Exhaustive pathologic work-up in sentinel lymph node biopsy for melanoma: is it necessary?

Abstract

The objective of this study is to determine whether a less exhaustive pathologic work-up to detect melanoma metastasis is clinically useful and does not affect patient prognosis. The success and evolution of the sentinel lymph node (SLN) depends on histological techniques. Several exhaustive protocols of SLN analysis have been published, but are time and cost consuming, with slight increases in the rates of metastasis detection. From 281 patients with SLN biopsy, each SLN was sectioned every 2 mm and from each paraffin block, 2-3 histological sections were evaluated. The patients were divided as follows: the first group (n=185) was subjected to extensive SLN examination (eSLNe) and the second group (n=96) was not subjected to an extensive SLN examination (wSLNe). The average SLN resected was 2 (range: 1-7), evaluating one in 50.9%. The SLN metastasis detection rate was 28.5%, whereas eSLNe increased by 3.2%. During follow-up, 4/26 (17.4%) cases in the wSLNe group showed recurrence in the SLN basin. Factors associated with decreased survival in univariant analysis were recurrence, Breslow thickness, advanced clinical stage, ulceration, and SLN metastasis. eSLNe did not affect disease-specific survival. Multivariate analysis showed recurrence (hazard ratio 23.475, 95% confidence interval: 1903-4559, P<0.001) and Breslow thickness of more than 3.5 mm (hazard ratio 15.222, 95% confidence interval: 1448-3059, P<0.001) as independent risk factors for decreased survival. Our routine for SLN examination enabled an adequate rate of SLN metastasis detection and the eSLNe increased the rate of detection in 3.2%, but did not affect the survival. We did not find any benefit from performing the eSLNe in patients with Breslow thickness less than 3.5 mm.

Sentinel lymph node assessment in melanoma: current state and future directions

“…Currently, institutional protocol for histopathological handling of sentinel lymph nodes and pathological reporting varies widely. 68,128,129,130,131,132 Macroscopically, two main methods of slicing sentinel lymph nodes exists: 'breadloafing', allowing for better examination of the subcapsular region, and bivalving, allowing for better examination of lymphatic vessels. 130,131 Both the European Organisation for Research and Treatment of Cancer (EORTC) and Sydney Melanoma Unit recommend the utilisation of the bivalving technique in sentinel lymph node histopathological and handling protocol.…”

“…68 The process of IHC staining, which may augment prognostication, is time-consuming and labourintensive. 128,129 IHC has been shown to mildly increase metastatic tumour detection rates in sentinel lymph nodes, but whether these mild increases justify the time and cost of performing IHC is controversial. 129 One study found that, although extensive IHC work-up may increase detection rates, survival is unaffected.…”

“…129 One study found that, although extensive IHC work-up may increase detection rates, survival is unaffected. 128 Recent work into assessing BRAF V600E expression by IHC in capsular naevi found that, in patients with primary cutaneous melanoma, positive mutation is associated with increased tumour stage and lymph node metastasis, thus showcasing potential added value of IHC staining in SNLB. 85 It has been demonstrated that increased histopathological sampling increases detection rates.…”

“…Currently, institutional protocol for histopathological handling of sentinel lymph nodes and pathological reporting varies widely 68,128,129,130,131,132 . Macroscopically, two main methods of slicing sentinel lymph nodes exists: ‘breadloafing’, allowing for better examination of the subcapsular region, and bivalving, allowing for better examination of lymphatic vessels 130,131 .…”

“…IHC has been shown to mildly increase metastatic tumour detection rates in sentinel lymph nodes, but whether these mild increases justify the time and cost of performing IHC is controversial 129 . One study found that, although extensive IHC work‐up may increase detection rates, survival is unaffected 128 . Recent work into assessing BRAF V600E expression by IHC in capsular naevi found that, in patients with primary cutaneous melanoma, positive mutation is associated with increased tumour stage and lymph node metastasis, thus showcasing potential added value of IHC staining in SNLB 85 …”