What are the guidelines for ordering an ultrasound to evaluate a soft tissue mass on the medial bicep?

How to Order an Ultrasound for a Medial Bicep Mass

For a mass on the medial bicep, order plain radiographs first, followed by ultrasound of the upper arm/bicep region if the mass appears superficial to the deep fascia. 1

Initial Imaging Algorithm

Step 1: Plain Radiographs

• Always obtain plain radiographs of the humerus/upper arm first, even though they may seem unnecessary for a soft tissue mass 1, 2
• Radiographs identify calcifications (27% yield), bone involvement (22% yield), and intrinsic fat (11% yield) that can be diagnostic 2
• This step rules out phleboliths, synovial chondromatosis, myositis ossificans, or bone involvement 1

Step 2: Determine Mass Depth on Physical Examination

The key decision point is whether the mass is superficial (above the deep fascia) or deep (below the deep fascia):

If Superficial:

• Ultrasound is highly appropriate as the next imaging study with 94.1% sensitivity and 99.7% specificity 1, 2
• Order as: "Ultrasound of the left/right upper arm to evaluate palpable mass on medial bicep"

If Deep or Uncertain Depth:

• Ultrasound accuracy drops precipitously for deep masses 1
• Consider proceeding directly to MRI without and with IV contrast after radiographs 2

Ultrasound Order Specifications

What to Include in Your Order:

• Anatomic location: "medial bicep" or "medial upper arm"
• Side: left or right
• Clinical indication: "palpable soft tissue mass" with size if known
• Any concerning features: rapid growth, pain, size >5cm 3

Example Order:

"Ultrasound of the right upper arm to evaluate 2cm palpable mass on medial bicep, present for 3 months"

When Ultrasound Findings Require Further Imaging

Proceed to MRI without and with IV contrast if: 1, 2

• Ultrasound shows atypical features (irregular margins, increased vascularity, heterogeneous echotexture)
• Mass is solid rather than cystic with concerning characteristics
• Mass is larger than 5cm 3
• Deep location confirmed on ultrasound 1
• Clinical features remain suspicious despite benign ultrasound appearance 1

Critical Pitfalls to Avoid

• Do not skip radiographs - they are the recommended first imaging study per ACR Appropriateness Criteria, even for obvious soft tissue masses 1
• Do not rely on ultrasound alone for deep masses - accuracy is considerably less for lesions outside subcutaneous tissue 1
• Do not assume all superficial masses are benign - 4% of superficial masses can be malignant, requiring further imaging if features are atypical 1
• Avoid ordering MRI first - literature does not support MRI as the initial examination for soft tissue masses 1

Additional Ultrasound Benefits for This Location

Ultrasound at the medial bicep is particularly useful for: 1

• Differentiating solid from cystic lesions
• Demonstrating relationship to adjacent neurovascular structures (important given proximity to brachial artery and median/ulnar nerves)
• Identifying lipomas with characteristic curved echogenic lines and minimal vascularity 1
• Confirming ganglion cysts if clinically suspected 1