EXPERT ANALYSIS FROM THE 2017 AAD SUMMER MEETING
NEW YORK (FRONTLINE MEDICAL NEWS) – If dermatopathologists had a wish list they could give their dermatologist colleagues, what might it include? High up on the list for many, said Robert Phelps, MD, might be to have them share the clinical picture, treat the specimen gently, and give the best landmarks possible.
Speaking at the summer meeting of the American Academy of Dermatology, Dr. Phelps, director of the dermatopathology service at Mount Sinai Medical Center in New York, led off the dermatopathologist-run session – appropriately titled “Help Me Help You” – by asking, “How can the clinician provide the optimal biopsy?”
It’s always helpful to have as much clinical information as possible, said Dr. Phelps, whose discussion focused on tips for neoplastic lesions. This might include prior history of malignancy, autoimmune disease, pathergy, or other relevant medical history, but clinical pictures can also be a big help, although there can be technical and patient privacy issues to overcome, he noted. If, for example, a larger lesion or rash is being biopsied rather than excised, it can be very helpful to see the larger field and full area of distribution of the lesion in question. Submitting multiple specimens for rashes and larger lesions is always a good idea too, he added.
Although curettage can be a great way to biopsy – and perhaps even definitively treat some lesions – problems can arise on the dermatopathologist’s side when melanocytic lesions are curetted for biopsy, according to Dr. Phelps , a practicing dermatologist and a dermatopathologist. “By virtue of the force of the biopsy, the specimen is often fragmented, and histology can be distorted,” he said. One element of that distortion can be that melanocytes can appear to be free floating, which is a problem. “Dyshesion of melanocytes is usually an indication of atypia … It is an important histologic clue as to the possibility of a malignancy supervening.”
These factors can make it tough for a dermatopathologist to make an accurate call. “If there are free-floating melanocytes from a curetted specimen, I can’t rule out invasive melanoma,” explained Dr. Phelps, since he can’t tell if he is seeing true atypia or disruption that’s an artifact of the collection technique.
In this instance, he said, a dermatopathologist would be “obligated to overcall, because one couldn’t really determine the pathology.” The bottom line? “Don’t curette biopsies of melanocytic lesions.”
Another technique that can interfere with the ability to read a tissue specimen accurately is electrodessication. Although it’s often performed in conjunction with curettage, electrodessication can cause changes in tissue consistent with thermal injury. “Essentially, the tissue has been burned,” Dr. Phelps pointed out. This can result in a characteristic streaming pattern of nuclei, and the dermis can acquire a “peculiar homogenized appearance,” he said.
Although electrodessication can be a useful technique to make sure margins are controlled, “when you do this, just be aware that the interpretation is difficult,” he noted. “It’s difficult to tell where the margins are and if they are the appropriate and correct margins,” he said.
When possible, try to avoid squeezing the tumor, Dr. Phelps advised. Excessive pressure on the specimen can distort cell architecture and make pathological diagnosis really challenging, particularly in lymphoid tumors, he said.
“Often, the tumor is not recognizable,” he added. Crush artifact can result in an appearance of small bluish clumps and smearing of collagen fibers. The effect, he said, can be particularly pronounced with small cell carcinoma and lymphoma, and with rapidly proliferating tumors.
Dr. Phelps said that during his training, he was taught not to use forceps to extract a stubborn punch biopsy specimen; rather, he was trained to use a needle to tease out the specimen. Fear of a self-inflicted needle stick with this technique may be a deterrent, he acknowledged. If forceps are used, he suggested being as gentle as possible and using the finest forceps available.
When pathologists receive an intact excised lesion – one not obtained using a Mohs technique, “delineation of the margin is essential,” Dr. Phelps said. Further, accurate mapping is critical to helping the examiner understand the anatomic orientation of the specimen, a key prerequisite that enables accurate communication from the dermatopathologist back to the clinician if there’s a question regarding the need for retreatment, he added.
For an elliptical excision, ideally, both poles of the ellipse would be suture-tagged, and at least one tag is essential, he said. Then superior and inferior borders can be inked with contrasting colors, and the epidermal borders of the lesion should be marked as well. When the specimen is submitted, it should be accompanied by an accurate map that clearly indicates the coding for medial, lateral, inferior, and superior aspects of the specimen. “Always prepare a specimen diagram for oriented specimens,” Dr. Phelps noted.
Don’t forget to make sure that the left-right orientation on the diagram corresponds to the specimen’s orientation on the patient, he added. Some facilities use a clock face system to indicate orientation and positioning, which may be the clearest method of all.
Sometimes, it’s difficult for the dermatopathologist to visualize whether the specimen is aligned in true medial-lateral fashion, or along skin tension lines, which tend to run diagonally, so “the more clinical information, the better,” he said. “With good mapping, precise retreatment can be optimal,” he said.
Dr. Phelps reported that he had no relevant conflicts of interest.
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