In a 57-year-old man with a hard, immobile, painless forehead mass that has been enlarging and who was struck in the same area by a baseball bat approximately 30 years ago, what is the best imaging study to evaluate this lesion?

Best Imaging for Hard, Immobile, Painless Forehead Mass with Remote Trauma History

Plain radiographs (X-rays) of the skull/forehead are the best initial imaging study for this patient 1.

Rationale for Radiography First

According to ACR Appropriateness Criteria for primary bone tumors, radiographic evaluation of the area of interest is generally considered the initial study of choice when evaluating suspected bone lesions 1. This applies directly to your patient's hard, immobile forehead mass.

Why Radiographs Are Optimal Initially

Plain films provide critical diagnostic information including:

• Tumor margin characteristics (sharp vs. infiltrative) - the most reliable indicator of biological potential 1
• Periosteal reaction patterns - helps distinguish benign from aggressive lesions 1
• Matrix mineralization - key to identifying the underlying histology 1
• Baseline documentation for future comparison if observation is chosen 1

The ACR guidelines note that radiographs correctly categorize bone tumors as benign versus malignant in approximately 82.5% of cases based on these features alone 1.

Clinical Context: Post-Traumatic Bone Lesions

The 30-year history of trauma to this exact location is highly relevant. Several case reports document post-traumatic bone lesions in the frontal region:

• Post-traumatic osteomas are well-documented benign lesions that develop after frontal bone trauma and present as slow-growing, hard masses 2, 3
• Intraosseous hemangiomas can enlarge after head trauma, presenting as forehead masses that grow over time 4
• Intradiploic epidermoid cysts may expand following trauma with chronic hemorrhage 5

All of these entities have characteristic radiographic appearances that can guide further management.

When to Proceed to Advanced Imaging

CT scanning (without and with IV contrast) should be obtained if:

• Radiographs show aggressive features (cortical destruction, periosteal reaction)
• The lesion appears indeterminate on plain films
• Surgical planning is needed 1

CT is particularly valuable for assessing matrix mineralization and cortical involvement that may not be fully evident on radiographs 1.

MRI (without and with IV contrast) is indicated for:

• Evaluating soft tissue extension
• Preoperative planning once the diagnosis is established
• Assessing relationship to vascular structures 1

However, MRI should typically follow radiographic imaging, which helps plan the MRI protocol 1.

Common Pitfalls to Avoid

• Do not skip radiographs and proceed directly to CT/MRI - this wastes resources and may miss characteristic plain film findings that establish the diagnosis
• Do not assume all post-traumatic masses are benign - while osteomas are most likely given the history, malignancy must be excluded through proper imaging evaluation
• Ensure adequate radiographic views - multiple projections (AP, lateral, tangential) are needed to fully characterize skull lesions

Practical Algorithm

1. Order plain skull radiographs (multiple views including tangential view of the mass)
2. If radiographs show benign features (well-defined margins, no periosteal reaction, typical osteoma appearance) → Consider observation or surgical referral based on cosmetic concerns
3. If radiographs show aggressive or indeterminate features → Proceed to CT with and without contrast for detailed characterization 1
4. If surgical intervention planned → Add MRI for soft tissue evaluation and operative planning 1