Conference Coverage

Nail biopsies made simple


 

AT THE 2017 AAD SUMMER MEETING

CHICAGO– Maral Skelsey, MD, doesn’t get flowers from her patients very often. But, she said, a big bouquet recently landed on her desk after she had performed a nail biopsy on a patient. The note from the patient read, “That wasn’t as bad as I thought it would be!”

The patient’s relief after the procedure highlights the apprehension that both patients and dermatologists can feel when a nail biopsy becomes necessary, said Dr. Skelsey, director of dermatologic surgery at Georgetown University, Washington, D.C.

Speaking at the summer meeting of the American Academy of Dermatology, Dr. Skelsey said that the most important advice she can give about the nail biopsy is, “Do it early and often.”

Dr. Skelsey reminded the audience that the musician Bob Marley died of malignant melanoma; the first sign of his cancer was a longitudinal melanonychia that went unbiopsied. “The biggest mistake we make is not doing it,” she said.

In performing a nail biopsy, said Dr. Skelsey, the goals are, first and foremost, to optimize the pathologic diagnosis. Correct technique can help avoid complications such as bleeding, infection, and nail dystrophy; the right approach can minimize pain and anxiety, she added.

In preparing for a biopsy for melanonychia, “dermoscopy can be very helpful” in assessing the location of the pigment and fine-tuning planning for the biopsy, said Dr. Skelsey. Also, if the streak of melanonychia has reached the distal nail, sending the clipping for pathology can be useful as well.

For dorsal pigmentation, the proximal nail matrix should be biopsied.

“Do not use a punch biopsy on the nail fold to diagnose melanoma – you will get a false negative,” Dr. Skelsey said. It’s not possible to get an accurate diagnosis going through the nail plate to the nail bed, she said.

The preoperative assessment is usually straightforward. Pertinent items in the patient’s history include any medication allergies, current anticoagulation, and any history of prior trauma to the digit to be biopsied. Occasionally, imaging may be helpful, and patients should always be assessed for vascular insufficiency, she noted.

Preoperatively, she asks her patients to remove nail polish and pretreat the area with povidone iodine for 2 days prior to the procedure. Patients need to have a ride home after the procedure, and should be prepared to elevate the affected extremity for 48 hours post procedure. If a toenail is biopsied, they’re advised to come with a postop shoe.

Her patients receive a 5-minute isopropyl alcohol wash of the area to be biopsied just before the procedure, followed by air drying and a 5-minute scrub with 7.5% povidone iodine, which then is wiped off preprocedure.

For hemostasis, a tourniquet can be improvised with a sterile glove finger and a hemostat; there are also dedicated finger cots available that work well for this purpose, she said. In addition to nail nippers and a nail elevator, an English nail splitter can be helpful, said Dr. Skelsey.

For anesthesia, she said she ordinarily uses a 30 gauge needle with buffered lidocaine and epinephrine at room temperature to deliver a wing block. Beginning about 1 cm proximal and lateral to the junction of the proximal and lateral nail fold, the dermatologist can slowly inject about 1.5 cc per side. As the block takes effect, the lateral nail fold will blanch distally in a wing-shaped pattern. This technique, she said, also has the benefit of acting as a volumetric tourniquet.

“To avulse or not to avulse?” asked Dr. Skelsey. “I used to avulse almost everything,” she said, but noted that a complete avulsion is a “pretty traumatic” procedure. Now, unless a full avulsion is required for complete and accurate pathology, she will usually perform a partial nail plate avulsion.

A partial avulsion can reduce pain and morbidity, and can be done by two different methods: the partial proximal avulsion, and the “trap door” avulsion. In a trap door avulsion, she said, the distal matrix is primarily visualized, so this may be a good option for a longitudinal melanonychia arising from the distal matrix. A Freer elevator is used to detach the nail plate from the bed and the matrix, after which the nail plate can be lifted with a hemostat.

In a partial proximal avulsion, the proximal nail fold is reflected, so it’s a better option when the proximal nail matrix needs evaluation, she said.

After the avulsion has been done, “the matrix has been exposed. Now what? Punch or shave?” asked Dr. Skelsey. She noted that she used to perform punch biopsies on “everything,” and that it’s a good option if the pigmented area spans 3 mm or less. One issue, though, is that the specimen can get stuck in the puncher, and extraction can make it difficult to deliver an intact specimen.

Shave biopsies, Dr. Skelsey said, are effective in dealing with nail matrix lesions. They can yield an accurate pathologic diagnosis, and the biopsied digits healed without nail dystrophy in about three quarters of the cases in one study, she said. Potential recurrence of pigmentation is one drawback of the shave technique, she said.

With a shave biopsy, she performs tangential incisions of the proximal and lateral nail folds, and scores and reflects the nail. Then, the band of pigment is shaved tangentially. She cauterizes the area, and sometimes will use a bit of an absorbable gelatin sponge (Gelfoam) as well. Then the proximal nail fold and nail plate are sutured.

Replacing the nail plate results in better cosmesis and is much more comfortable for the patient, she said. An 18-gauge needle can be used to bore a hole through the avulsed nail plate, which may be held in an antiseptic solution soak during the biopsy. The sutures should then be placed from skin to nail plate, so nail fragments aren’t driven into the skin during the suturing process. Finally, specimen margins should be inked, and separate labeled formalin jars are needed for the nail plate, nail bed, and the matrix.

Dr. Skelsey reported that she had no conflicts of interest.

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