What is the next best step in managing a patient with a palpable groin mass, approximately 1-2cm in size, with ultrasound findings of a 2.3 x 1.6 x 2.7cm mass showing heterogeneity of cortex and a hypervascular fatty hilum, and a suspicious to lymph node (S/L) ratio of 0.6?

Management of Groin Mass with Suspicious Ultrasound Features

The next best step is to perform an ultrasound-guided core needle biopsy of this groin mass to obtain histologic diagnosis before proceeding with any definitive treatment. 1

Rationale for Core Needle Biopsy

The ultrasound findings are concerning for a potentially malignant process:

• Size >2 cm (measuring 2.3 x 1.6 x 2.7 cm) is a red flag requiring tissue diagnosis 2
• Heterogeneity of cortex suggests abnormal lymph node architecture or possible soft tissue neoplasm 2
• S/L ratio of 0.6 indicates the short axis is 60% of the long axis, which is concerning for a rounded, abnormal lymph node morphology (normal lymph nodes are typically more elongated with S/L ratio <0.5)
• The hypervascular fatty hilum is somewhat reassuring but does not exclude malignancy given the other concerning features

Core needle biopsy is superior to fine-needle aspiration for soft tissue masses, providing better sensitivity, specificity, and correct histological grading. 1, 2 Image-guided (ultrasound) biopsy is preferred over palpation-guided biopsy as it allows confirmation of biopsy accuracy and placement of a marker clip. 2

Critical Pre-Biopsy Considerations

Before performing the biopsy, complete the following evaluation:

• Clinical assessment for other sites of adenopathy and potential non-groin etiologies 1
• Age-appropriate imaging: If patient is ≥30 years old, obtain diagnostic mammogram with ultrasound to evaluate for occult breast cancer (breast cancer is the most common cause of malignant axillary/inguinal lymphadenopathy) 1
• Review for systemic signs of lymphoma or other systemic disease 1

Referral Pathway

If your institution is not equipped for definitive treatment of soft tissue sarcomas or complex oncologic cases, expedite referral to a specialist sarcoma multidisciplinary team (MDT) or orthopedic oncology BEFORE performing the biopsy. 1, 2 This is critical because:

• All patients with suspected soft tissue sarcoma should be managed by a specialist Sarcoma MDT 1
• Discrepancy rates between diagnoses made outside specialist centers range from 8-11% for major discordance and 16-35% for minor discordance 1
• Improper biopsy technique or tract placement can compromise subsequent definitive surgical management

Post-Biopsy Management Algorithm

If biopsy confirms malignancy:

• Refer to specialist Sarcoma MDT for management 1
• Obtain cross-sectional imaging (MRI) of the primary site 1
• Obtain CT chest for staging if soft tissue sarcoma is confirmed 1

If biopsy shows reactive/benign lymph node:

• Clinical follow-up with repeat imaging in 6-12 months to assess for growth 2
• Consider excision if symptomatic or if patient anxiety warrants it 2

If biopsy is non-diagnostic or shows atypical features:

• Consider repeat core biopsy or surgical excision for definitive diagnosis 1

Key Pitfalls to Avoid

• Do not observe this mass without tissue diagnosis given the size >2 cm and heterogeneous features 2
• Do not perform excisional biopsy as the initial diagnostic procedure for masses that may be sarcomas, as this can compromise subsequent definitive surgical management 1
• Do not rely on the "palpable 1-2 cm" size when ultrasound measures 2.7 cm in maximum dimension—imaging is more accurate than palpation 2
• Ensure proper biopsy tract placement along the line of potential future surgical resection if sarcoma is suspected 1