Importance: In the era of targeted therapy for cancer, translational research identifying molecular targets in melanoma offers novel opportunities for potential new treatments.
Objectives: 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.
Results: 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.