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Skin diseases get misdiagnosed in primary care: primary care physicians are performing vastly more skin biopsies than dermatologists are.

NEW YORK -- Many primary care physicians are evaluating skin disorders and often relying on general pathologists to help them make dermatologic diagnoses, which, according to Dr. Clay Cockerell, could be a recipe for disaster.

Nondermatologists referring skin samples to general pathologists for evaluation is like "the blind leading the blind" and often leads to misdiagnosis and poor patient care, Dr. Cockerell said at the American Academy of Dermatology's Academy 2007 meeting.

Dr. Cockerell, a dermatologist at the University of Texas Southwestern Medical Center, Dallas, said that only 35% of all skin biopsies come from dermatologists. On a day-to-day basis, dermatologists may do a lot more biopsies than their primary care counterparts, but in terms of sheer numbers, primary care physicians are doing vastly more. In addition, economic pressures may be pushing more primary care doctors to work up patients with skin diseases that, in the past, they would have referred to dermatologists.

There also is a shortage of dermatopathologists across the country. Dr. Cockerell said that the majority of young people entering the field are general pathologists looking to specialize; they are not coming from the ranks of dermatology, and consequently they lack training in clinical dermatology. "Fewer dermatologists are entering dermatopathology, and fewer dermatopathologists are reading skin biopsy slides," he said, a situation he sees as a growing gap in dermatologic expertise across the board.

The American Board of Dermatology (ABD) and the American Board of Pathology (ABP) have jointly certified 1,909 dermatopathologists (898 from the ABD and 1,011 from the ABP) since both boards first offered the certificate in 1974. Each year there are approximately 60 individuals, from both boards, certified in this subcertification, according to information provided by the ABD.

"In dermatology, clinical correlation is essential, as many diseases give similar histologic reaction patterns. Some histologic diagnoses are incontrovertible, but others are not. The problem is that many general pathologists think that all histologic diagnoses are incontrovertible, and that what's on the slide is all that matters," he said.

One facet of dermatology that makes it different from many other specialties is that histologically, the same disorder can look very different, depending on the anatomic site involved. The skin on certain body parts, like the elbows, knees and breasts, or any acral skin, can look and behave quite differently from skin of the arms, legs, face, or trunk. Lesions in these sites often do not show the classic textbook histology for the given disease. This is the sort of specialized expertise that primary care physicians and general pathologists often lack.

He described two cases in which lack of dermatologic expertise on both sides of the slide led to an incorrect or delayed diagnosis.

The first case involved a 65-year-old woman who came to a family physician with a solitary skin lesion. The physician, thinking it might be a basal cell carcinoma, took a shave biopsy and submitted it to a general pathology lab. The pathologist noted epidermotropism, exocytosis with atypical lymphoid cells, and a "predominance of T cells," leading to a diagnosis of "probable mycosis fungoides."

The primary care physician informed the patient about this diagnosis, and she immediately hit the Internet to learn more. Not surprisingly, the information she found was extremely upsetting, and--wisely, as it turns out--she sought out a second opinion. Dr. Cockerell and his colleagues looked at the lesion, which was not at all suggestive of mycosis fungoides, and then reassessed the histology. Their conclusion: benign lichenoid keratosis.

The second case involved a 36-year-old woman who had gone to a local primary care doctor for evaluation of a chronic, unresolving rash. The general pathologist who evaluated the histology came to a diagnosis of cutaneous lymphoma, which prompted a referral to an oncologist.

The woman underwent two courses of chemotherapy, which did seem to resolve the rashes immediately post treatment. But they recurred shortly after each treatment, which struck the oncologist as atypical. The oncologist sought further intelligence at a skin tumor conference, and ultimately sent the patient to Dr. Cockerell for evaluation.

What he saw were erupted papules with necrotic areas. The histology showed a lot of atypical lymphoid cells, "but clinically, this did not really look like lymphoma. It turned out to he lymphomatoid papulosis." The patient was promptly treated with PUVA, leading to a complete remission.

"This is what's going on out there in the real world," he said. "Thank God she did not have any side effects from the chemotherapy that she did not need for a lymphoma she did not have."

Clinicopathologic correlation is the key to good dermatologic care, and even within the circle of dermatology, there's a lot of room for improvement.

Careful notation often suffers under the pressures of a busy practice, but it is essential to take your time and to be as explicit and detailed as possible in your clinical descriptions, he said.

"Don't use cryptic allusions to features you're not explaining. Describe lesions as clearly as possible. And don't discount the value of your clinical impression. This can be important information," he said.

He strongly recommended taking more than one biopsy from large lesions, and taking biopsies from several different anatomic sites if a patient has multiple lesions. Ideally, try to get samples from lesions at different stages of development; this can provide a lot of information about the disease process.

Although Dr. Alex Krist, of the Virginia Commonwealth University department of family medicine, admits that the cases presented by Dr. Cockrell are concerning, he sees things differently.

The management of dermatologic conditions is an integral part of primary care training, Dr. Krist said. Family physician residents have to fulfill many requirements to make sure they are proficient in the management of skin conditions. Part of the training is knowing when you can handle dermatologic conditions on your own, and when they need to be referred out.

In a study conducted by Dr. Krist and his colleagues, it was found that family physicians are just as good at managing skin conditions as dermatologists are. The researchers photographed the patients, made a diagnosis and a management plan, and followed the study patients for 4 months. Two dermatologists then reviewed the patient cases (J. Fam. Prac. 2007;56:40-5).

While the study did not focus on skin cancer diagnosis, "I view [primary care physicians] as knowing what they can manage and how to help people find assistance when they need something more. If I have [patients] with melanoma, I will get them in to see a skin specialist. My role is initial diagnosis."

When it comes to physicians sending biopsies to general pathologists, the issue goes beyond physicians not knowing about dermatopathologists, Dr. Cockrell said. Many insurance companies have specific contracted labs to which samples have to be sent. "I send samples to dermatopathologists when a second review is warranted."

Also, added Dr. Krist, "Most of my patients have acute skin conditions that need to be dealt with in a couple days." Referring them to dermatologists could take 4-6 weeks. Even in cities where dermatologists are prevalent, "there are not enough of them to handle all the skin conditions that patients present with," he added.

Some of the mistakes that physicians make when treating patients with skin conditions described by Dr. Cockrell are as follows:

* Clinicians often make mistakes when assessing nail disorders. "We see lots of nail chips submitted for fungal evaluation using PAS [periodic acid-Schiff] staining. But a lot of them are too distal. If you don't chip the nail plate proximally, you can end up with false-negative readings."

When it comes to punch biopsies, don't be shy. "If you make a punch, make it a large one. A 2-mm punch out of a broad lesion is not too helpful for diagnosis. A greater than 5-mm punch is good, or better yet, punch-excise the entire lesion."

Dr. Cockerell said he is a big fan of saucerization excision techniques, especially for melanocytic lesions. It gives the pathologist a generous quantity of tissue from all layers, which tends to increase diagnostic accuracy. "Beware of superficial shave and curettage biopsies. You can really miss things with wafer-thin shaves."

* When taking a biopsy of a blister, make sure to get both the roof and the base of the blister. One or the other alone is insufficient to make an accurate diagnosis. Immunofluorescence staining techniques are important in diagnosing blistering diseases, and biopsy samples obtained from just outside the edge of the blisters are best. Taking a sample from the blister itself can cause degeneration of the immunoreactants, leading to a false-negative impression.

The most important ingredients in good diagnostic work are expertise and clinical judgment, and Dr. Cockerell urged dermatologists to trust their own clinical assessments. "If you are really worried about something, even if the pathologist says it is benign, go ahead and excise it anyway. Yes, you should consult with a dermatopathologist, but at the end of the day, if your clinical judgment and your instinct say, 'Trouble!' just excise the lesion."


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Title Annotation:Dermatology
Author:Goldman, Erik L.
Publication:Internal Medicine News
Geographic Code:1USA
Date:Sep 15, 2007
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