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- Presentation
Tangential Excision and Matrix Shave Biopsy Techniques for Nail Lesions
Description
The speaker advocates tangential excision, also called matrix shave biopsy, as the preferred way to biopsy many nail lesions because it removes the whole lesion rather than sampling only a small part. The technique is emphasized especially for longitudinal melanonychia, since most nail melanomas present this way and early biopsy is crucial to avoid delayed diagnosis and upstaging. It is also useful for erythronychia, onychopapilloma, onychomatricoma, and certain inflammatory nail disorders. The goals are high diagnostic yield, accurate staging, recurrence prevention, minimal scarring, and low morbidity. If a patient refuses matrix biopsy, nail clippings may sometimes show melanocyte remnants that support concern for melanoma, but tissue biopsy remains necessary. The speaker contrasts punch biopsy with tangential excision, noting that punches can be inadequate when lesions are narrow but long. Practical points include reflecting the proximal nail fold, elevating the nail plate, excising the lesion tangentially with narrow margins, placing specimens on a nail map, and sending photos or dermoscopy to pathology. For erythronychia, the speaker describes trapdoor avulsion to preserve nail bed epithelium, while onychomatricoma may require partial nail avulsion and can sometimes be recognized by holes in the clipped nail plate. Overall, the talk presents tangential excision as the mainstay and preferred biopsy method for most nail matrix and related lesions.
View moreConclusions
- Tangential or shave excision of the nail matrix is presented as the preferred biopsy technique for most cases of longitudinal melanonychia because it samples the entire lesion, improves diagnostic yield, and usually causes minimal scarring.
- The approach is especially valuable because nail melanoma is often diagnosed late, and taking an excisional specimen with adequate margins helps provide staging information and reduce the risk of missed or understaged cancer.
- For small distal matrix lesions under 3 mm, a punch biopsy can still be appropriate, but wider distal lesions and most proximal matrix lesions are better sampled with a matrix shave.
- The lecture argues that tangential excision can also be effective for longitudinal erythronychia, provided the specimen includes the relevant nail bed and hyponychium so epithelial lesions like onychopapilloma or Bowen disease can be identified.
- Onychomatricoma can often be recognized clinically or by nail clipping, and tangential excision or limited avulsion is usually sufficient for diagnosis and treatment.
- Published series and reviews are cited to support that matrix shave biopsies are diagnostic in essentially all cases studied and that most patients heal with little or no scarring.
- A small amount of residual pigment or recurrence after tangential excision is common and is presented as compatible with good healing rather than treatment failure.
- Overall, the presentation concludes that matrix shave or tangential excision is the mainstay for sampling nail matrix tumors, while the depth and extent of biopsy should be adjusted to the suspected tumor type.
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