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Dermatopathology: Practical & Conceptual July - September 2007
3. Question: Dermatopathologist, do you really need a microscope?
Mihaela Costache, M.D.
In standard textbooks of dermatopathology, hardly ever is made any comment about studying a section of tissue stained with H & E with the naked eye.[
] It seems that dermatopathologists, in general, perceive sections as being connected invariably to the look through a microscope. Only in the works by Ackerman and collaborators is it mentioned that slides should also be studied before being placed on the table of the microscope.[
] In a recent work on adnexal neoplasms of the skin, he writes that
"Even before placing a slide on the stage of a microscope, a histopathologist should examine it grossly to observe the number of sections of tissue on it."
The results presented in this article show, however, that much more than just the number of sections of tissue can be identified on a slide without using a microscope. Differences in the shape and silhouette can be seen at a glance, and differentiation can be made between cystic, verrucous, and fibromatous lesions. Moreover, the color and structure of material in a cyst atop a verrucous lesion, within a fibromatous nodule, or in a proliferation in the dermis give useful information that may often enable a specific diagnosis without a microscope.
It was also A. Bernard Ackerman who, in the past decades, has emphasized the importance of studying sections of tissue first at scanning magnification. In his book
A Philosophy of Practice of Surgical Pathology,
"The majority of skin diseases can be diagnosed with specificity using the scanning objective, i.e., 1.02.5¥ of a conventional microscope."
] He continues to say that
"nowhere is the cliché about 'missing the forest for the trees' more applicable than in diagnosis of skin diseases by microscopy; the higher the magnification utilized by a microscopist, the more problematic diagnoses often become."
Ackerman's approach for diagnosis by pattern analysis has become the one used most often in the practice of dermatopathology, even though still, in many textbooks of dermatopathology, pictorial material mostly shows photomicrographs of intermediate and high magnifications of a section of tissue.
The method presented here, namely, the examination of sections at the ultimate scanning magnification, without a microscope, cannot be found in any textbook of dermatopathology, even though it is so easy to perform. That procedure, when performed routinely, links dermatopathology perfectly to clinical dermatology because a continuum is created between the clinical impression and the same lesion studied from the perspective of a dermatopathologist. It is an extremely instructive tool for teaching a student the importance of silhouette in the differential diagnosis of skin lesions. Moreover, that method educates a student about proper perception of the size of a lesion. It encourages consideration of how a specific appearance clinically is brought into being by structures seen in a section cut from a biopsy taken from that lesion. Last but not least, it also is highly motivating for a student when a diagnosis made from a slide with the naked eye alone turns out to be correct when the slide is put on the stage of a microscope and then studied for confirmation of the diagnosis at scanning, intermediate, and high magnifications.
At the same time, the method suggested here also teaches, beyond a doubt, the limitations of it whenever a slide placed under the microscope reveals findings not seen in the section on gross examination alone. Simple examples for those limitations are superficially shaved congenital nevi covered by an acanthotic epidermis simulating a seborrheic keratosis, those often being removed together with seborrheic keratosis and placed in one and the same bottle. With the naked eye, such melanocytic lesions will escape correct diagnosis and even when using a 1¥ or 2.5¥ scanning magnification, they may go undiagnosed when no attention is given to the superficial dermis underneath the acanthotic epidermis. As another example, melanoma
arising in a nevus cannot be identified at ultimate scanning magnification; therefore, every melanocytic lesion, no matter how compelling to the diagnosis the impression at scanning magnification may be, should also be studied at intermediate and high-power, with specific attention given to the intraepidermal component of the melanocytic proliferation. Obviously, differentiation between different types of inflammatory diseases of the skin is almost impossible without the microscope. Only rough classification can be accomplished when infiltrates have a considerable density (e.g., nodular dermatitis, diffuse dermatitis, septal panniculitis, and lobular panniculitis) or when they are accompanied by marked changes in the epidermis, e.g., bullous diseases.
In sum, a dermatopathologist can identify a number of lesions without a microscope just by examining a stained section with the naked eye. The method presented here may be used routinely before confirming the diagnosis by way of microscopy and in teaching dermatology and dermatopathology. It demonstrates compellingly the importance of pattern and silhouette for making a diagnosis, and it creates a continuum between clinical dermatology and dermatopathology that may facilitate integration. It shows the limitations of naked eye examination and the indispensability of the microscope for making many more diagnosis with confidence. Armed with the information given in this article, a reader is invited to view, once again,
. How many diagnoses can you make now in this tray of specimens?
Mihaela Costache, M.D., is a dermatologist at County Clinical Hospital in Timisoara., Romania. This article was reviewed by Muna Shuweiter, M.D., and Julia Röglin, M.D. Contact author via e-mail:
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