Key Characteristics for Describing Finger Cysts
When describing a finger cyst, it is essential to characterize it by its ultrasound features, location, size, and content to determine appropriate management and malignancy risk.
Classification of Cysts by Ultrasound Features
Finger cysts should be classified into three main categories based on their ultrasound characteristics 1, 2:
Simple Cyst
- Anechoic (cystic)
- Well-circumscribed
- Round or oval shape
- Imperceptible wall
- Posterior enhancement
- Considered benign
Complicated Cyst
- Contains low-level echoes or intracystic debris
- No solid components
- No thick walls or septa
- Round, circumscribed mass
- Low risk of malignancy (<2%)
Complex Cyst
- Has discrete solid components
- May have thick walls, thick septa
- May contain intracystic masses
- Both anechoic (cystic) and echogenic (solid) components
- Higher risk of malignancy (14-23%)
Location Characteristics
The location of finger cysts should be described with precision 3:
- Anatomical finger involved (most commonly the third finger)
- Level of involvement:
- Metacarpophalangeal joint (63% of cases)
- Proximal phalanx (31% of cases)
- Distal phalanx/pulp
- Relationship to adjacent structures:
- Flexor tendon sheath association
- Joint proximity
- Connection to joint space (if present)
Size and Morphology
Document the following size and morphological features 3:
- Dimensions in millimeters (average size ~6mm)
- Volume (average ~90mm³)
- Presence/absence of pedicle
- Single vs. multilocular
- Presence of septa (found in approximately 34% of cases)
- Wall thickness
Content and Special Features
Describe the content and any special features 4, 3:
- Homogeneous (69%) vs. heterogeneous appearance
- Anechoic (66%) vs. mixed echogenicity
- Presence of internal debris
- Any calcification or ossification (extremely rare) 5
- Fluid characteristics if aspirated (clear vs. bloody)
Associated Findings
Note any associated findings that may indicate origin or complications 6, 4:
- Connection to joint space
- Tendon sheath involvement
- Signs of infection
- Associated joint effusion
- Evidence of osteoarthritis in nearby joints
Clinical Correlation
Include relevant clinical information 2, 7:
- Differentiate between ganglion cysts and cutaneous myxomas
- Presence of pain or tenderness
- Functional limitations
- History of recurrence after previous treatment
- Signs of infection (if present)
Management Implications
The description should guide management decisions 1, 2:
- Simple cysts: Routine screening or aspiration if symptomatic
- Complicated cysts: Aspiration or follow-up with ultrasound every 6-12 months
- Complex cysts: Tissue biopsy due to higher malignancy risk
- Infected cysts: Incision and drainage with culture
By systematically describing finger cysts using these characteristics, clinicians can accurately classify the lesion, determine its risk profile, and select the appropriate management approach.