What is the next step in managing a superficial abdominal mass identified on a computed tomography (CT) scan that warrants a biopsy?

Management of Superficial Abdominal Mass on CT Scan

For a superficial abdominal mass identified on CT scan, proceed directly with image-guided core needle biopsy using CT guidance with 14-16 gauge needles, obtaining 4-6 cores from different angles through a single skin entrance to establish histologic diagnosis before definitive surgical planning. 1

Diagnostic Approach

Initial Imaging Confirmation

• Contrast-enhanced CT is the preferred imaging modality to fully characterize the superficial abdominal mass, assess its relationship to surrounding structures, and determine if it represents an intramural versus extramural lesion 1
• For superficial lesions >5 cm and deep lesions of any size, imaging must be completed before any surgical intervention 1
• MRI may provide additional information if CT findings are indeterminate, particularly for distinguishing cystic from solid components and assessing tissue characteristics 2

Biopsy Technique

Core needle biopsy is the standard approach for soft tissue masses >3 cm, as it provides superior diagnostic yield compared to fine-needle aspiration 1:

• Use 14-16 gauge automated cutting needles with coaxial introducer for a single skin entrance 1
• Obtain 4-6 cores while varying the angle into the tumor to ensure adequate sampling 1
• Image guidance (CT or ultrasound) should be used to avoid necrotic areas and target viable tumor tissue 1
• The diagnostic yield for cutting-needle biopsy ranges from 82-100% for specific diagnosis, significantly superior to fine-needle aspiration (54-67%) 3

Critical Technical Considerations

Avoid necrotic or hemorrhagic areas during biopsy planning by using imaging guidance to target the most cellular portions of the mass 1, 2:

• Sample adequacy rates are 93-100% with cutting-needle technique versus 70-92% with fine-needle aspiration 3
• For masses poorly visualized on standard CT, consider using contrast enhancement or anatomic landmarks to improve targeting accuracy (96-98% accuracy) 1
• The risk of peritoneal contamination is negligible when proper technique is employed 1

Multidisciplinary Discussion

All diagnostic procedures should be discussed within a multidisciplinary tumor board (MDTB) before proceeding, particularly for suspected sarcomas or complex masses 1:

• MDTB should include medical oncology, radiology, surgery, and pathology at minimum 1
• This approach improves clinical outcomes and cost-effectiveness for sarcoma management 1

Pathologic Processing

Tissue samples must be fixed in formalin (never Bouin fixation) to preserve the ability to perform molecular analysis 1:

• Central pathological review by an expert sarcoma pathologist is strongly recommended 1
• Molecular pathology testing should be performed when morphology and immunohistochemistry are insufficient for precise diagnosis 1
• Frozen tissue collection is encouraged for potential future molecular assessments 1

Complications and Safety

The complication rate for CT-guided abdominal biopsy is low (approximately 6%), with self-limited bleeding being the most common adverse event (occurring in 85.7% of complications) 4:

• Major bleeding occurs in <1% of abdominal/retroperitoneal biopsies 3
• Complications are not significantly associated with lesion location, patient age, comorbidities, or proximity to large vessels 4
• For hypervascular lesions, the risk of post-biopsy bleeding may be as high as 9-12% 1

When to Avoid Biopsy

Proceed directly to surgical excision without biopsy in the following scenarios 1:

• Small superficial masses amenable to simple laparoscopic excision where surgery is both diagnostic and therapeutic
• Cystic masses at high risk for peritoneal contamination (should only be biopsied in specialized centers) 1
• Emergency presentations where immediate surgical intervention is required 1

Common Pitfalls to Avoid

• Do not perform endoscopic or superficial biopsies for submucosal or deep masses, as they rarely provide representative material 1
• Do not rely on fine-needle aspiration alone when specific histologic diagnosis is required for treatment planning 3
• Do not skip contrast administration unless absolute contraindications exist, as it significantly improves lesion characterization 2
• Do not proceed with definitive surgery before obtaining tissue diagnosis for larger masses requiring multivisceral resection, as this allows proper surgical planning and may avoid unnecessary surgery for non-surgical diseases (lymphoma, fibromatosis) 1