Mucinous Carcinoma with Neuroendocrine Differentiation of Salivary Gland Origin

Abstract

Primary mucinous adenocarcinomas of the salivary gland are rare malignancies defined by aggregates of epithelial cells suspended in large pools of extracellular mucin. We report a case of a giant mucinous adenocarcinoma of salivary gland origin, with low-grade cytoarchitectural features and neuroendocrine differentiation arising in the submental region. Grossly, the tumor measured 12.5 × 13.4 × 8.2 cm and replaced the bone and soft tissues of the anterior oral cavity. Microscopically, the neoplasm was composed of large extracellular pools of mucin, which contained papillary and acinar aggregates, and small nodules of ductal type epithelium with minimal nuclear enlargement, powdery chromatin and little pleomorphism. The nodules comprised 20 % of the tumor and showed morphologic and immunohistochemical evidence of neuroendocrine differentiation. Examination revealed histologic features comparable to mammary gland analogues in mucin predominance, ductal type morphology, expression of estrogen and progesterone receptors, and GATA-3 positivity. This is the first case reported of mucin-rich carcinoma of salivary gland origin exhibiting neuroendocrine differentiation.

Keywords: Head and neck cancer; Mucin-rich carcinoma; Mucinous adenocarcinoma; Neuroendocrine differentiation; Reconstructive surgery; Salivary cancer; Salivary duct carcinoma.

Fig. 1

Preoperative photodocumentation. a Frontal view. b Base view. c Left oblique view. d Left lateral view

Fig. 2

Preoperative imaging. a Axial T2-weighted MRI Neck showing a T2-intense lesion involving the submentum. b Sagittal T1-weighted MRI with contrast exhibiting a T1-hypointense lesion involving the floor of mouth and ventral tongue. c Axial PET/CT demonstrating a destructive FDG-avid lesion with erosion into the anterior mandible. d Sagittal PET/CT exhibiting FDG-avid lesion adjacent to the normal tongue

Fig. 3

Intraoperative photodocumentation. a Lower lip split. b Mandibulectomy cutting guides in place. c Tumor release after mandibulectomy. d Tumor specimen prior to release at ventral tongue and floor of mouth. e En bloc specimen with negative margins

Fig. 4

Postoperative photodocumentation one month after surgery. a Frontal view. b Right oblique view. c Left oblique view. d Left lateral view

Fig. 5

Pathological staining of mucin-rich carcinoma. a Small ductal papillary structures suspended in extracellular mucin, representative of 80 % of overall tumor. b Solid areas of carcinoma attached to or emanating from mucosa. c. Solid areas of tumor attached to skin with some areas possibly representing intraepidermal spread. d. Diffuse and strong nuclear reactivity for estrogen receptor staining. e Solid tumor nodules with neuroendocrine cytologic features. f Chromogranin positivity within the solid nodules of tumor with reduced intensity in mucinous areas. g Strong nuclear reactivity for GATA-3