Serial step sections at narrow intervals with immunohistochemistry are required for accurate histological assessment of sentinel lymph node biopsy in oral squamous cell carcinoma

Abstract

Background Sentinel lymph node (SLN) biopsy is an accurate staging modality in early oral squamous cell carcinoma (OSCC), but its accuracy relies on labor‐intensive histopathology protocols. We sought to determine whether serial step sections with immunohistochemistry (SSSIHC) at narrow intervals of the entire SLN are required to accurately exclude metastasis. Methods Consecutive SLN biopsies over a 13‐year period were retrospectively evaluated. If the index section was negative for carcinoma, the entire SLN was subjected to SSSIHC at 150 μm intervals. The first section level and total number of section levels to contain carcinoma were recorded. Results One hundred and eighteen SLN+ from 90 patients were included. SSSIHC upstaged the nodal status in 19.5% of patients. Metastasis was identified in 16.7% and 10.2% beyond section levels 4 and 6, respectively. Among SLNs requiring SSSIHC, 47.5% contained carcinoma in a single section level. Conclusion SSSIHC of the entire SLN at 150 μm intervals are required to identify occult metastasis in OSCC.

Centralised pathology service for sentinel node biopsy in oral cavity cancer: The Southeast England Consortium experience

“…In addition, the histological evaluation of sentinel nodes in OSCC requires exhaustive serial step sections with immunohistochemistry of the entire lymph node resulting in considerable labour and cost implications on histopathology departments. For example, recent findings from our group indicate that, on average, 128 slides are generated per SLNB case 16 . Given the labour‐intensive nature of histological evaluation of sentinel nodes in OSCC, it is unreasonable for pathology departments to subsume this work without appropriate additional equipment and staffing resources.…”

“…17,18 This study was approved by the Histological sentinel node assessment was undertaken as previously described. 16 Briefly, all sentinel nodes were sliced at 3 mm thickness and routinely processed. A single haematoxylin and eosin tumour deposits were classified as macrometastasis (deposits larger than 2 mm, Ma), micrometastasis (deposits of 200 μm-2 mm, Mi) or isolated tumour cells (ITC) (tumour deposits of <200 cells and/ or <200 μm, ITC).…”

“…However, due to logistic challenges such as training of the multidisciplinary team and compliance to stringent regulatory protocols, SLNB is currently only limited to a few centres. Furthermore, since histological evaluation of sentinel nodes requires serial step sections with immunohistochemistry of the entire lymph node, the considerable burden on pathology services limits the wide availability of this technique 15,16 …”

“…ments. For example, recent findings from our group indicate that, TA B L E 1 on average, 128 slides are generated per SLNB case 16. Given the labour-intensive nature of histological evaluation of sentinel nodes in OSCC, it is unreasonable for pathology departments to subsume this work without appropriate additional equipment and staffing resources.…”

“…Furthermore, since histological evaluation of sentinel nodes requires serial step sections with immunohistochemistry of the entire lymph node, the considerable burden on pathology services limits the wide availability of this technique. 15,16 The Southeast England Consortium for SLNB in OSCC was established in 2016 primarily for the purpose of widening the availability and providing quality assurance of the procedure. This model comprises four regional surgical head and neck cancer departments utilising a centralised pathology service.…”