What is the updated protocol for performing a nail biopsy on a patient, considering factors such as minimizing pain and preventing infection?

Updated Protocol for Nail Biopsy Technique

When performing a nail biopsy, the nail plate must be sufficiently removed to expose the underlying lesion, and the nail matrix must be sampled by a practitioner skilled in nail apparatus biopsy, with the choice between excisional or incisional biopsy determined by lesion size. 1

Pre-Procedure Preparation

Infection Control Measures

• Perform hand hygiene with antimicrobial soap and water or alcohol-based hand rub before donning gloves 2
• Wear medical gloves when potential exists for contacting blood or body fluids 2
• Use a new pair of medical gloves for each patient and wash hands immediately after glove removal 2
• Wear surgical mask and eye protection with solid side shields during procedures likely to generate splashing of blood or body fluids 2
• Don protective clothing (gown, laboratory coat, or uniform) that covers personal clothing and skin likely to be soiled 2

Patient Selection and Counseling

• Ensure the patient has no peripheral vascular compromise before proceeding 3
• Explain to the patient the risks associated with the procedure, expected functional handicap, time required for nail regrowth (typically months), possibility of permanent nail dystrophy, and possibility of not achieving a diagnosis even after biopsy 3

Anesthesia Protocol

• Administer local anesthesia using periprostatic injection technique or topical anesthetic, as these methods have been shown to be safe and efficacious in reducing discomfort during biopsy procedures 2
• For exceptional cases such as patients with contraindications to local anesthesia, consider intravenous sedation or general anesthetic 2

Biopsy Technique Selection

For Suspected Subungual Melanoma or Melanonychia

• Remove the nail plate sufficiently to expose the underlying lesion 1, 2
• Sample the nail matrix adequately, as melanoma arises in this location 2, 1
• Perform excisional biopsy when feasible, encompassing the entire lesion 1
• Use incisional biopsy for larger lesions, ensuring adequate sampling of the nail matrix 1
• Only practitioners skilled in biopsy of the nail apparatus should perform these procedures 2

For Other Nail Pathology

• Nail plate biopsy: Easiest technique with least scarring, appropriate for nail plate disorders 3
• Nail bed biopsy: Use elliptical excision or punch technique for nail bed pathology 3
• Nail matrix biopsy: Options include elliptical excision, punch excision (≤3 mm), or tangential/shave excision 3
• Nail fold biopsy: For perionychial pathology 3

Punch Biopsy Specifications

• Punch biopsies of ≤3 mm can be used for nail matrix sampling to minimize risk of permanent nail dystrophy 3
• Punch biopsy can be performed in all regions of the nail apparatus in the presence or absence of nail plate 4
• Handle the anatomic site and specimen carefully to achieve successful diagnosis 4

Hemostasis Management

• Prefer topical hemostatic agents such as aluminum chloride or ferric subsulfate solution over electrocautery 2
• Add topical coagulants (absorbable gelatin) as needed 2
• Use spot electrocautery only when necessary to control postprocedural bleeding 2

Post-Procedure Specimen Handling

Clinical Information to Provide Pathologist

• Document the site, size, presence of ulceration, bleeding, or nodular features 1
• Photograph the lesion before biopsy 1
• Note macroscopic satellites around the clinical lesion, as these upstage melanoma to stage III 2

Required Pathology Reporting Elements

• Breslow thickness measurement 1
• Presence or absence of ulceration 1
• Margins of excision status 1
• Clark level 1

Minimizing Complications

Pain Management

• Use appropriate anesthesia techniques as outlined above to minimize discomfort 2
• Minor anesthetic techniques greatly enhance acceptability, particularly with extended biopsy techniques 2

Preventing Permanent Nail Dystrophy

• Exercise great care in nail matrix biopsy to minimize risk of permanent nail dystrophy 5
• Use punch biopsies ≤3 mm when sampling the nail matrix 3
• Ensure proper selection of biopsy technique based on the specific nail pathology 6

Infection Prevention

• Remove gloves that are torn, cut, or punctured as soon as feasible and wash hands before regloving 2
• Keep fingernails short with smooth, filed edges to allow thorough cleaning and prevent glove tears 2
• Change protective clothing immediately if penetrated by blood or other potentially infectious fluids 2

Expected Outcomes and Limitations

• Histopathologic changes are diagnostic in approximately 63% of cases overall 6
• Diagnostic yield is higher in infectious disorders of the nail unit 6
• Scarring and nail dystrophy occur in approximately 29.2% of patients 6
• Nail biopsy is particularly useful in cases with isolated nail involvement, absence of skin lesions, and disorders such as twenty-nail dystrophy 6

Critical Pitfalls to Avoid

• Never perform superficial sampling that may underestimate Breslow thickness in suspected melanoma 2
• Do not proceed without adequate nail plate removal when the underlying lesion needs to be visualized 1, 2
• Avoid nail matrix biopsy by inexperienced practitioners, as this carries the highest risk of permanent nail dystrophy 5, 2
• Do not use artificial fingernails or extenders when performing procedures with direct patient contact 2