What is the best course of action for a 45-year-old male with a history of gout, who had a bone scan 5 years ago showing possible bony islands with a concern for potential malignancy, and has had no further follow-up?

Management of 5-Year-Old Bone Scan Finding with Possible Bony Islands

Given the 5-year interval without symptoms or progression, and the benign nature of bone islands, no further imaging or workup is needed for the bone scan finding itself—however, you should obtain plain radiographs of the hip now to evaluate the current hip pain, as this is a new symptom requiring assessment. 1, 2

Addressing the Old Bone Scan Finding

Why No Follow-Up is Needed for the Bone Islands

• Bone islands (enostoses) are benign sclerotic lesions that are extremely common incidental findings and have no malignant potential 1
• The 5-year interval without any clinical progression, new symptoms related to those lesions, or need for medical attention effectively rules out any concerning pathology from that original scan 2
• If a malignancy had been present 5 years ago when "malignancy cannot be ruled out" was stated, the patient would have developed progressive symptoms, metastatic disease, or died by now—the natural history of bone malignancies does not allow for 5 years of silent, stable disease 3, 2

The "Cannot Rule Out Malignancy" Caveat

• This phrase on the original report was likely medicolegal language acknowledging that bone scans have limited specificity and cannot definitively characterize lesions 1
• Bone scans show areas of increased metabolic activity but cannot distinguish between benign and malignant processes without correlation to radiographs and clinical context 1, 2
• The appropriate follow-up at that time would have been plain radiographs of the areas of concern—but the 5-year asymptomatic interval has now rendered this moot 1, 2

Evaluating the Current Hip Pain

Initial Imaging Approach

• Obtain plain radiographs of the hip in two orthogonal planes (AP pelvis and frog-leg lateral or cross-table lateral) as the mandatory first investigation for any new bone or joint pain 1, 2
• Radiographs provide critical information about bone architecture, joint space, periosteal reaction, cortical integrity, and any aggressive features that would suggest malignancy 1, 2

Gout-Related Considerations

• The patient's history of gout raises the possibility that hip pain could be related to gouty arthritis, though hip involvement is uncommon in gout 1
• Radiographs in chronic gout may show asymmetrical joint space narrowing, subcortical cysts without erosions, or tophaceous deposits, though these findings are not useful for diagnosing acute or early gout 1
• If hip pain is acute, severe, with rapid onset over 6-12 hours and overlying erythema, this would be highly suggestive of crystal arthropathy and may warrant joint aspiration for definitive diagnosis 1

Age-Appropriate Differential Diagnosis

• At age 45 (now 50 years old), the differential diagnosis for hip pain includes osteoarthritis, avascular necrosis (especially if the patient has risk factors), inflammatory arthritis, stress fracture, or referred pain from the lumbar spine 2, 4
• Primary bone malignancies are statistically uncommon at this age, with metastatic disease and multiple myeloma being more likely if a malignant bone lesion were present 2, 4
• However, given the benign 5-year course, malignancy related to the old bone scan findings is not a realistic consideration 3, 2

When to Pursue Advanced Imaging

Indications for MRI

• If radiographs show an aggressive-appearing lesion (ill-defined margins, permeative destruction, periosteal reaction, soft tissue mass), immediate referral to an orthopedic oncologist or bone sarcoma center is required BEFORE any biopsy 2, 4
• If radiographs are normal but hip pain persists and is severe or progressive, MRI of the hip without and with IV contrast would be appropriate to evaluate for avascular necrosis, occult fracture, soft tissue pathology, or marrow abnormalities 1, 2

Red Flags Requiring Urgent Referral

• Persistent non-mechanical pain, especially night pain that wakes the patient from sleep, is highly concerning for malignancy 2
• Constitutional symptoms such as unexplained weight loss, fever, or night sweats warrant systemic workup 3, 2
• Any radiographic features suggesting aggressive bone lesion require referral to a specialized sarcoma center before biopsy 2, 4

Gout Management Considerations

• Ensure the patient's gout is adequately controlled with urate-lowering therapy, as poorly controlled gout can lead to tophaceous deposits that may occasionally mimic tumors on imaging 5, 6, 7
• Assess for metabolic syndrome components (obesity, hypertension, hyperlipidemia, hyperglycemia), as these are common comorbidities in gout patients and should be addressed 1
• Note that gout patients have an increased risk of developing certain cancers, particularly urological malignancies, though this does not change the immediate management of hip pain 8

What NOT to Do

• Do not order repeat bone scan or PET/CT for the old finding—these will not provide useful information and may generate false-positive results 1, 2
• Do not arrange biopsy of any lesion without first obtaining plain radiographs and, if concerning, referring to a specialized bone sarcoma center 2, 4
• Do not assume hip pain is related to the 5-year-old bone scan finding without proper radiographic evaluation of the current symptoms 1, 2