[467] Reducing Block Sampling in Melanoma Re-Excision Specimens

Cassie Fives, Cynthia CBB Heffron. Cork University Hospital, Wilton, Cork, Ireland

Background: Wide local excisions (WLE) are frequently undertaken in the management of cutaneous melanoma, however, there is considerable variability between Histopathology departments in the macroscopic sampling of these common specimens and definitive College of American Pathologists or Royal College of Pathologist guidelines for sampling have not been established. The aim of our study was to establish evidence based guidelines for the macroscopic handling of these specimens with a subsequent review of the impact on our service following their implementation.
Design: The study group comprising of 128 cases which underwent initial biopsy and subsequent WLE in our institution in 2010 were identified by a computer generated search. From the analysis of this group we derived our guidelines for macroscopic sampling. A repeat search was performed over a six month period in 2012 following the implementation of our recommendations to review the impact these guidelines had on our service. We recorded details of the macroscopic appearance, number of blocks sampled and margins of the original biopsy.
Results: In our original study group a wide variation in block numbers sampled (range 1-27) was noted with an average 7.5 blocks submitted per case. Residual melanoma was identified in 7 of the cases (5.5%) with clear margins on the original biopsy. Of these, four had a pigmented lesion on macroscopic examination and the remaining 3 had margins of ≤1mm on the original excision. No case required further surgery. Based on this, our recommendations were, if the margin of the original biopsy was clear by >1mm and no macroscopic abnormality was noted grossly a maximum of 3 blocks was to be submitted, if a pigmented lesion was present or original margins were involved more extensive sampling was advised. On review six months following the implementation of our guidelines we saw an overall block reduction of 36% with an average 2.7 block reduction per case. Even with our reduced sampling, our rates of residual melanoma in the WLE remained comparable with residual melanoma only being detected in those cases with positive original margins, margins <1mm or with a pigmented lesion.
Conclusions: We have shown that for WLE specimens with no evidence of a macroscopic lesion and in which margins of the original biopsy were clear by ≥1mm, little is to be gained from extensive sampling. In these cases, we recommend a maximum of 3 blocks per case. Reduction in sampling based on this evidence would result in saving valuable laboratory resources in already overworked Histopathology departments.
Category: Dermatopathology

Tuesday, March 5, 2013 9:30 AM

Poster Session III # 55, Tuesday Morning

 

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