Primary neuroendocrine small cell carcinoma of the parotid gland: A case report and review of the literature

Clinicopathological Characteristics and Survival of Small Cell Carcinoma of the Salivary Gland: a Population-Based Study

Background

Small cell carcinoma (SmCC) of the salivary gland is rare, and the characteristics and survival are not well defined due to only case reports or case series being reported. The present study aimed to describe the clinicopathological characteristics and determine the factors associated with survival of this rare cancer.

Materials and methods

A population-based study was carried out to investigate clinical characteristics and prognosis of SmCC of the salivary gland using prospectively extracted data from the Surveillance, Epidemiology and End Results (SEER) database between 1988 and 2016.

Results

Totally, 198 patients with SmCC of the salivary gland were identified with an average age of 72.6±12.4 and a male to female ratio of 3.4:1. The lesions of most patients (167/198) were located in the parotid gland. The median overall survival (mOS) of all patients is 25.0 months. The 1-, 3-, 5- and 10-year survival rate was 65.7%, 40.9%, 33.0% and 22.7%, respectively. Surgery could prolong significantly the mOS by almost 17.0 months (28.0 months vs 11.0 months; P<0.01). Radiotherapy, as well as radiotherapy after surgery, could prolong the mOS (P<0.01 for both). Patients who received chemotherapy had significantly longer overall survival time than those without chemotherapy (28.0 months vs 20 months; P=0.04). The survival analysis demonstrated that old age (>72 years), lymph node (N3) and distant metastases were independent factors for poor survival, whereas radiotherapy was an independent factor for favorable survival.

Conclusion

Small cell carcinoma of the salivary gland is a rare disease, and old age, lymph node and distant metastases, and radiotherapy were significantly associated with prognosis. In order to understand this disease more thoroughly, more cases with adequate information are required.

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.

An Extremely Rare Case of Small Cell Carcinoma in Submandibular Salivary Gland

Small Cell Carcinoma (SCC) of the salivary gland is a rare and aggressive tumour accounting for about less than 1% of the salivary gland tumours. Submandibular gland involvement is extremely rare. These tumours frequently present with metastasis to lymph node and distant organs. We report a case of a 30-year-old male patient who presented with a swelling on the left side of the face below the jaw and the floor of the mouth. The tumour was excised followed by histopathological evaluation and diagnosed as SCC of left submandibular gland. Immunohistochemistry was positive for pan cytokeratin, synaptophysin, chromogranin, Ki-67, CK5/6, and negative for Thyroid Transcription Factor (TTF-1) which confirmed that the tumour was SCC of submandibular salivary gland.

Predictors of survival in parotid small cell carcinoma: A study of 344 cases

OBJECTIVES/HYPOTHESIS

We sought to better characterize patient, tumor, and long-term survival characteristics of parotid small cell carcinoma (SmCC) with the National Cancer Database (NCDB).

STUDY DESIGN

Retrospective database review.

METHODS

We reviewed the NCDB (1998-2012) for all cases of parotid SmCC. Relevant demographic, tumor, and survival variables were extracted and analyzed. Cox multivariate regression was performed to identify prognosticators.

RESULTS

Out of 30,813 parotid gland cancers in the NCDB, we found 344 cases of parotid SmCC (1.11%). Age at diagnosis ranged from 23 to 91 years (mean = 73 years). Most patients (73.0%) were male. Most tumors were 2 to 4 cm in size (51.4%). Regional metastases were common (50.8% cN+ and 65.1% pN+) and distant metastasis (7.3%) was uncommon. Occult nodes were found in 14.4% of cases. Overall survival at 5 and 10 years was 37% and 20%, respectively. Although numerous variables were found to significantly impact survival on univariate regression analysis, age (hazard ratio [HR]: 1.05, 95% confidence interval [CI]: 1.03-1.08, P < .001), tumor size of 2 to 4 cm (HR: 2.51, 95% CI: 1.83-5.11, P = .011), tumors >4 cm (HR: 3.44, 95% CI: 1.63-7.27) and distant metastasis (HR: 2.06, 95% CI: 1.02-4.14, P = .043) remained significant prognosticators in our multivariate model. Nodal disease was not a significant risk factor after adjustment (P = .055).

CONCLUSIONS

SmCC is a rare parotid malignancy with a poor prognosis. Regional metastases were common, whereas distant metastases were uncommon. Elective neck treatment should be considered due to the incidence of occult nodal disease.

LEVEL OF EVIDENCE

4 Laryngoscope, 126:2036-2040, 2016.