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Nail biopsies are key to ruling out some types of neoplasm or skin cancer. Certain types of warts are associated with skn cancer and can be distinguished through nail biopsy. Dermatologists who shy away from nail biopsies because they don't know how to do it properly and are worried they will cause permanent scarring, should consider mentoring with a dermatologist who does nail biopsies in order to gain a higher level of comfort for performing the procedure.
"The two cancers we see the most often with nail biopsies are melanoma and squamous cell carcinoma. As dermatopathology has evolved as a specialty, it really helped us not only with the skin and scalp, but with also the nails, in making more concrete diagnoses," Dr. Daniel says.
Certain types of warts are associated with squamous cell skin cancer.
Oftentimes, dermatologists shy away from doing the nail biopsy procedure.
"Although there are some dermatologists who will perform a nail biopsy, many others have some trepidation in doing it because they don't know how to do it properly, and they are worried that they will cause permanent scarring," Dr. Daniel tells Dermatology Times.
The point on the nail unit - either the nail plate, the nail bed or the nail root or matrix - where the biopsy is performed depends on where the cause of the abnormality is.
"It is important to keep in mind where the causative lesion is. For example, the distal part of the nail root makes the deeper part of nail plate and the more proximal part of the matrix (or the part that is really underneath the cuticle) makes up the more superficial portion. Sometimes, if it is something appearing in the nail plate and you need to biopsy the matrix, then it is important to keep in mind where the causative lesion is," Dr. Daniel says.
The nail bed is a place in which you can find psoriasis lichen planus and other disorders. The cause for them may be in the nail root or elsewhere. Depending on the manifestation that can be seen is where the dermatologist would do the biopsy, Dr. Daniel says.
A longitudinal pigmented band - a black or brown band that goes up or down - is sometimes suggestive of melanoma in the nail unit.
"If clinicians see the band and are not sure if it has a benign cause or not, it is important to do a biopsy," Dr. Daniel explains.
"Dermatologists can look for a little clue there called the Hutchinson's sign. If there is color or pigment leaching onto the nail folds from the nail unit itself that can often suggests a melanoma," he says. Melanoma is also more suspect if the lines are multicolored or wider.
Dr. Daniel notes that as with other biopsies anywhere else on the body, it is important to have adequate local anesthesia to deaden the point of biopsy. There are two methods of biopsying nails: a digital block or the distal approach. For the digital block, the Xylocaine (lidocaine, Abraxis) is injected just distal to where the digit meets the hand. In the distal approach, the area all the way around the nail plate is deadened.
"Then, I prefer to send the sample to a dermatopathologist ... and then have it analyzed," Dr. Daniel says.
Refer or not?
A dermatologist who does not do nail biopsies usually will refer to another dermatologist or a hand surgeon if there is cause for concern or they think it is something significant, like a process that can scar the nail or for some type of skin cancer.
Dr. Daniel points out dermatologists can consider mentoring with another dermatologist who does nail biopsies to gain confidence about performing the procedure. In addition, they can attend a nail surgery seminar or review a textbook.
Finally, some patients present with a nail disorder that does not appear to be cancerous. In these cases, dermatologists may not pursue a nail biopsy at first.
However, Dr. Daniel notes, if the nail problem does not get better or if it is a noncancerous inflammatory disorder that is bothersome or causing considerable nail damage, it would behoove the dermatologist to perform a biopsy or get someone else to do it.