Mucinous adenocarcinoma is a rare malignant neoplasm characterized by large amount of extracellular epithelial mucin that contains cords, nests, and solitary epithelial cells. The incidence is unknown. Limited data indicate that most, if not all, occur in the major salivary glands with the submandibular gland as the predominant site. These tumors may be associated with dull pain and tenderness. This neoplasm may be considered to be low-grade.
Clinical Features.
Clinically, these lesions are soft, spongy masses that may be thought to be cysts.
Histologic Features.
The gross specimens are very mucoid, with a slimy texture and they may actually ooze mucoid material. These tumors are circumscribed but not encapsulated. Low magnification reveals islands and cords of tumor cells that appear to be floating within pools of pale staining mucin. The pools of mucin may be divided into irregular lobules by fibrous connective tissue septa that course through the tumor, which is unencapsulated. The tumor cells are moderately large, cuboidal, and polygonal cells with eosinophilic to amphophilic cytoplasm. The nuclei are vesicular, and scattered mitotic figures may be found. The tumor islands are surrounded by palestaining mucoid substance. The mucoid substance stains with mucicarmine, periodic acid-schiff, and alcian blue at pH 2.0. Mucicarmine stain also reveals that many tumor cells contain intracytoplasmic mucin.
Treatment and Prognosis.
Complete excision with the care to avoid seeding the surgical site would seem to be a satisfactory mode of treatment for these salivary gland tumors.