Lymph node metastasis in auricular squamous cell carcinoma

Clark, Richard R. (2009) Lymph node metastasis in auricular squamous cell carcinoma. MD thesis, University of Glasgow.

Abstract

Introduction
Squamous cell carcinoma of the auricle has an unusually high rate of lymph node metastases when compared to similar tumours at other sites. The lymph nodes affected are close to the base of the skull and in the neck. Development of metastasis carries a poor prognosis and most patients will subsequently die of failure of loco-regional control. Despite the likelihood of a poor outcome nothing can be done for patients prior to development of metastasis, as the risk of spread is not sufficiently high to warrant intervention in all patients. They are therefore treated with a ‘wait and see policy’ and only offered treatment once clinical evidence of metastatic spread is detected.
This thesis sets out to examine what can be done, at the time of initial presentation with an auricular squamous cell carcinoma to identify patients who would benefit from treatment to the regional lymph node basins.
Materials and Methods
The thesis is divided into four separate studies. A systematic review examines the evidence available to date, an anatomical study examines the lymphatic drainage of the auricle in cadavers, a sentinel lymph node biopsy study examines the use of this technique to identify early tumour spread and a retrospective analysis of cases of auricular squamous cell carcinoma in our unit examines histopathological prognostic indictors of metastatic spread.
Results
The systematic review found that these tumours have a metastatic rate of about 11%. Patients developing metastasis usually die from failure of loco-regional control. Depth of tumour invasion, tumour size and mode of invasion seem to be potential indicators of metastatic risk. There is a strong argument for prophylactic intervention to the regional lymph nodes but there is no consensus of opinion as to when this should be carried out
The anatomical study comprised 5 cadaveric dissections. They showed that the first echelon nodes draining the auricle lie in the superficial parotid gland, post-auricular/ mastoid nodal group and level II of the neck. There are anastamotic pathways around the mastoid and post-auricular nodes that could permit embolic tumour cells to bypass them. Five lymphatic pathways draining the auricle are described and some of these lie on the lateral and anterior surfaces of the mastoid bone and traverse the insertion of sternocleidomastoid.
28 cases of auricular squamous cell carcinoma were enrolled for sentinel lymph node biopsy. None of them were found to have any metastatic spread. One case showed non-viable tumour cells in a lymph node. There was a high incidence of complications (14%) directly related to the sentinel node biopsy procedure.
The retrospective analysis identified 229 cases of auricular squamous cell carcinoma treated in our unit from 1992 - 2004. 212 of these cases had the primary pathology available for analysis. 24 (of 212) patients developed metastasis. 17 patients died as a result of their disease usually due to failure of control at the regional lymph node basin. Primary tumours with a depth of invasion greater than 8mm have metastatic rate of 56%. Tumours with a depth of invasion between 2-8mm and evidence of cartilage destruction, lymphovascular invasion or a non-cohesive invasive front have 24% metastatic rate. Tumours outwith these high-risk groups did not metastasise.

Conclusions
Elective lymph node dissections of the superficial parotid gland, post-auricular/mastoid and level II nodes should be considered in patients with primary auricular squamous cell carcinomas with a depth of invasion >8mm or a depth of invasion between 2 - 8 mm and evidence of cartilage destruction, lymphatic invasion or a non-cohesive invasive front. This should ideally be done as part of an observational study to evaluate the cost / benefit ratio for these patients.
The neck dissection must clear the mastoid bone to a sub-periosteal level on its anterior and lateral surfaces. This will require the removal of the upper portion of sternocleidomastoid.
Sentinel lymph node biopsy requires further study to evaluate it as a method for early detection of metastatic spread in auricular squamous cell carcinoma. This could be done as part of an observational study of elective neck dissections.

• Item Type: Thesis (MD)
• Qualification Level: Doctoral
• Keywords: squamous cell carcinoma, external ear, skin cancer, lymph node metastases, neck dissection, skin cancer, sentinel lymph node biopsy, cadaveric study, lymphatic drainage, systematic review, lymphadenectomy
• Subjects: R Medicine > RB Pathology; R Medicine > RL Dermatology; R Medicine > RD Surgery
• Colleges/Schools: College of Medical Veterinary and Life Sciences > School of Cancer Sciences
• Supervisor's Name: Cooke, Prof. Tim
• Date of Award: 2009
• Depositing User: Mister Richard R Clark
• Unique ID: glathesis:2009-547
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 26 Jan 2009
• Last Modified: 10 Dec 2012 13:19
• URI: https://theses.gla.ac.uk/id/eprint/547