A rare case of tonsillar mucoepidermoid carcinoma

Abstract

Mucoepidermoid carcinoma (MEC) is one of the most common histological malignant salivary gland tumors, it is most frequently diagnosed in the parotid gland. MEC is also diagnosed in the intra oral minor salivary glands. Only a few cases of tonsillar MEC have been reported. We present a rare case of mucoepidermoid carcinoma arising from the left pharyngeal tonsil. This case report shows that it is important to perform tonsillectomy when discovering neck metastasis of salivary gland tumors with unknown primary.

Keywords:

• Oropharyngeal cancer
• mucoepidermoid cancer
• head and neck cancer
• salivary gland carcinoma

Background

Mucoepidermoid carcinoma (MEC) is one of the most common malignant salivary gland tumors [1–3]. Almost 75% of all patients are females.

It is also the most common malignant salivary glands tumor among children [4].

A variety of different malignant tumors can arise from the palatine tonsils, most of the cases are squamous cell carcinoma followed by lymphoproliferative diseases. Metastasis to the tonsils is rare but are usually, when present, from the lung, gastrointestinal tract, or the kidneys [5–8].

The oral cavity contains minor salivary glands distributed through the mucosa. Minor salivary gland tumors are well described in the oral cavity, but not in the pharyngeal tonsils [9].

To our knowledge there are only a scarce amount of mucoepidermoid carcinoma cases of the pharyngeal tonsils reported [10–12]. The aim of this case report is to present an unusual case of head and neck carcinoma.

Case report

A 46-year-old previous smoking male presented with a lump in the left neck at level IIa. The lump had been present for almost 2 months and had been growing. Intra oral and flexible endoscopy was normal. An ultrasound of the left neck detected a 29 × 24 × 12 millimeter necrotic node. Fine needle aspiration and core needle biopsy showed malignant cells and a high suspicion of mucoepidermoid carcinoma. A computer tomography (CT) of the neck and thorax showed contrast enhancement in the left palatine tonsil but symmetric conditions in the oropharynx regarding tonsillar size. The necrotic lymph node was the most prominent one in neck level IIa (Figure 1). CT also showed a couple enlarged lymph nodes in left level III. The case was discussed at a Multi Disciplinary Tumor Board meeting (MDTB). The treatment decision was radical tonsillectomy with left side neck dissection levels I–V. The operative pathology report showed a MEC of the left tonsil, measuring 18 × 9×5 millimeter (Figure 2). The tumor was graded according to Brandwein [13] and Armed Forces Institute of Pathology [14] and was scored 9 and 8, respectively thus being a high grade MEC. Two metastases were present in neck levels IIa and Vb. Ki-67 was estimated to 70%. The tumor was graded as pT1N3bM0 according to AJCC [15]. The case was discussed once again at MDTB and postoperative radiotherapy was decided. The patient received 68 Gray to the oropharynx and the left neck. A FDG-PET, three months after the radiotherapy, was conducted showed no pathologic uptake in the head and neck or thorax.

Figure 1. (a,b) Computer tomography showing metastasis of mucoepidermoid carcinoma in left neck level IIa.

Figure 2. (a) Histological slide showing the mucoepidermoid carcinoma in the tonsil, hotspot within circle. (b) Histological slide showing metastasis of mucoepidermoid carcinoma in lymph node, hotspot within circle.

Discussion

MEC is one of the most common malignant salivary gland tumors. It is most commonly diagnosed in the parotid gland [4,16]. The palate, buccal mucosa, tongue and gingiva are the most common minor salivary gland sites for MEC [17,18]. Only a few cases of MEC have been found in the pharyngeal tonsil [10–12].

This case report describes a case of MEC affecting the left tonsil. The pharyngeal tonsils along with the tonsil of the tongue base are lymphatic tissues that are components of the Waldeyer ring. The Waldeyer ring are believed to be a site for antibody synthesis [19,20]. Carcinoma from the tonsils is a rapid increasing disease, this is proclaimed to because of the rapid increase in HPV. HPV positive carcinoma is of squamous cell type and is the most common type of carcinoma of the tonsil [21].

Our described patient was 46 years old at diagnosis. This is in line with previous case report where the patients were 47 and 48 at diagnosis [10,11].

The patient was managed by bilateral tonsillectomy and neck dissection followed by post-operative radiotherapy, which also was the management of choice reported by Jarvis et al. [11]. Our described patient has been followed up for three months and does not show any signs of recurrence. He will undergo a new FDG-PET six months after termination of treatment.

This case report shows that mucoepidermoid cancers can arise from the pharyngeal tonsils. Thus, it is important to perform tonsillectomy for patients with metastasis of mucoepidermoid carcinomas, if prior imaging does not provide any information regarding primary tumor in the salivary glands.

Ethical approval

Written consent was obtained from the patient.

Informed consent

Authors confirm that consent was obtained from the patient for this study.

Disclosure statement

No potential conflict of interest was reported by the author(s). The authors wish to acknowledge the funding, from Linkoping University, in order to publish this case report.