A, In vivo dermoscopy (original magnification ×10). B, Ex vivo dermoscopic image of 4 dermoscopy-guided samples (2-mm punch), 2 of them for the histopathological correlation (the one on the left corresponds to dermoscopy in E and histological findings in F, and the one on the right corresponds to dermoscopy in H and histological findings in G). The 2 punch biopsies in the center were frozen and placed in the tissue bank. C, Dermoscopic mapping of the melanoma. D, Location of tissue sampling from within the melanoma. E, Ex vivo dermoscopic image with an atypical pigmented network with thick dark lines and a blue hue. F, Correlates on histopathological examination with a junctional proliferation of atypical melanocytes as solitary units and small nests and with the presence of melanophages in the superficial dermis (hematoxylin-eosin, original magnification ×100). G, Histopathological correlation of the area in H reveals nests of atypical melanocytes in the epidermis and along the dermoepidermal junction (hematoxylin-eosin, original magnification ×100). H, Ex vivo dermoscopic image of an area that exhibits brown globules with a negative network.
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Malvehy J, Aguilera P, Carrera C, et al. Ex Vivo Dermoscopy for Biobank-Oriented Sampling of Melanoma. JAMA Dermatol. 2013;149(9):1060–1067. doi:10.1001/jamadermatol.2013.4724
In the era of targeted therapy for cancer, translational research identifying molecular targets in melanoma offers novel opportunities for potential new treatments.
To describe a method for sampling fresh tissue from primary melanoma and to test whether the area of maximal thickness can be identified with dermoscopy to ensure it remains available for routine histopathological diagnosis.
Design, Setting, and Participants
Tumors clinically suspicious for melanoma with diameter exceeding 5 mm were included. Dermoscopy-guided sampling was performed using a 2-mm to 3-mm punch through not the thickest part of the tumor. In vivo and ex vivo dermoscopic images obtained were available to the diagnosing pathologist. Melanoma samples were obtained in a referral melanoma unit.
Main Outcomes and Measures
In study 1, Breslow thickness in 10 melanomas was compared between sampled tissue and the remaining specimen to confirm that the area of maximal thickness remained available for the histopathological diagnosis. In study 2, forty-three additional melanomas were sampled for biobanking prospectively. Agreement between 2 independent observers on dermoscopic identification of the thickest part of the melanoma was studied.
In study 1, the area of maximal Breslow thickness in all 10 melanomas was not sampled and remained in the main specimen. In study 2, sampling was performed by one of the investigators. Concordance was 93% between 2 independent observers for the dermoscopic selection of the thickest portion of the melanoma. Pathologists asserted that the sampling procedure did not compromise their ability to evaluate melanoma specimens. A limitation is that this is a single-center study. Each case required joint evaluation by expert dermoscopists and dermatopathologists.
Conclusions and Relevance
In applying the dermoscopy-guided sampling protocol, we make the following 5 recommendations: Samples should only be obtained from areas that will not interfere with the pathologist’s diagnosis and prognostic information. Sampling should not be obtained from tumors for which one suspects that the histopathological evaluation may prove difficult. Sampling should not be performed on small melanomas; we recommend a minimum diameter of 10 mm. All the dermoscopy-guided sampling should be documented with images, available to pathologists and clinicians, and reflected in the pathology report. Finally, the frozen biobank samples should be made available for routine hematoxylin-eosin histopathological evaluation until the final pathology report is produced. Ex vivo dermoscopy may serve to guide the procurement of small samples from primary melanoma for fresh tissue biobanking without compromising the histopathological evaluation.
In the era of targeted therapy for cancer, translational research identifying molecular targets in melanoma offers novel opportunities for potential new treatments. Quiz Ref IDThere is increasing evidence at the molecular level that melanoma is composed of distinct mutational subsets,1 each harboring different potential targets for therapy.2 Fresh or frozen tissue is required for the performance of cellular studies (including tissue cultures from primary tumors) and molecular studies (including genomics and proteomics) and for the design and production of biologic treatments. The aforementioned studies cannot be adequately conducted on formalin-fixed, paraffin-embedded samples.3,4 Needless to say, the development of fresh-frozen tissue banks procured from primary melanomas will likely lead to heightened translational research and may greatly influence diagnosis, prognosis, and therapeutic strategies in the coming years.
Histopathological study of formalin-fixed, paraffin-embedded specimens is crucial for the diagnosis and staging of melanoma.4,5 The risk in randomly procuring samples from freshly excised melanoma specimens for biobanking is that the remaining specimen, which is submitted for formalin-fixed, paraffin-embedded examination, could sustain damage that would preclude adequate histopathological processing. In addition, the random removal of tissue may compromise the ability of the pathologist to evaluate and adequately diagnose the remaining specimen on routine histopathological examination, with untoward clinical and medicolegal consequences.6,7 In a previous study,8 researchers evaluated a method for the procurement of fresh tissue from excisional specimens of melanocytic nevi based on examination with the naked eye; they concluded that the procurement of fresh tissue for research had no influence on the final diagnosis. A method has been described for the use of ex vivo dermoscopy for gross pathological evaluation in the histopathology laboratory.9 Subsequently, ex vivo dermoscopy was used in 517 cutaneous biopsy specimens,10 determining that it provides useful ancillary information for the histopathological diagnosis of melanocytic neoplasms. Indeed, dermoscopy can be useful for guiding tissue sectioning for the histopathological correlates,11-18 and certain dermoscopic structures can be used to predict melanoma thickness.19,20
Quiz Ref IDGiven the added value of dermoscopy for performing gross pathological evaluation of melanocytic neoplasms and for predicting microscopic findings on the histopathological examination, we reasoned that dermoscopy can be used to select areas within excisional specimens that could be safely removed for molecular studies without compromising the histopathological evaluation of the specimen. This idea prompted us to explore the use of dermoscopy as an ancillary method for guiding and precisely documenting the procurement of fresh tissue from primary melanoma excisional specimens for molecular research.
The protocol of ex vivo dermoscopy-oriented sampling of melanoma (DOS-M) was approved by the institutional review board at the Hospital Clinic, Barcelona, Spain. The study setting was an outpatient clinic specializing in melanoma diagnosis and treatment in a tertiary medical center. Within this framework, inclusion criteria for the study were the following: (1) a lesion for which the most likely diagnosis, based on clinical and dermoscopic criteria, was primary cutaneous melanoma; (2) the clinically measured diameter of the lesion exceeded 5 mm in greatest length and width; and (3) informed consent was given by the patient. Exclusion criteria were the following: (1) a lesion for which it was anticipated that the histopathological evaluation may prove problematic or difficult (eg, dermoscopic criteria suggestive of a spitzoid neoplasm) and (2) patients younger than 18 years.
The entire protocol described below is also depicted via a series of images from a melanoma (Figure). Six components of the study protocol include the following:
First, all eligible lesions were evaluated with dermoscopy before surgery (in vivo dermoscopy). Areas of interest for sampling within the lesions were identified.
Second, lesions were surgically excised with narrow margins. These were 2 mm or 5 mm, according to routine practice.
Third, dermoscopy was used on the freshly excised specimen (ex vivo dermoscopy) to identify the previously identified (in vivo) areas of interest for sampling. Tissue samples were incised from within the excisional specimen using a 2-mm to 3-mm punch (Figure) according to the size of the tumor; a 3-mm punch was used when the diameter exceeded 20 mm. Areas anticipated as being the thickest portion of the lesion (see the evaluation of melanoma thickness below under the Study 1 and Study 2 subheadings) were not sampled by incision but were preserved for the assessment of Breslow thickness during the histopathological analysis. For example, if a nodule was identified within the melanoma, only the peripheral part of the nodule was incised for fresh tissue sampling, while the center of the nodule, predicted to be the thickest part, was preserved for the histopathological analysis. Incisional sampling was also not obtained from areas showing dermoscopically equivocal findings that precluded the prediction of thickness.
Fourth, the excisional specimen was submitted for routine pathology laboratory processing. Excised tissue specimens underwent routine formalin fixation and paraffin embedding; vertical sections were stained with hematoxylin-eosin (H&E). The final histopathological diagnosis was based on the evaluation of slides obtained from step-sectioning of the remaining excisional specimens. All histopathological slides were evaluated by at least 2 pathologists (J.P. and L.A.) and analyzed for mitoses, Clark level, Breslow thickness, neural invasion, lymphatic invasion, type of inflammatory infiltrate, growth phase (radial vs vertical), and the presence of ulceration, regression, and microsatellites.
Fifth, incised tissue samples were embedded in formalin in study 1 (comparison of Breslow thickness between incised samples and the remaining specimen). Alternatively, they were cryopreserved at −80°C for biobanking in study 2 (dermoscopic agreement study).
Sixth, all cases were discussed during a clinicopathological conference (CPC), in the presence of the dermatologists and pathologists (J.P. and L.A.) involved in the study, to determine whether incisional sampling of the melanoma could adversely influence the diagnosis and staging of the melanomas. The frozen samples of the melanomas were not processed for molecular studies until after the participants of the CPC had reached a consensus decision that H&E histopathological analysis of the frozen samples was unlikely to change the diagnosis or staging of the melanoma.
We obtained clinical and contact polarized dermoscopic images of all primary melanomas included in the study to precisely document sampling of tissue from within the lesions (Figure). Images of the melanomas were acquired in the following sequence: (1) before surgical excision (clinical and in vivo dermoscopic images), (2) immediately after surgical excision (ex vivo dermoscopic images), and (3) after obtaining incisional punch samples from within the excised melanoma specimen (ex vivo dermoscopic images). All ex vivo images were acquired before formalin fixation of specimens.
Images were obtained with a camera (PowerShot G7; Canon Inc or CoolPix 4500; Nikon Inc). All in vivo dermoscopic images were captured using the same cameras attached to a polarized contact dermoscopic lens (DermLite Foto; 3GEN, LLC). During ex vivo contact dermoscopic photography, the excised specimen was covered with a sterile plastic wrap (transparent wrap used for instrumental or dressing sterilization) to avoid contamination of the lens. As described by Zampino and coworkers,21,22 we affirm that obtaining the dermoscopic images through a plastic wrap does not alter image quality.
In addition to the clinical and dermoscopic images, a schematic drawing of the lesion was generated before formalin fixation (Figure) to annotate the sites of tissue sampling within the excised melanoma specimen. Annotation included a description of the clinical findings (colors, ulceration, and mapping of flat areas or papules or nodules) and the dermoscopic features (specifically, ulceration, blue-white veil, and atypical vessels).
All clinical and dermoscopic images and schematic drawings were sent to the pathology laboratory together with the formalin-fixed specimens. Special attention was given to the identification and annotation of areas within the melanoma that were predicted to have the greatest Breslow thickness in the histopathological analysis; these areas were clearly marked in the in vivo dermoscopic image and in the schematic drawing of the melanoma to guide the gross pathological examination in the pathology laboratory (Figure).
As a proof of principle, study 1 tested the notion that the thickest portion of the melanoma can be preserved for the histopathological examination based on gross (clinical and dermoscopic) assessment before the procurement. In a subset of 10 melanomas, the incisional punch samples were not cryopreserved for biobanking but rather were submitted for routine histopathological analysis with the remaining excisional specimen. The Breslow thickness of the incisional punch samples was compared with the maximal Breslow thickness measurement of the remaining excisional specimen.
Study 2 determined agreement between 2 independent observers on dermoscopic identification of the thickest part of the melanoma. This study was performed on 43 additional melanomas.
The prediction of the thickest portion was based on gross evaluation (clinical and dermoscopic) of the melanoma using criteria previously defined by Argenziano et al.19 According to this method, the thickest parts of the melanoma correlate clinically and dermoscopically. Clinically, the thickest parts correlate with (1) nodular parts of the tumor and (2) areas of ulceration. Dermoscopically, the thickest parts correlate with (1) gray-blue areas, also known as blue-white veil, that correspond to irregular, confluent, gray-blue diffuse pigmentation present focally within the lesion (ie, does not occupy the entire surface area of the lesion) and (2) areas showing an atypical vascular pattern, particularly in hypomelanotic melanomas.
To test the reproducibility of the prediction of the thickest portion of melanoma, an interobserver agreement study was performed. Specifically, in vivo and ex vivo images of 43 melanomas were mapped using a digital grid constructed for the study, which divided the melanoma into numbered blocks. These images were evaluated by 2 independent observers (G.S. and L.L.), who were asked to select the block most likely to contain the thickest part of the melanoma.
Implementation of the DOS-M protocol is contingent on good bedside (in vivo) to bench (ex vivo) concordance on the identification of the morphological attributes of the melanoma. To test this concordance, we performed an interobserver agreement study between dermoscopic features identified in vivo and ex vivo. The 2 sets of dermoscopic images were separately analyzed for global dermoscopic pattern, the distribution of dermoscopic structures (asymmetry), the presence of colors (light brown, dark brown, black, blue-gray, white, pink, and red), and the presence of dermoscopic structures (blue-white veil, atypical vessels, regression structures, atypical pigment network, atypical dots and globules, streaks or atypical streaks, and blotches or atypical blotches).
Descriptive statistics were used to characterize the histopathological attributes of included melanomas. To compare the findings of in vivo and ex vivo dermoscopy in study 2, correlation statistics (Spearman rank correlation coefficient and Pearson product moment correlation R and κ) were calculated. A κ statistic exceeding 0.8 denotes excellent correlation, while a κ statistic of less than 0.2 is considered poor correlation.
Ten consecutive melanomas, diagnosed at the melanoma clinic, were included in study 1 and processed using the DOS-M procedure of dermoscopy-guided tissue sampling (Table 1). The study set comprised 9 invasive melanomas with a mean Breslow thickness of 2.25 mm (range, 0.55-6.00 mm) and 1 in situ melanoma. Of 9 invasive melanomas, 7 were superficial spreading, 1 was acral lentiginous, and 1 was a desmoplastic melanoma arising in a lentigo maligna melanoma. Histopathologically identified ulceration was present in 2 of the melanomas. Two blinded pathologists evaluated both parts of each tumor. Quiz Ref IDThe maximal Breslow thickness was measured and compared between the incised sample and the remaining main tissue specimen for each of 10 melanomas. In all 10 melanomas, the area of maximal Breslow thickness was not sampled and remained in the main tumor specimen.
Forty-three consecutive melanomas were prospectively included in study 2 and processed using the DOS-M procedure (Table 2). The mean clinical diameter of the melanomas (in the smaller dimension) was 16.5 mm (range, 6.0-41.0 mm). In the histopathological analysis, the study set comprised 35 invasive melanomas (81%) with a mean Breslow thickness of 1.49 mm (median, 1.10 mm; range, 0.40-5.40 mm) and 8 in situ melanomas (19%). Histopathologically identified ulceration was present in 4 of 43 melanomas (9%). Of 35 invasive melanomas, 29 (83%) were classified as superficial spreading melanoma, 4 (11%) as nodular melanoma, 1 (3%) as acral lentiginous melanoma, and 1 (3%) as lentigo maligna melanoma.
Two independent observers (G.S. and L.L.) retrospectively analyzed the dermoscopic images from each melanoma and selected the sector on the study grid most likely to contain the thickest part of the melanoma. Concordance was 93% on the selection of the sector likely to be the thickest.
Dermoscopic attributes were compared between in vivo and ex vivo images of the melanomas (Table 3). Quiz Ref IDThere was excellent agreement (κ > 0.8) on the categorization of global dermoscopic pattern, the distribution of dermoscopic structures (asymmetry), the presence of colors (light brown, dark brown, black, blue-gray, and white), and the presence of dermoscopic structures (streaks, blue-white veil, regression structures, atypical dots and globules, atypical pigment network, and blotches or atypical blotches). Poor correlation (κ < 0.2) was observed for the presence of atypical vessels and the finding of pink or red; blood vessels and vascular blush were not observable under ex vivo dermoscopy.
All 43 melanomas included in study 2 were jointly analyzed at a CPC to determine whether incisional sampling of the melanoma could adversely influence the diagnosis and staging of the melanomas. Although all frozen incisional samples were readily available from the tissue bank and, if needed, could have been subjected to H&E histopathological assessment, the consensus opinion by participating pathologists and dermatologists was that this was unlikely to change the diagnosis and final staging for any of the melanomas included in study 2.
This study introduces the use of dermoscopy for guiding tissue sampling. Dermoscopy can serve as a bridge between clinicians and pathologists because it provides a gross pathological map of the melanoma, available both at the bedside (in vivo) and pathology bench (ex vivo).10 Indeed, the findings reported herein suggest that dermoscopic evaluation and imaging of tissue can be performed ex vivo, with proficiency comparable to that of in vivo dermoscopy, and that the dermoscopic images can be used to create a tumor map, which in turn can serve as a guide for fresh tissue sampling.
In addition, the present study supports prior observation that dermoscopic criteria for tumor thickness can be applied in a reproducible manner.18 High concordance was shown between 2 independent observers in the clinical and dermoscopic identification of the thickest area of the melanomas. Furthermore, the area with maximal Breslow thickness of the melanoma was shown to be retained within the excised melanoma specimen under the DOS-M technique. Indeed, in a subset of 10 melanomas, the incised samples were submitted for routine H&E histopathological analysis (rather than being diverted to biobanking) and were shown to be thinner in Breslow thickness than the remaining main excisional specimen. Experience in dermoscopy is required to perform gross thickness evaluation to minimize the risk that sampling will remove portions of the melanoma that are important for the final diagnosis and staging.
For the DOS-M protocol described herein, it is important to precisely document areas sampled by annotating the dermoscopic images and schematics (Figure); these documents should be included in the report sent to the tissue bank registry and to the pathology laboratory registry. This allows clinicians and pathologists to know exactly which parts of the melanoma were sampled and which parts of the melanoma were available for routine H&E processing. The prepathological sampling of the lesion using the DOS-M method should be reflected in the pathology report. The successful implementation of the DOS-M protocol is contingent on having an interactive and collegial multidisciplinary research team composed of dermatologists, surgeons, pathologists, and biologists. In the present study, while the cryopreserved procured tissues were available for H&E histopathological analysis, our pathologists did not deem it necessary to use them in rendering a final histopathological diagnosis. They reasoned that dermoscopy-guided sampling and availability of precise documentation of the gross pathological examination probably lead to comparable, if not better, sampling of melanoma compared with routine, blinded, mostly random tissue gross pathological examination.
At present, this procedure should be restricted to experienced research centers with a well-defined protocol that will ensure the precise diagnosis and staging of patients. Nevertheless, highly specialized skin pathology providers might embrace similar protocols in the future.
In applying the DOS-M protocol, we note the following 5 points: (1) Samples should only be obtained from areas that will not interfere with the pathologist’s ability to render a definitive diagnosis and to provide accurate prognostic information. (2) Sampling should not be obtained from tumors for which one suspects that the histopathological evaluation may prove difficult or for which the evaluation of the entire tumor would be crucial (eg, dermoscopically equivocal lesions, melanoma arising in a nevus, and lesions with extensive regression). (3) Sampling should not be performed on small melanomas; we recommend a minimum diameter of 10 mm because sampling from larger melanomas leaves behind sufficient tissue for the histopathological evaluation. (4) A CPC should be held regularly to review the cases together with the clinical images, in vivo and ex vivo dermoscopy images, and the annotated maps. (5) The procured frozen biobank tissue samples for molecular analyses should be made available for routine H&E histopathological evaluation until the final pathology report is produced if deemed necessary by CPC consensus.
Our study has limitations. First, the single-study includes few cases. Second, the determination of Breslow thickness among incisional samples was only performed for a subset of the melanomas. Third, only lesions recognized clinically and dermoscopically as likely melanomas were included. If molecular studies are to be used for the differentiation of melanoma from benign lesions, sampling should probably also include cases with an equivocal diagnosis.
In conclusion, we have developed a technique for dermoscopy-guided sampling of small portions of any given melanoma. Quiz Ref IDThis technique is the first step in sampling melanomas for the purpose of biobanking freshly excised tissue for molecular studies. Dermoscopy can be applied ex vivo to freshly excised tissues, with the findings comparable to those of in vivo examination. The thickest portion of the melanoma can be reproducibly identified and documented under the DOS-M protocol, allowing incisional sampling of areas within the melanoma that would not compromise the final histopathological diagnosis and staging. Finally, it is fundamental to restrict this DOS-M procedure to medical centers with an interdisciplinary team composed of clinicians with expertise in dermoscopic evaluation of melanoma and of dermatopathologists with expertise in the evaluation of melanocytic neoplasms. In our experience, such a strategy translates to better communication among dermatopathologists, clinicians, and researchers.
Corresponding Author: Susana Puig, MD, Melanoma Unit, Department of Dermatology, Hospital Clinic, Institut d’Investigacions Biomèdiques August Pi i Sunyer, Calle Villarroel 170, 08036 Barcelona, Spain (firstname.lastname@example.org).
Published Online: July 17, 2013. doi:10.1001/jamadermatol.2013.4724.
Author Contributions: Drs Malvehy, Aguilera, Lovatto, and Puig had full access to all the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
Study concept and design: Malvehy, Puig.
Acquisition of data: Malvehy, Aguilera, Carrera, Salerni, Lovatto, Palou, Alós, Puig.
Analysis and interpretation of data: Malvehy, Salerni, Scope, Marghoob, Palou, Alós, Puig.
Drafting of the manuscript: Malvehy, Aguilera, Puig.
Critical revision of the manuscript for important intellectual content: Malvehy, Salerni, Lovatto, Scope, Marghoob, Palou, Alós.
Statistical analysis: Malvehy, Aguilera, Salerni, Puig.
Obtained funding: Malvehy, Puig.
Administrative, technical, and material support: Malvehy, Lovatto.
Study supervision: Malvehy.
Conflict of Interest Disclosures: None reported.
Funding/Support: The research at the Melanoma Unit is partially funded by grants 03/0019, 05/0302, 06/0265, and 09/01393 from Fondo de Investigaciones Sanitarias; by the Centro de Investigacion Biomedica en Red Enfermedades Raras of the Instituto de Salud Carlos III; by the AGAUR 2009 SGR 1337 of the Catalan Government; by contract LSHC-CT-2006-018702 (GenoMEL) from the European Commission under the 6th Framework Programme; and by grant CA83115 from the National Cancer Institute, National Institutes of Health.
Role of the Sponsors: The sponsors had no role in the design or conduct of the study; in the collection, analysis, or interpretation of data; or in the preparation, review, or approval of the manuscript.
Additional Contributions: This work was performed with the participation of the following other members of the Melanoma Unit: Llúcia Alós, MD, Ana Arance, MD, Pedro Arguís, MD, Antonio Campo, MD, Teresa Castel, MD, Carlos Conill, MD, Daniel Gabriel, MD, Pablo Iglesias, MD, Jose Palou, MD, Ramon Rull, MD, Marcelo Sánchez, MD, Sergi Vidal-Sicart, MD, Antonio Vilalta, MD, and Ramon Vilella, MD. Helena Kruyer, PhD, assisted with the English-language editing of the manuscript. We are grateful to all the clinicians who referred the patients to our unit, the fellows involved in the project, and those patients who kindly agreed to allow us to image and sample their tumors and use them for scientific purposes.
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