A Spontaneous Epithelial-Myoepithelial Carcinoma of the Submandibular Gland in a Sprague-Dawley Rat

Abstract

The present report describes a rare case of spontaneous tumor of the salivary gland in a male Sprague-Dawley rat. The clinically confirmed mass rapidly developed in the cervical region between 19 and 21 weeks of age, and the animal was subsequently euthanized. At necropsy, a well-circumscribed nodule approximately 7 × 6 cm in diameter was found at the site of the salivary gland. The cut surface of the nodule was lobulated and soft and had a pinkish tan fish-flesh appearance. One large cyst (approximately 3 × 2 cm in size) containing reddish fluid was also present in the nodule. Histopathologically, the tumor, with a partially lobulated structure, was surrounded by a thin fibrous capsule. The majority of tumor cells formed a diffuse solid sheet structure that mainly consisted of small ovoid or spindle-shaped cells. In the tumor periphery, some cells were arranged in nest-like structures. Small duct-like structures lined with a monolayer of cuboidal epithelial cells resembling an intercalated duct or large polygonal clear cells with a myoepithelial component were also observed. Mitotic figures and necrotic foci were frequently observed in solid areas. Immunohistochemically, the tumor cells were positive for cytokeratin, epithelial membrane antigen, vimentin, p63, α-smooth muscle actin and calponin. The cells were negative for calcitonin, synaptophysin and chromogranin A. On the basis of these findings, the tumor was diagnosed as an epithelial-myoepithelial carcinoma originating from the luminal epithelial cells and myoepithelial cells in the submandibular gland.

Poorly differentiated salivary gland carcinoma with prominent squamous metaplasia in a pregnant Wistar Hannover rat

“…The tumor cells were cuboidal to tall columnar epithelium with mucoid, pale cytoplasm and medium to large nuclei; however, myoepithelium-like tumor cells did not appear to be associated with the tumor cysts and the papillae. In contrast, the present case was closely similar to two previous cases of SD rats that exhibited poorly-differentiated tumor cells with a diffuse sheet or nest-like structure [ 8 , 11 ]. Immunohistochemically, the tumor cells in these cases tested positive for epithelial cell markers (such as keratin, AE1/3 and/or epithelial membrane antigen) and myoepithelial cell markers (such as vimentin, αSMA, GFAP and/or p63).…”

“…It is relatively rare for pathologists to find a spontaneous tumor in pregnant female rats. Such a poorly-differentiated salivary gland tumor, as reported in relatively young adult-aged rats [ 8 , 11 , 14 ], may have incidentally developed in the pregnant female Wistar rat in the current case report.…”

“…A 10-week-old male SD rat also showed a poorly differentiated carcinoma that had developed in the submandibular gland; the tumor cells tested positive for keratin and/or vimentin and possessed epithelial/mesenchymal (bipotential) cell lineages [ 11 ]. A similar case, diagnosed as epithelial-myoepithelial carcinoma, was reported in a 21-week-old male SD rat [ 8 ]. In the present case report, we describe the histological characteristics of a poorly differentiated carcinoma with a suspected salivary gland origin in a pregnant 16-week-old Wistar BrlHan: WIST@Jcl (GALAS) rat.…”

Clinical, pathological and immunohistochemical characterization of spontaneous neoplasms in pet rodents in Northeastern Brazil

“…As in domestic animals, reports of salivary gland neoplasms in rodents are rare but are usually carcinomas as reported in chinchillas (Smith et al 2010), rats (Kobayashi et al 2010, Li et al 2013, and in a free-ranging porcupine (Perles et al 2017). Oral cavity neoplasms in Syrian hamsters are infrequent, and spontaneous salivary tumors are rarely reported (Rainwater et al 2011).…”

Recurrent myoepithelial carcinoma of the submandibular gland treated by rAd-p53 combined with radiotherapy: A case report

“…The cells contact and expel the secretions of the exocrine glands, including the salivary, sweat, bartholin, prostate and lacrimal glands, the galactophores and pancreas, and the tissue originates from ectoderm and has epithelial features (7,8). Epithelial-myoepithelial carcinomas of the salivary gland can develop malignancy from benign myoepithelial carcinomas, with the exception of primary carcinomas (4,5).…”