What is the appropriate management for a patient with a mass on the sternal area?

Management of a Sternal Mass

For any patient presenting with a sternal mass, obtain contrast-enhanced CT chest immediately as the first-line imaging study to definitively characterize the lesion, assess for mediastinal involvement, and guide further management. 1, 2

Initial Diagnostic Approach

Imaging Strategy

• CT chest with contrast is the primary imaging modality, using thin-section imaging (≤5 mm slices) with multiplanar reconstructions to assess relationships to adjacent structures and distinguish the mass from normal anatomic variants 1, 2

• Pre- and post-contrast imaging is essential to distinguish vascular structures from solid masses and identify enhancing components that suggest malignancy 2

• Plain radiographs have limited utility but may identify bone involvement, calcifications, or risk of fracture 1, 3

Critical Differential Considerations

The sternal location requires consideration of several distinct entities:

• Sternal bone lesions: Primary bone tumors (chondrosarcoma, hemangioma), metastatic disease, or infection 3

• Prevascular mediastinal masses: Thymic tumors, lymphoma, germ cell tumors, or thyroid masses that extend to the sternal region 1, 4

• Chest wall soft tissue masses: Sarcomas or benign soft tissue tumors 1

• Normal anatomic variants: The sternalis muscle can mimic pathology on imaging and should be excluded 5

Advanced Imaging for Tissue Characterization

When CT Findings Are Indeterminate

• MRI chest without and with IV contrast provides superior tissue characterization and can distinguish cystic from solid lesions, detect microscopic fat, hemorrhage, and fibrous material 1, 2

• MRI is particularly valuable for neurogenic tumors and can help differentiate thymic hyperplasia from malignancy using chemical-shift imaging 1, 2

• MRI can prevent unnecessary biopsies by definitively characterizing benign cystic lesions 1

Role of FDG-PET/CT

• FDG-PET whole body imaging should be obtained for distinguishing benign from malignant disease, identifying metabolically active areas to guide biopsy, and detecting occult metastatic disease 1, 2

• Higher SUV values suggest high-risk thymoma, thymic carcinoma, or lymphoma rather than low-risk thymoma 1

• A negative FDG-PET/CT is reassuring for excluding malignancy, though false positives can occur with thymic hyperplasia and benign cysts 1

Special Consideration for Breast Cancer Patients

• In patients with known or suspected breast cancer, breast MRI detects sternal metastases more sensitively than bone scan, PET/CT, or chest CT 6

• Sternal metastases on breast MRI are associated with larger primary tumors (mean 6.4 cm), invasive lobular histology, and exhibit rapid initial enhancement with delayed washout curves 6

• Detection of unsuspected sternal metastases alters staging to stage 4 disease in approximately 24% of cases 6

Tissue Diagnosis Strategy

Preferred Biopsy Approach

• Endoscopic/bronchoscopic mediastinal biopsy is the preferred first-line approach if the mass has a mediastinal component, including endobronchial ultrasound (EBUS) and endoscopic transesophageal ultrasound with FNA 2

• Nonradiologic mediastinal mass biopsy may be safer and have higher diagnostic yields than percutaneous approaches 2

Alternative Biopsy Methods

• Image-guided transthoracic needle biopsy can be performed if the mass is safely accessible, with core biopsy more effective than fine-needle aspiration for diagnostic yield 1, 2

• CT-guided biopsy of mediastinal masses has an overall diagnostic yield of 87% for masses with mean size 5.3 cm 1

• Ultrasound-guided biopsy is feasible when the lesion is visible within the sonographic window, with color Doppler providing additional value 1

• DWI MRI may help direct biopsy toward sites of higher cellularity and diagnostic yield 1

Management Based on Imaging Characteristics

If Malignancy Is Evident

• Any mass with obvious signs of malignancy where disease appears isolated should be surgically resected 1

• Laparoscopic/robotic approach is preferred for smaller, contained masses; open approach for larger, invasive tumors 1

• For thymic malignancies, evaluation by a multidisciplinary team (radiation oncologists, surgeons, medical oncologists) is required before treatment 1

If Imaging Suggests Benign Lesion

• Benign-appearing lesions (simple cysts, lipomas with characteristic fat density) may be followed with interval imaging 1

• However, never assume a cystic or indeterminate mass is benign without tissue diagnosis or definitive imaging characterization 2

Critical Pitfalls to Avoid

• Do NOT perform conservative management or follow-up imaging only for symptomatic sternal masses without tissue diagnosis 2

• Do NOT proceed directly to biopsy without MRI evaluation if CT findings are indeterminate 2

• Do NOT assume the sternalis muscle is pathologic—confirm with CT or MRI showing the longitudinal extent of the muscle anterior to the pectoralis major 5

• Do NOT delay referral to a specialist sarcoma center if soft tissue sarcoma is suspected, as inappropriate biopsy can compromise definitive treatment 1

• For retroperitoneal or intra-abdominal masses with sarcoma features, refer to a specialist sarcoma MDT before surgical treatment 1