Primary neuroendocrine carcinoma of the parotid gland: a case report

Proceedings of the NASHNP Companion Meeting, March 18th, 2018, Vancouver, BC, Canada: Salivary Neuroendocrine Carcinoma-An Overview of a Rare Disease with an Emphasis on Determining Tumor Origin

Salivary neuroendocrine carcinomas are rare and the overwhelming majority is high-grade. The parotid gland is the most commonly involved site followed by the submandibular gland. Most arise de novo but rare examples occurring as a high-grade transformation of another type of salivary gland neoplasm exist. There is significant morphologic and immunophenotypic overlap with neuroendocrine carcinomas of other sites, especially the skin. Like cutaneous neuroendocrine (or Merkel cell) carcinomas, approximately three-fourths are cytokeratin 20 positive. Cytokeratin 20 positive salivary neuroendocrine carcinomas are often referred to as being of the 'Merkel cell type' since most other non-cutaneous neuroendocrine carcinomas are cytokeratin 20 negative. Salivary neuroendocrine carcinomas may be challenging to separate from Merkel cell carcinomas of the head and neck on pathologic grounds because the latter often metastasize to the parotid gland. Clinical history is often relied upon to separate primary salivary tumors from cutaneous metastases but may not be helpful in all cases. Here we review the clinical, pathologic and molecular features of salivary neuroendocrine carcinomas focusing on high-grade major salivary gland tumors. The difficulty in separating salivary tumors from metastatic Merkel cell carcinoma will be highlighted.

Large cell neuroendocrine carcinoma: topic review and a unique case of metastasis to the mandible

There are few reports of large cell neuroendocrine carcinoma (LCNEC) metastasis to the head and neck region, and no cases reporting LCNEC from lung metastasizing to the mandible. LCNEC is not well reported in the literature due to recent changes in the criteria for diagnosis, revised in 2004 by the world health organization, due to its propensity for rapid growth and low 5 year prognosis. We present a 61 year old female diagnosed with LCNEC of the lung in October, 2007 treated with radiation and chemotherapy. Our patient had a PET scan performed in March, 2009 revealing no sign of metastasis. In July, 2009 she was seen for suspected sialadenitis by another department and referred to our oral and maxillofacial surgery clinic. Her signs and symptoms were consistent with metastatic disease to the mandible confirmed by histologic and immunohistochemical examination which revealed an invasive poorly differentiated non-small cell carcinoma. Palliative care was offered. Our patient died 2 years after initial diagnosis of lung cancer and 3 months after initial finding of metastatic disease. The rapid growth and spread of this cancer was surprising and knowledge of this cancer should be included in a differential diagnosis of expanding mandibular jaw lesions.

Small cell carcinoma of the salivary gland: a systematic literature review and two case reports

Salivary gland small cell carcinoma is a rare neoplasm, accounting for less than 1% of salivary gland tumours. Little is known about the epidemiologic factors and treatment of this lesion. The authors report two cases and perform a systematic literature search from 1960 to 2011 for articles on salivary gland small cell carcinoma. Once the papers were reviewed, a database was generated to analyse clinical and pathological features, treatments and outcomes, and an attempt was made to identify prognostic factors. Available data were retrieved for 44 cases which fully satisfied the inclusion criteria; the median age was 64.25 years and the male:female ratio was 2.4:1. The parotid gland was the most common site (79.6%). The overall 1-, 2- and 5-year survival rates were 75.3%, 56.4% and 36.6%, respectively. According to the present review, patient age, tumour size, distant metastasis and cytokeratin-20 positive immunostaining were all significant prognostic factors in a univariate analysis. No particular treatment approach appeared to improve survival. This work reinforces knowledge about salivary gland small cell carcinoma's epidemiologic features, and identifies new prognostic markers. The optimal management of this lesion remains controversial.

[Neuroendocrine carcinoma of the parotid gland]

INTRODUCTION

Neuroendocrine carcinomas are rarely observed in the parotid gland.

CASE REPORT

A 65-year-old woman with an uneventful history was hospitalised for a tumor in the left parotid gland which had progressed for 8 months. The clinical manifestations and the radiological findings were in favour of a malignant process involving the parotid gland. Search for local and regional extension was considered to be negative. The surgical procedure was very difficult but enabled conservative resection of the tumor by total parotidectomy. Pathology results were in favour of a neuroendocrine carcinoma of the parotid gland. External radiotherapy was proposed, but interrupted by the patient after having received 40 Gy. After a 13 month follow-up, the patient was in good general condition without any sign of relapse or metastasis.

CONCLUSION

Parotid neuroendocrine carcinomas are rare but need to be individualized owing to their poor prognosis with frequent occurrence of hepatic and pulmonary metastasis.

Metastatic neuroendocrine tumors of the parotid gland

OBJECTIVES

To present 2 cases of neuroendocrine tumors of the parotid gland and to review the clinical presentation, histopathologic, and immunohistochemical findings and treatment of these rare tumors.

STUDY DESIGN

Case series.

METHODS

This study reviews 2 patients who both presented with firm masses in the parotid gland diagnosed as neuroendocrine carcinoma by histopathologic and immunohistochemical examination. The evaluation, diagnosis, and treatment are discussed.

RESULTS

Both patients underwent complete tumor extirpation via a total or subtotal parotidectomy. Both patients received postoperative radiation therapy and chemotherapy.

CONCLUSIONS

Neuroendocrine tumors of the parotid gland are uncommon lesions; however, they have a favorable prognosis as compared to their pulmonary counterparts with early diagnosis and aggressive treatment. Diagnosis is based on the immunohistochemical characteristics of the tumor. Appropriate treatment includes complete surgical excision with postoperative radiation therapy to the parotid bed with the addition of postoperative chemotherapy in patients suspected to have metastatic disease.