Dores C B, Milovancev M, Russell D S
Department of Biomedical Sciences, Oregon State University, Corvallis, Oregon.
Department of Clinical Sciences, Oregon State University, Corvallis, Oregon.
Vet Comp Oncol. 2018 Mar;16(1):125-130. doi: 10.1111/vco.12321. Epub 2017 May 23.
Radial sections are widely used to estimate adequacy of excision in canine cutaneous mast cell tumours (MCTs); however, this sectioning technique estimates only a small fraction of total margin circumference. This study aimed to compare histologic margin status in grade II/low grade MCTs sectioned using both radial and tangential sectioning techniques.
A total of 43 circumferential margins were evaluated from 21 different tumours. Margins were first sectioned radially, followed by tangential sections. Tissues were examined by routine histopathology.
Tangential margin status differed in 10 of 43 (23.3%) margins compared with their initial status on radial section. Of 39 margins, 9 (23.1%) categorized as histologic tumour-free margin (HTFM) >0 mm were positive on tangential sectioning. Tangential sections detected a significantly higher proportion of positive margins relative to radial sections (exact 2-tailed P-value = .0215). The HTFM was significantly longer in negative tangential margins than positive tangential margins (mean 10.1 vs 3.2 mm; P = .0008). A receiver operating characteristic curve comparing HTFM and tangentially negative margins found an area under the curve of 0.83 (95% confidence interval: 0.71-0.96). Although correct classification peaked at the sixth cut-point of HTFM ≥1 mm, radial sections still incorrectly classified 50% of margins as lacking tumour cells. Radial sections had 100% specificity for predicting negative tangential margins at a cut-point of 10.9 mm.
These data indicate that for low grade MCTs, HTFMs >0 mm should not be considered completely excised, particularly when HTFM is <10.9 mm. This will inform future studies that use HTFM and overall excisional status as dependent variables in multivariable prognostic models.
放射状切片广泛用于评估犬皮肤肥大细胞瘤（MCT）切除的充分性；然而，这种切片技术仅估计了总切缘周长的一小部分。本研究旨在比较采用放射状和切线状切片技术对II级/低级别MCT进行切片时的组织学切缘状态。
对来自21个不同肿瘤的43个圆周切缘进行评估。先对切缘进行放射状切片，然后进行切线状切片。通过常规组织病理学检查组织。
43个切缘中有10个（23.3%）的切线状切缘状态与其放射状切片时的初始状态不同。在39个切缘中，9个（23.1%）分类为组织学无肿瘤切缘（HTFM）>0 mm的切缘在切线状切片时呈阳性。相对于放射状切片，切线状切片检测到的阳性切缘比例显著更高（精确双侧P值 = 0.0215）。阴性切线状切缘的HTFM显著长于阳性切线状切缘（平均10.1对3.2 mm；P = 0.0008）。比较HTFM和切线状阴性切缘的受试者工作特征曲线发现曲线下面积为0.83（95%置信区间：0.71 - 0.96）。尽管正确分类在HTFM≥1 mm的第六个切点处达到峰值，但放射状切片仍将50%的切缘错误分类为无肿瘤细胞。放射状切片在切点为10.9 mm时预测阴性切线状切缘的特异性为100%。
这些数据表明，对于低级别MCT，HTFM>0 mm不应被视为完全切除，特别是当HTFM<10.9 mm时。这将为未来在多变量预后模型中使用HTFM和整体切除状态作为因变量的研究提供参考。
