Diagnostic proposé:

Carcinome indifférencié de type lympho-épithéliome.

Arguments

Dans le texte de la réference ci-dessous (en gras)

Lymphoepithelial carcinoma (Oral cavity and oropharynx)

W.Y.W. Tsang, J.K.C. Chan, W. Westra

Pathology and Genetics of Head and Neck Tumours (WHO, IARCPress Lyon, 2005)

Definition
Lymphoepithelial carcinoma (LEC) is a poorly differentiated squamous cell carcinoma (SCC) or undifferentiated carcinoma, accompanied by a prominent reactive lymphoplasmacytic infiltrate. The morphological features are indistinguishable from those examples of nasopharyngeal nonkeratinizing carcinoma with a rich lymphoplasmacytic infiltrate.

Epidemiology
LEC is rare at these sites, and accounts for 0.8-2% of all oral or oropharyngeal cancers.

Etiology
Epstein-Barr virus (EBV) has been tested in only a limited number of cases, but it appears that tumours occurring in Chinese are usually positive for EBV, while those occurring in Caucasians are usually negative. The racial difference in the association with EBV is similar to LEC occurring in the major salivary glands.

Clinical features
The patients present with an intra-oral mass, which may be ulcerated. Some tumours can be bilateral. A proportion of patients present with neck mass due to regional lymph node involvement.

Location and metastatic spread
More than 90% of all oral and oropharyngeal LEC occur in the tonsil and tongue base areas. The remaining cases are found in the palate and buccal mucosa. The tumour has a high propensity for regional cervical lymph node involvement (approximately 70% of cases at presentation). Distant metastasis tends to occur in the liver and lung.

Histopathology
LEC of the oral cavity and oropharynx shows morphologic features indistinguishable from its nasopharyngeal and sinonasal counterparts. The surface epithelium is often intact. The tumour is invasive, and comprises syncytial sheets and clusters of carcinoma cells with vesicular nuclei, prominent nucleoli and ill-defined cell borders. A rich lymphoplasmacytic infiltrate is present within the tumour islands and the surronding stroma, which may appear desmoplastic. The tumour cells are immunoreactive for pan-cytokeratin and epithelial membrane antigen. EBV encoded RNA (EBER) has been demonstrated by in-situ hybridization in oral / oropharyngeal LEC occurring in Chinese patients.

Prognosis and predictive factors
LEC of the oral cavity and oropharynx are radiosensitive, and in a high percentage of cases local control can be achieved even in the presence of regional lymph node metastasis. Local, regional and distant failures occur in 3%, 5% and 19% of cases respectively. Distant metastasis is associated with a poor prognosis.

A case of lymphoepithelioma-like carcinoma arising from the palatine tonsil.

Tohoku J Exp Med. 2002 Oct;198(2):133-40.

Hidaka H, Nakamura N, Asano S, Yokoyama J, Yoshida N, Toshima M.

Department of Otorhinolaryngology, Iwaki Kyoritsu General Hospital, Iwaki 973-8555, Japan. ZAY00015@nifty.com

Lymphoepithelioma is the designation that has been given to describe undifferentiated squamous cell carcinoma variants of nasopharyngeal neoplasms (World Health Organization type 3), and a strong association with Epstein-Barr virus (EBV) infection has been established. Outside the nasopharynx, lymphoepithelioma-like carcinomas (LEC) are exceedingly rare in other head and neck lesions. This report features a rare case of LEC of the palatine tonsil occurring in a 60-year-old Japanese man who presented with a three-month history of a neck mass. The surface of tonsils were smooth, not ulcerated macroscopically, and the ipsilateral tonsil showed only slight enlargement on radiological findings. Diagnosis of lymphoepithelioma was finally made based on the pathological review of the tonsillectomy specimens, preceded by a cervical lymph node biopsy. The patient was treated with irradiation and adjuvant chemotherapy. RNA in situ hybridization as well as polymerase chain reaction (PCR) techniques, and serological testing did not demonstrate an association with EBV infection. The clinical presentation, pathological features and association with EBV are described with a review of the literature.

Lymphoepithelioma of the oropharynx.

Otolaryngol Head Neck Surg. 1989 Apr;100(4):303-7

Bansberg SF, Olsen KD, Gaffey TA.

Department of Otorhinolaryngology, Mayo Clinic, Rochester, MN 55905.

Lymphoepithelioma is common in the nasopharynx, but its presence elsewhere in Waldeyer's ring is rare. Thirteen patients with lymphoepithelioma in the tonsil and base of the tongue have been treated at our institution. At initial examination, all 13 patients had advanced clinical disease. Five years after their initial treatment, seven patients were alive and free of disease. Radiation therapy controlled local and regional disease in 10 (77%) patients, yet three of these died of distant metastasis. Patients with lymphoepithelioma have a significantly better prognosis (p less than 0.05) than do patients with either nonkeratinizing or keratinizing high-grade oropharyngeal carcinoma. Early recognition and combined therapy may further improve the prognosis. Differentiation of lymphoepithelioma from other high-grade squamous cell carcinomas of the oropharynx is important to guide treatment and to provide prognostic information.