaminated and removed with the resection specimen if malignancy is confirmed 1

Management of Incidental Findings

Hernias

• The small midline anterior abdominal wall fat hernia (6.2 mm orifice) and small right inguinal fatty hernia are incidental and do not require urgent intervention unless symptomatic 1

Gastric Mucosal Fold Prominence

• Clinical correlation needed; consider endoscopy if patient has gastrointestinal symptoms 1

Sclerotic Osseous Lesions

• The sclerotic foci in right iliac bone and proximal bilateral femora (largest 6.1 mm) are most consistent with bone islands and typically require no intervention 1
• These were noted on prior imaging, suggesting stability and benign nature 1

Staging if Malignancy Confirmed

• Bone scintigraphy and chest CT to assess for distant disease 1
• Small pulmonary nodules on CT are not specific for malignancy 1
• Additional biopsies from suspicious sites if metastatic disease suspected 1