Salivary Gland Anlage Tumor Dr. Nina Gale

Clinical History A 2-week old newborn was found to have a pedunculated mass 1.4x1x1.5 cm in size, attached to the posterior nasopharyngeal mucosa. The leading presenting symptom was progressive respiratory distress. Grossly, the tumor was lobulated on the surface, firm in consistency, and whitish pink in color. Slide 1 Click to view with ImageScope Click to view with a Web-Based Viewer Slide 2 Click to view with ImageScope Click to view with a Web-Based Viewer Diagnosis: Salivary gland anlage tumor Background Salivary gland anlage tumor (SGAT) appears as a polypoid nasopharyngeal mass in newborns and infants. It is defined as a benign lesi on with mixed epithelial and mesenhimal elements, recapitulating the early stages in the embryology of the salivary gland between the 4th and 8th weeks of development [1].Dehner and co-workers introduced SGAT as a pathologic entity in 1994 [2]. The authors reported 9 cases with respiratory difficulties in the neonatal period due to nasal airway obstruction and all newborns presented a nasopharyngeal le sion with similar histologic features. One can argue whether SGAT is a true neoplasm or hamartoma. Structural si milarities and resemblance to immature salivary gland tissue, as well its obligatory midline location are con sidered indicative findings favoring SGAT as a hamartoma [2, 3]. The first description of this entity was actually published as »congenital pleomorphic adenoma« by Har-El and co-workers in 1985 [4]. Altogether, fewer than 25 cases have been reported in the literature [5]. Clinical Features A large majority of patients have been diagnosed within the first 2 weeks of life or by the age of 6 weeks. Males outnumber females by a 13:3 ratio [1]. SGAT causes symptoms of nasal obstruction, which are similar to nasal obstruction from other causes and include sleeping difficulties, feeding problems, episodes of respiratory distress and/or cyanosis, and nasal discharge [6]. Pathology Grossly, SGAT appears as a firm, polypoid frequently pedunculated, smooth or nodular, midline nasopharyngeal mass, measuring up to 3 cm in diameter. It is attached to the posterior nasopharyngeal mucosa or to the mucosa of the posterior nasal septum. The surface is usually glistening. A dim nodularity is often observed on its grayish-tan to reddish cut surface. Cysts and hemorrhages have been also detected [1]. In one case, numerous foci of necroses were evident [7]. The histologic appearance is characteristic. With its epithelial and mesechymal components, the SGAT is designated as a biphasic lesion. Microscopically, SGAT is covered by a non-keratinizing squamous epithelium. A distinct nodular pattern is found to be its recognizable finding. The nodules are separated by fibrous and myxoid stoma containing solid and duct-like cords and/or cysts of squamous epithelium deriving from the surface epithelium. These epithelial elements blend into the stromal-type nodules, which are composed of densely packed spindle to ovoid shaped cells with indistinct cell borders, eosinophilic cytoplasm and bland looking nuclei, forming short fascicles or trabecular structures, interspersed with abortive tubules. Herrmann et al. did not report cellular atypias or increased mitotic activity in the spindle cells of stromal-type nodules. In contrast, we found numerous mitoses in these cells, for example 14 mitoses per 10 high power fields. Immunohistochemical Findings Immunohistochemically, perinodal epithelial structures of squamous or ductal appearance are consistently positive for cytokeratin and epithelial membrane protein , while the nodular cells are strongly positive for cytokeratin, vimentin, smooth muscle actin, as well as for S-100 protein in scattered individual cells. All groups of cells are generally positive for salivary gland amylase. Both immunohistochemical and electron microscopical profiles confirm the structural and phenotypical complexity of the stromal nodules, which consist of an admixture of epithelial and myoepithelial cells, some of them with purely epithelial or even exceptionally with only myoepithelial components [1, 2, 8]. Differential Diagnosis The histologic differential diagnosis includes primarily biphasic synovial sarcoma, although this rarely appears in newborns. The budding of the squamous epithelium, originating from the surface in SGAT and its absence in synovial sarcoma is considered an important difference between these two entities. In addition, SGAT does not show a distinctive fasciculated fibrosarcoma-like pattern or a prominent mast-cell infiltration, present in most synovial sarcomas. Low-grade mucoepidermoid carcinoma is an additional possibility; it can be distinguished by the presence of spindle stromal cells, which are not seen in mucoepidermoid carcinoma. A remote differential diagnosis includes also a congenital teratoma. However, unlike SGAT, most teratomas of the head and neck region, including nasopharyngeal ones, are composed of mature and immature elements of neuroepithelium, cartilage and enteric or respiratory-type mucosal cysts. [2]. Treatment and Prognosis The treatment is simple surgical excision. There have been no reports of recurrences in any of the previously published cases with clinical follow up dating from 6 months to 6 years [5, 6]. References Luna MA, Cardesa A, Barnes L, Tse LLY, Hunt JL, Wenig BM, Dehner LP, Bucino JJ. In: Barnes L, Eveson JW, Reichert P, Sidransky D, eds. Pathology and genetics of head and neck tumours. World Health Organization Classifications of tumours. Lyon, IARC Press 2005: 101. Dehner LP, Valbuena L, Perez-Atayde A, Reddick RL, Askin FB, Rosai J.Salivary gland anlage tumor ("congenital pleomorphic adenoma"). A clinicopathologic, immunohistochemical and ultrastructural study of nine cases. Am J Surg Pathol. 1994;18: 25-36. Peel RL. Disease of the salivary glands. Salivary gland anlage tumor. In Barnes L ed. Surgical pathology of the head and neck. New York, Marcel Dekker, Inc. 2001: 688-690. Har-El G, Zirkin HY, Tovi F, Sidi J.Congenital pleomorphic adenoma of the nasopharynx (report of a case). J Laryngo Otol 1985; 99:1281-1287. Herrmann BW, Dehner LP, Lieu JE. Congenital salivary gland anlage tumor: a case series and review of the literature. Int J Pediatr Otorhinolaryngol. 2005; 69: 149-156. Cohen EG, Yoder M, Thomas RM, Salerno D, Isaacson G. Congenital salivary gland anlage tumor of the nasopharynx. Pediatrics 2003;112: e66-e69. Michal M, Sokol L, Mukensnabl P.Salivary gland anlage tumor. A case with widespread necrosis and large cyst formation. Pathology 1996; 28: 128-130. Pilch BZ. The nasopharynx and Waldeyer's ring. Benign neoplasms. In Pilch BZ ed. Head and neck surgical pathology. Philadelphia, Lippincott Williams&Wilkins 2001:166-170.