By Gregory A. Hosler, M.D., Ph.D.
At ProPath we use standard reporting systems for melanocytic lesions and margin assessment. The following terminologies are used when reporting. Please call me or any of the dermatopathologists on our team if you have questions about our terminology, our philosophy, or if you wish to discuss a particular patient.
Nevus with Architectural Disorder (“Dysplastic” Nevus)
We use the recommended NIH nomenclature of “nevus with architectural disorder” to diagnose melanocytic lesions also known as “dysplastic nevi” and “Clark nevi”. We use a binary system for grading the atypia – “mild” or “severe” (we do not use “moderate”). We choose to omit “moderate” because, in our experiences with consultation material, this diagnosis is not very reproducible, it is over-used, and it causes confusion for clinicians regarding management of the lesion. Based on a review of our internal and consultation cases, and review of the literature, we estimate that by using a binary system, most (~75%) cases of lesions with “moderate” atypia would fall into our “mild” category. Because many clinicians feel obligated to re-excise nevi with “moderate” atypia, our binary system leads to a reduction in re-excision rates and overall health care costs. This binary system is also practical and actionable. In cases with severe atypia when the lesion has not been completely excised, a comment on the report will recommend conservative excision. No specific recommendation is offered for nevi with “mild” atypia but monitoring with follow-up visits is considered an acceptable approach. All reports of nevi with architectural disorder will include a comment indicating that these lesions may be part of the Familial Mole Melanoma Syndrome.
Top: Mild (200x); Bottom: Severe (200x)
Atypical Melanocytic Hyperplasia
Lesions that have intra-epidermal spread that falls short of melanoma in situ are classified as “atypical melanocytic hyperplasia” (AMH). The atypia is not graded, as it is the pattern that is of concern. These lesions are best considered a precursor to melanoma in situ, and therefore, removal of these lesions likely prevents progression to melanoma. The report will include a comment that AMH may represent an evolutionary precursor to melanoma and recommend that the lesion be conservatively excised, especially if it is part of a larger lesion or the area re-pigments.
Atypical Compound Nevus
Lesions that have atypia in both the junctional and dermal components, but not diagnostic of melanoma, are classified as “atypical compound nevus” (ACN). Because the histologic differential diagnosis includes invasive melanoma, which can have a significant impact on patient management, we often perform ancillary studies on these lesions. These studies include immunohistochemistry, fluorescence in situ hybridization (FISH), and/or possibly gene expression profiling (GEP). For lesions designated as ACN, we recommend conservative excision, especially if part of a larger lesion or if the area re-pigments. Please note that we do not use CAN, AMH, and nevus with architectural disorder (“dysplastic” nevus) synonymously. The latter is a category of lesions with a distinct histologic pattern and an association with the Familial Mole Melanoma Syndrome while AMH is best considered a precursor to melanoma in situ.
Margin Assessment on Biopsy Material
Margin examination may be requested; however, only the Mohs technique allows examination of 100% of the margin. Margin assessment on biopsies is problematic as only two of three dimensions are able to be visualized (only a profile of the biopsy is visualized on a slide), potentially leading to a false-negative result, and tissue shrinkage during routine processing may lead to a false positive result as the lesion is squeezed (via artifact) to the margin. When we report margins, we state that “the examined margins are negative” or that the lesion extends to the deep or a lateral margin, recognizing that there are limitations as outlined above. For example, for a shave biopsy (or excision/saucerization), we may say “the examined margins are negative”. This means that on the two dimensions which can be examined on a slide, the margins are negative. This does not necessarily mean that the lesion has been fully removed.
We recognize that margin assessment, despite its limitations, may have value regarding patient management with certain practices and with certain patients. If you mark on the requisition that the specimen is a biopsy, no margin assessment will be made unless requested. If you mark that the specimen is some type of excision, we will assess the margins as best as possible. If there are any standing requests for margins on certain types of diagnoses, please let us know and we will accommodate the request.
Hosler GA and Patterson JW. Chapter 32: Lentigines, nevi, and melanomas. In: Patterson JW, editor, Weedon’s Skin Pathology. 4th ed. Churchill Livingston Elsevier; 2016. p. 837-901