It has been said that the best “special stain” is a deeper section – wise words indeed. While always gratifying to discover pathology not present on original sections, it is also humbling to ponder the number of incorrect diagnoses because deeper sections are not obtained. As a typical slide will demonstrate less than 2% of the specimen’s pathology, examining the most informative sections is crucial, especially for pigmented lesions.
Ex vivo dermoscopy (EVD) as an ancillary method of gross pathology serving to guide tissue sectioning was first described by Scope et al. The authors used noncontact polarized dermoscopy, comparing pigmented lesions prior to excision (in vivo) to the excised specimen that was in formalin for at least 6 hours (ex vivo). The findings were comparable between in vivo and ex vivo images, leading to the conclusion that utilizing these images could help determine the appropriate site to section specimens, thereby improving patient care (1).
Amin and Fraga reviewed 517 cutaneous biopsies with corresponding EVD images to determine whether EVD provides useful ancillary information in the histopathologic diagnosis of melanocytic neoplasms. Four hundred eighty-three cases (93.4%) yielded usable images. The lesions could be categorized according to a published dermoscopic classification system of melanocytic proliferations. Reticular pigmentation correlated with dysplastic nevi, globular pigmentation with congenital nevi, homogenous blue pigmentation with blue nevi, starburst peripheral globular pigmentation with Spitz nevi, and atypical pigment patterns with melanoma. Eighteen of 25 cases (72%) with ambiguous histopathology were assigned a more definite diagnosis when reviewed contemporaneously with EVD images. The surgical margins in 40 cases (7.7%) were reclassified when EVD images were included in the review. The authors found EVD to be a useful technique and advocated its use for diagnosis and clinical–pathologic correlation (2).
Hapeslagh et al performed a retrospective study comparing the diagnostic performance in 6526 skin biopsy specimens examined with a standard method of processing with 8584 biopsy specimens examined in with EVD and “Derm Dotting” (DD, marking the specimen with colored nail varnish). A total of 15 ,110 skin biopsy specimens were included. Use of EVD with DD increased the detection of positive section margins in nonmelanoma skin cancer from 8.4% to 12.8%. The most significant increase was seen in Bowen disease, invasive squamous cell carcinoma, and a superficial type of basal cell carcinoma (BCC). With EVD and DD, a specific clinicopathologic diagnosis was made in 27.7% of nevi compared with only 10.3% using the standard method. The incidence of moderately and severely dysplastic nevi increased from 1.0% to 7.2% and from 0.6% to 1.4%, respectively. The detection of ulceration in melanomas thicker than 1 mm increased from 24.0% to 31.3%. The number of nevi-associated melanomas increased from 15.5% to 33.3%. The number of collision lesions went from 0.07% to 1.07%. The authors suggested that pathologists involved in skin tumor evaluation should be encouraged to learn dermoscopy and replace random transverse cutting with lesion-specific and DD-guided cutting (3).
I recall my skepticism about dermoscopy, after listening to a lecture by Al Kopf more than 20 years ago, when he detailed “epiluminescence microscopy”. Why bother learning a technique if you were going to biopsy a lesion anyway? Today, I am glued to my dermatoscope (although I actually find it more valuable for non-pigmented than melanocytic lesions). Realistically, I do not look at every lesion with the dermatoscope, just choice lesions of concern. I would anticipate a similar scenario for EVD in the dermatopathology laboratory. It is the histotechnologist preparing the specimen – they would need to be taught the rudiments of EVD. For many routine specimens, performing EVD would be an extra step of questionable value. For lesions submitted as atypical nevi, however, perhaps an extra moment performing EVD would actually save time; a precise diagnosis on the first section obviates the need to prepare deeper sections.
As a clinician, I want to receive my reports as soon as possible. As a dermatopathologist, I prefer receiving the most representative sections initially (avoiding deeper sections), so EVD seems worthwhile. Because my slides are prepared by an outside laboratory, I will defer my dermatopathologist colleagues who run laboratories if they believe that EVD implementation is practical. I look forward to learning their perspectives.
* The image is from Maia et al (reference 4)
- Scope A, et al. Ex vivo dermoscopy of melanocytic tumors. Arch Dermatol 2007; 143: 1548-52.
- Amin K, Fraga GR. Ex vivo dermoscopy of cutaneous biopsies for melanocytic neoplasms: A retrospective review of 517 cases with histopathologic correlation. Am J Dermatopathol 2012; 34: 710-5.
- Haspeslagh M, et al. Pathologic evaluation of skin tumors with ex vivo dermoscopy with derm dotting. JAMA Dermatol 2017; 153; 154-60.
- Maia M, et al. Ex vivo dermoscopy: Synchronic evaluation between dermatologist and dermatopathologist of melanocytic lesions. An Bras Dermatol 2009; 84: 553-5.