Guidelines for Skin Cyst Aspiration with Needle
Fine needle aspiration is generally not recommended as the primary treatment for most skin cysts due to high recurrence rates and potential complications, with surgical excision being the preferred definitive treatment for most skin cysts. 1
Classification and Diagnosis of Skin Cysts
- Skin cysts are classified based on their characteristics, with proper identification being crucial for determining appropriate management 1
- Simple cysts are anechoic (cystic), well-circumscribed, round or oval with well-defined imperceptible wall and posterior enhancement 1
- Complicated cysts have most but not all elements of a simple cyst and do not contain solid elements, intracystic masses, thick walls, or thick septa 1
- Complex cysts have some discrete solid component, which may include thick walls, thick septa, and/or intracystic mass 1
Indications for Aspiration
- Therapeutic fluid aspiration can be considered for simple cysts if clinical symptoms persist 1
- Aspiration may be more strongly considered in patients likely to be lost to follow-up 1
- For complicated cysts, options include either aspiration or short-term follow-up with physical examination and imaging every 6-12 months 1
- Aspiration is contraindicated for solid or mixed ovarian masses due to risk of spreading cancer cells 1
Aspiration Technique
- Select appropriate needle size based on the cyst characteristics - smaller gauge needles (22-gauge) are suitable for small lesions (4-5 mm) 2
- Apply proper skin disinfection according to protocol before needle insertion 1
- Insert the needle at an appropriate angle (typically 25°) 1
- When blood flashback is visible, aspirate back 1-5 mL with a syringe 1
- Flush the needle with normal saline solution and clamp 1
- The syringe must aspirate and flush with ease - monitor for signs of infiltration such as pain, swelling, or discoloration 1
Post-Aspiration Management
- Cytologic examination is recommended if bloody fluid is obtained from the cyst 1
- For cysts that resolve following aspiration but contain bloody fluid, placement of a tissue marker followed by cytologic evaluation is recommended 1
- In the event of a persistent mass after aspiration, a biopsy is needed 1
- For complicated cysts that increase in size after aspiration, biopsy is recommended 1
Special Considerations for Different Cyst Types
- Epidermal cysts: FNAC has shown 100% sensitivity and correlation with histopathology 3
- Ganglion cysts: FNA can be an effective, nontraumatic method of treatment with good outcomes 4
- Steatocystoma multiplex: FNA may provide a useful alternative to surgical methods as it is inexpensive, well-tolerated, and has no associated morbidity 2
- Adnexal/sebaceous cysts: FNAC has demonstrated good diagnostic accuracy 5
Limitations and Contraindications
- Ultrasonographically guided needle aspiration has been shown to be insufficient therapy for skin abscesses with only 26% success rate compared to 80% for incision and drainage 6
- The presence of MRSA decreases the success of needle aspiration (8% success rate) 6
- Fine-needle aspiration for cytological examination of ovarian masses is contraindicated due to risk of spreading cancer cells 1
- Aspiration alone may not give a confirmative diagnosis for certain skin lesions, particularly adnexal tumors 3
Follow-up Recommendations
- For simple cysts that have been aspirated, routine screening is recommended 1
- For complicated cysts that have been aspirated, physical examination with or without ultrasound every 6-12 months for 1-2 years is recommended to assess stability 1
- If a cyst recurs after aspiration, surgical excision should be considered 1
- For cysts with bloody aspirate that resolve, follow-up with physical examination with or without imaging every 6-12 months for 1-2 years is recommended 1