What is the appropriate evaluation and management for a mass in the groin?

Evaluation and Management of a Groin Mass

Initial Diagnostic Approach

Begin with radiographs as the first imaging study for any groin mass to identify calcifications, bone involvement, or intrinsic fat, which can be diagnostic in specific conditions. 1

• Radiographs demonstrate positive findings in 62% of soft tissue masses, including calcification (27%), bone involvement (22%), and intrinsic fat (11%). 2
• However, radiographs have significant limitations for groin masses due to the complex anatomy of this region, where masses may be small, deep-seated, or non-mineralized. 1

Ultrasound Evaluation

For superficial groin masses, ultrasound is the most appropriate next step after radiographs, with sensitivity of 94.1% and specificity of 99.7% for superficial soft tissue masses. 1, 2

• Ultrasound effectively differentiates solid from cystic lesions, confirms fluid content in suspected ganglion cysts, and demonstrates the relationship between a mass and adjacent neurovascular structures. 1
• The most common groin abnormality is an inguinal hernia, which contains bowel loops, omental fat, and peritoneal fluid on ultrasound. 3
• Common benign tumors include lipomas (the most frequent), leiomyomas, dermoid cysts, epidermoid cysts, and lymphangiomas. 3
• Ultrasound should include evaluation of the hip joint, anterior hip musculature, iliopsoas bursa, inguinal lymph nodes, pubic symphyseal region, and inguinal region for hernias using a protocol-driven approach. 4
• Dynamic evaluation during Valsalva maneuver is essential for detecting hernias and must be documented in two orthogonal planes. 4

Critical limitation: Ultrasound diagnostic accuracy drops precipitously for deep masses in large anatomic areas like the groin. 1

Advanced Imaging for Deep or Indeterminate Masses

MRI without and with contrast is indicated when ultrasound findings are inconclusive, the mass is deep-seated, or there are complex anatomical considerations. 2

• MRI provides superior soft tissue characterization and is essential for preoperative planning and local staging. 2
• MRI is particularly useful in the groin region where complex anatomy (flank, paraspinal region, groin, deep soft tissues) limits radiographic assessment. 1

CT can be a useful adjunct after radiography for assessment of mass mineralization in areas where osseous anatomy is complex or obscured. 1

• CT allows distinction of ossification from calcification and identification of characteristic patterns of mineralization. 1
• CT is optimal for detecting the zonal pattern of mineralization essential for diagnosing early myositis ossificans. 1

Vascular Considerations

If a pulsatile groin mass is present, evaluate immediately with duplex ultrasound and/or contrast-enhanced CT to assess for femoral artery aneurysm or pseudoaneurysm. 1

• Femoral artery pseudoaneurysms may result from disruption of a previous femoral suture line, femoral artery access for catheter-based procedures, or injury from puncture. 1
• True femoral artery aneurysms require elective surgical treatment for symptomatic patients with low operative risk and reasonable life expectancy. 1

Tissue Diagnosis

Core needle biopsy under image guidance is the standard approach for suspicious masses requiring histopathological diagnosis, with multiple core samples taken to maximize diagnostic yield. 2, 5

• Excisional biopsy may be more practical for small subcutaneous lesions less than 5 cm or superficial lesions. 2, 5
• Biopsy should be planned carefully so that the biopsy pathway can be safely removed during definitive surgery. 2

Specific Clinical Scenarios

Inguinal Lymphadenopathy

• In vulvar cancer patients, sentinel lymph node biopsy candidates include those with negative clinical groin examination and imaging, primary unifocal tumor <4 cm, and no previous vulvar surgery affecting lymphatic flow. 1
• Complete inguinofemoral lymphadenectomy is recommended if an ipsilateral sentinel lymph node is not detected. 1

Hernia Evaluation

• Ultrasonography is often needed in women for hernia diagnosis, while physical examination is usually sufficient in men. 6
• MRI has higher sensitivity and specificity than ultrasonography for diagnosing occult hernias if clinical suspicion is high despite negative ultrasound findings. 6

Red Flags Requiring Immediate Referral

Any mass with firm consistency, irregular margins, size >5 cm, rapid growth, or deep location requires referral to a specialized sarcoma center with multidisciplinary team evaluation before definitive treatment. 5

• Primary malignant tumors in the inguinal region include sarcomas such as rhabdomyosarcoma and liposarcoma. 3
• Secondary malignant tumors include metastatic lymphomas and metastatic carcinomas from lung, breast, ovary, and gastrointestinal tract. 3

Common Pitfalls to Avoid

• Physical examination alone correctly identifies only about 85% of soft tissue tumors, making imaging mandatory. 2, 5
• Do not assume all groin pain or masses are simple strains—pelvic stress fractures, avulsion injuries, and tumors can be confused with groin strains. 7
• Watchful waiting is not recommended in patients with symptomatic hernias or in non-pregnant women. 6