Abstract
The aim of this research was to determine the pathologic invasion of the carotid sheath (CS) when found grossly uninvolved during surgery, in patients undergoing neck dissection for head and neck squamous cell carcinoma (HNSCC). A prospective study was undertaken in 70 consecutive patients with biopsy proven HNSCC, without prior history of any treatment, undergoing neck dissection, in whom the CS was found grossly uninvolved intra-operatively, were included. A total of 80 neck dissections were performed. Supra-omohyoid neck dissections for clinically N0 neck and appropriate modified radical neck dissections for clinically N+ neck were carried out. 129 CS were dissected separately and thoroughly examined by well trained head and neck pathologists for tumour infiltration and the presence of lymphatic tissue. On microscopic examination, 27 patients were N0 status and the remaining 43 (61.4%) had at least one metastatic lymph node (N+). None of 129 CS specimens show the presence of normal lymphatic tissue or metastatic tumour deposits. The authors think that avoiding resection of the CS in the absence of gross invasion by nodal disease is possible without jeopardising oncologic safety. A preserved CS might offer protection to the important neurovascular structures and reduce significant morbidity.
Cervical lymph node metastasis is one of the most important prognostic factors in head and neck squamous cell carcinoma (HNSCC). An appropriate neck dissection is an integral part of the surgical treatment of HNSCC. Inadequate removal of lymphatic structures predisposes to recurrence in the neck even after multimodality treatment. It is a routine practice to excise the carotid sheath (CS) completely as a part of the neck dissection procedure because it is reported to harbour lymph nodes and lymphatic channels. Extreme care is taken to preserve the pre-vertebral fascia which provides a floor for the fibro-fatty-lymphatic tissue of the neck.
The differential approach to the similar fascias in the neck is intriguing. Little has been reported to document the actual pathological infiltration of the CS when grossly un-involved intra-operatively. Working in a tissue plane between CS and the neurovascular structures of the neck may lead to a higher chance of damage to these structures. CS is a strong fibro-elastic tissue barrier which shields the internal jugular vein and carotid artery from saliva or local infection in the postoperative period. Complications, such as rupture of the internal jugular vein and rarely carotid artery, have been known to occur subsequent to salivary leak and infection in the neck, which may lead to significant morbidity and even mortality.
The authors undertook this prospective study to document the incidence of pathological involvement of the CS when it is clinically uninvolved in patients undergoing neck dissection for HNSCC.
Materials and methods
This prospective study was undertaken in 70 consecutive patients (57 males, 13 females), aged 21–70 years (mean 54 years) with biopsy proven HNSCC undergoing neck dissection and in whom the CS was found grossly uninvolved intra-operatively. Patients with gross infiltration of the sheath or a grossly involved node close to the sheath, which necessitated removal of the sheath for oncological safety, were excluded from the study as were patients who had previously undergone chemotherapy, radiotherapy or surgery to the neck. 10 patients underwent bilateral neck dissections so a total of 80 neck dissections were analysed. Patients with necks of clinical N0 status were subjected to supra-omohyoid neck dissections whilst for those with clinical N+ necks, appropriate modified radical neck dissections were performed. 64 patients had the primary in the oral cavity, 4 had laryngeal cancers and 2 were diagnosed with nodal metastases from an unknown primary in the head and neck region ( Table 1 ).
| Primary tumour site | Number of patients |
|---|---|
| Buccal mucosa complex | 40 (57.14%) |
| Tongue | 24 (34.28%) |
| Larynx | 04 (5.7%) |
| Unknown primary | 02 (2.8%) |
| Pathological tumour stage | |
| Unknown primary in HNSCC | 02 (2.8%) |
| pT1 | 04 (5.7%) |
| pT2 | 10 (14.28%) |
| pT3 | 08 (11.42%) |
| pT4 | 46 (65.71%) |
| Pathologic nodal stage | |
| pN0 | 27 (38.57%) |
| pN1 | 16 (22.85%) |
| pN2a | 03 (04.28%) |
| pN2b | 17 (24.28%) |
| pN2c | 07 (10%) |
| pN3 | 00 |
In patients with laryngeal primary, appropriate bilateral neck dissections were performed. As a first step, the neck dissection was completed sparing the carotid sheath in its entire length. The authors did not find any technical difficulty in performing a CS sparing neck dissection due to the presence of a distinct plane of cleavage. Later, the CS was stripped off its contents separately with sharp scissors and separated into superior and inferior components (with reference to the upper and lower halves of the internal jugular vein (IJV)) ( Fig. 1 ). It was fixed in 10% formalin and sent for histopathology examination at the department of pathology at the authors’ facility. 129 CS specimens were collected in this study. In some patients who had supra-omohyoid neck dissections, the authors sampled only CS adjacent to the upper half of the IJV. In patients undergoing modified neck dissections, superior and inferior parts were sampled.
The specimens were processed routinely and microsections (5 μm) were stained with haematoxylin–eosin. Histopathology was carried out by a team of three senior head and neck pathologists at the authors’ facility.
Results
Histopathological characteristics such as tumour size, the presence of metastatic nodes, and extracapsular spread were studied. All the CS specimens were examined for tumour infiltration and the presence of lymphatic tissue. 46 patients had advanced (pT4) primary tumour. On microscopic examination, 27 patients showed absence of metastatic neck nodes (pN0) whilst the remaining 43 (61.4%) had lymph node involvement (pN+) with 7 (10%) having bilateral cervical nodal metastases. Of these 43 patients with nodal metastases, 32 had extracapsular spread of disease ( Table 1 ). None of the 129 CS specimens showed the presence of lymphatic tissue harbouring malignant cells. All the CS sections were reported as fibro-fatty tissue only. There was no evidence of dilated lymphatic channels/lymphatic emboli. Normal lymphatic aggregates/lymph nodes and neutrophilic or lymphocytic infiltration of CS was absent in all ( Fig. 2 ).
