Primary Large Cell Neuroendocrine Carcinoma of the Parotid Gland. Report of a Rare Case

Abstract

Primary neuroendocrine carcinomas of the salivary glands are very rare neoplasms that present light microscopic, ultrastructural, and immunohistochemical features of neuroendocrine differentiation. Twelve cases have been published in the English language literature. We describe the pathologic features of a case of primary large cell neuroendocrine carcinoma of the parotid gland in a 91-year old male and summarize the immunophenotype of previously reported LCNECs of the major salivary glands. It is concluded that primary LCNEC of the salivary glands presents as a high-grade undifferentiated carcinoma, whose diagnosis may be hindered by its rarity and non-specific light microscopic features. A high level of awareness, immunohistochemical staining for neuroendocrine markers synaptophysin and CD56, and a thorough diagnostic work-up in order to exclude metastasis from a primary neuroendocrine carcinoma will allow its diagnosis.

Keywords: Carcinoma; Large cell; Neuroendocrine; Parotid neoplasms; Salivary gland diseases.

Fig. 1

Mass in the left preauricular area

Fig. 2

CT imaging. a Axial and b coronal view shows an extensive mass completely infiltrating the parotid gland and encroaching on the surrounding soft tissues (arrows)

Fig. 3

Microscopic features. a Sheets and lobules of neoplastic cells arranged in an organoid pattern. b The tumor cells have a moderate amount of eosinophilic, granular cytoplasm, large round to oval nuclei with stippled chromatin and conspicuous nucleoli. c Peripheral palisading (arrows) and rosette-like structures (asterisks). d Extensive comedo-like necrosis. (E) Basophilic incrustation of blood vessels’ wall with nuclear material (Azzopardi effect) (hematoxylin and eosin stain, original magnifications A: × 100, B, C: × 400, D: × 200, E: × 100)

Fig. 4

Τhe tumor cells are positive for a synaptophysin and b CD56 (avidin–biotin-peroxidase, original magnification × 100)