Background

This is an extremely rare tumor that presents in then newborn period. It has an indolent behavior and complete excision is usually curative.

Outline

Epidemiology
Disease Associations
Pathogenesis
Laboratory/Radiologic/Other Diagnostic Testing
Gross Appearance and Clinical Variants
Histopathological Features and Variants
Special Stains/Immunohistochemistry/Electron Microscopy
Differential Diagnosis
Prognosis and Treatment
Commonly Used Terms

EPIDEMIOLOGY	CHARACTERIZATION
SYNONYMS	Embryoma
INCIDENCE	Rare
AGE RANGE-MEDIAN	Newborn

 

DISEASE ASSOCIATIONS	CHARACTERIZATION
HEPATOBLASTOMA
Sialoblastoma and hepatoblastoma in a neonate. Siddiqi SH, Solomon MP, Haller JO. Department of Radiology, Mount Auburn Hospital, Cambridge, MA 02238, USA.	Pediatr Radiol 2000 May;30(5):349-51 Abstract quote We report a case of salivary gland neoplasm and associated hepatoblastoma. The sialoblastoma was diagnosed by prenatal sonography; however, the hepatoblastoma was imaged post-operatively. Prior knowledge could have prevented a subsequent operation, including the additional risks of repeat anesthesia. We suggest that if a sialoblastoma is in the differential diagnosis, then additional imaging may be indicated because of the possibility of associated lesions.

 

PATHOGENESIS	CHARACTERIZATION
Neoplasm	Most agree this represents a true neoplasm

 

LABORATORY/RADIOLOGIC/ OTHER TESTS	CHARACTERIZATION
RADIOLOGIC
Sialoblastoma (embryoma): MR findings of a rare pediatric salivary gland tumor. Som PM, Brandwein M, Silvers AR, Rothschild MA. Department of Radiology, Mount Sinai School of Medicine of the City University of New York, NY 10029, USA.	AJNR Am J Neuroradiol 1997 May;18(5):847-50 Abstract quote We report the findings in a 21-month-old girl who had a noninfiltrating mass in the left cheek, just anterior to the masseter muscle, which, at surgery, proved to be a sialoblastoma. Sialoblastoma has a histologic appearance reminiscent of a primitive state of salivary gland development; that is, it shows an arrested state of salivary maturation. MR imaging in this case showed that the lesion was isointense with muscle on T1-weighted images, had a high-intermediate signal intensity similar to that of fat on T2-weighted images, and enhanced sparsely and nonhomogeneously.

 

GROSS APPEARANCE/ CLINICAL VARIANTS	CHARACTERIZATION
GENERAL
Congenital tumours of the salivary gland: a case report and review. Harris MD, McKeever P, Robertson JM. Department of Histopathology, Peterborough District Hospital, UK.	Histopathology 1990 Aug;17(2):155-7 Abstract quote A congenital epithelial tumour of the submandibular salivary gland, occurring in a child of 10 months, is described. The lesion appeared benign and consisted of basal type cells, showing ductal and acinar differentiation with myoepithelial cells. The associated fibrous stroma contained blood vessels and small nerve bundles. A few similar lesions have been reported in the past, some of which showed features of malignancy. Although various names have been proposed, we suggest that these lesions represent a single group derived from a primitive cell line and advocate the use of the term sialoblastoma.
Embryoma (sialoblastoma) of salivary glands. Batsakis JG, Frankenthaler R. Dept of Pathology, University of Texas M. D. Anderson Cancer Center, Houston 77030.	Ann Otol Rhinol Laryngol 1992 Nov;101(11):958-60 Abstract quote There are four clinicopathologic categories of the exclusively major salivary gland tumors that present in the perinatal period. The two with the smallest representation among the 20 cases reported to date are those with a hamartomalike appearance and those with benign adult equivalents--the pleomorphic and monomorphic adenomas. Five cases have been undifferentiated or basaloid salivary carcinomas. Embryomas (sialoblastomas) are the most numerous. These tumors manifest a histologic phenotype like that of the epithelial anlage of the salivary glands, albeit in an arrested state of differentiation.
VARIANTS
SUBMANDIBULAR GLAND
Sialoblastoma of the submandibular gland: report of a case and review of the literature. Mostafapour SP, Folz B, Barlow D, Manning S. Department of Otolaryngology-Head and Neck Surgery, University of Washington Medical Center, Seattle 98195, USA.	Int J Pediatr Otorhinolaryngol 2000 Jun 30;53(2):157-61 Abstract quote Sialoblastomas are rare perinatal epithelial salivary tumors, with only 22 reported cases in the literature. While they have been reported to occur predominantly in the parotid gland, we present one case of sialoblastoma of submandibular gland origin. The surgical management of this patient is discussed. Histopathologic examination, including immunochemical, ultrastructural and cytogenetic studies, was performed. Pertinent literature is reviewed.

 

HISTOLOGICAL TYPES	CHARACTERIZATION
GENERAL
Sialoblastoma: clinicopathological/immunohistochemical study. Brandwein M, Al-Naeif NS, Manwani D, Som P, Goldfeder L, Rothschild M, Granowetter L. Department of Otolaryngology, Mount Sinai School of Medicine, City University of New York, New York 10021, USA.	Am J Surg Pathol 1999 Mar;23(3):342-8 Abstract quote Sialoblastoma is an extremely rare salivary tumor diagnosed at birth or shortly thereafter with significant variability in histologic range and clinical course, so that for an individual case it may be difficult to predict the most appropriate therapy. We detail the case of a toddler noted to have a firm 1-2-cm mass in the left cheek at 21 months. Parotidectomy was performed at 26 months, revealing a sialoblastoma; the resection margins were positive. During the next 10 months, the mass recurred or persisted, necessitating numerous procedures. The tumor was composed of basaloid cells with fine chromatin and other more mature cuboidal epithelial cells. Ductules and solid organoid nests with some tendency toward peripheral pallisading were also noted. There was no perineural invasion; necrosis initially was sparse but increased over time. The mitotic rate also increased from 6 to 7/10 high-power fields in the first resection to 20/10 high-power fields in the last resection. Nuclear pleomorphism increased with time. The MiB1 proliferative index revealed a dramatic increase in the number of labeled nuclei: from 3 cells/10 high-power fields in the first specimen to 94 cells/10 high-power fields for the last specimen. Cytokeratin accentuated the ductal structures. S-100 showed a diffuse staining pattern, with darker staining of the spindled myoepithelial cells. The Her-2-neu protein showed moderate cytoplasmic staining, whereas the p53 showed only occasional labeling of nuclei. This is the first case of sialoblastoma with evidence of increasing anaplasia based on increasing proliferative capacity. Therefore, the distinction between benign and malignant sialoblastomas may not be as well defined as previously thought. The patient's prognosis is likely to be determined by the tumor grade as well as the stage at presentation and the extent of resection.

 

SPECIAL STAINS/IMMUNOPEROXIDASE/ OTHER	CHARACTERIZATION
SPECIAL STAINS
IMMUNOPEROXIDASE
Sialoblastoma: a case report and review of the literature on congenital epithelial tumors of salivary gland origin. Hsueh C, Gonzalez-Crussi F. Department of Pathology, Children's Memorial Hospital of Chicago, Illinois.	Pediatr Pathol 1992 Mar-Apr;12(2):205-14 Abstract quote The histologic, immunohistochemical, and ultrastructural features of a congenital epithelial tumor of the parotid were studied. The tumor was characterized by solid nests of epithelial cells intermingled with proliferating ductal structures lined by a double layer of cells. Immunoperoxidase staining for cytokeratin, vimentin, actin, and S-100 protein showed the presence of cytokeratin in the ductal cells as well as the presence of vimentin, actin, and S-100 protein in the outermost layer of the ducts. The solid nests were focally reactive to S-100 and vimentin. Ultrastructural examination revealed myoepithelial cells with replication of basement membrane material. The tumor recurred 17 months after excision without lymph node involvement or metastasis. The term "sialoblastoma" is favored. Review of the literature on congenital, epithelial salivary gland tumors showed that a few cases recurred locally and only one case had regional lymph node involvement. No distant metastasis has been reported.

 

DIFFERENTIAL DIAGNOSIS	KEY DIFFERENTIATING FEATURES
CONGENITAL BASAL CELL ADENOMA
The congenital basal cell adenoma of salivary glands. Contribution to the differential diagnosis of congenital salivary gland tumours. Seifert G, Donath K. Institute of Pathology, University of Hamburg, Germany.	Virchows Arch 1997 Apr;430(4):311-9 Abstract quote Congenital epithelial tumours of the salivary glands are very rare. The Salivary Gland Registry maintained in the Department of Pathology. University of Hamburg, contains only three cases among a total of 6,646 salivary gland tumours from the years 1965-1994. The three cases were classified as congenital basal cell adenoma, two of the parotid gland and one of the submandibular gland. Histologically, the three adenomas were similar in structure to the adult counterpart of basal cell adenoma with solid, trabecular or tubular (duct-like) patterns. In some cystic spaces of the duct-like structures PAS- and Astra blue-positive substances were secreted. On immunocytochemistry, the luminal duct-like cells showed membranous expression of cytokeratins 3, 5, 6, 7, 13 and 19. In the isomorphic basaloid cells of the solid and trabecular cell nests few cells expressed cytokeratin. On the outside of the solid cell nests there were smaller elongated myoepithelial-like cells, which expressed cytokeratin 14 and vimentin. Cytokeratins 1, 2, 4 and 18 were not expressed. The pattern of expression reflects the different stages of maturity of the tumour cells and is related to the development of the salivary glands until the end of the 3rd embryonal month with an arrest of further cell differentiation. No acinic cells, invasive growth, recurrence or metastases were observed. The differential diagnosis includes other congenital salivary gland tumours, such as hybrid basal cell adenoma-adenoid cystic carcinoma, sialoblastoma or embryoma, carcinoma, hamartoma and teratoma.

 

PROGNOSIS AND TREATMENT	CHARACTERIZATION
PROGNOSTIC FACTORS
Diagnostic and therapeutic approach to sialoblastoma: report of a case. Alvarez-Mendoza A, Calderon-Elvir C, Carrasco-Daza D. Department of Pathology, Instituto Nacional de Pediatria, Mexico City, DF, Mexico.	J Pediatr Surg 1999 Dec;34(12):1875-7 Abstract quote The natural history of a rare parotid tumor, the sialoblastoma (embryoma) is reported. It is a blastematous neoplasm said to recapitulate the epithelial differentiation of a gland at various stages of development. The tumor grew in a period of 5 years (from shortly after birth until it was excised) to a firm asymptomatic mass measuring 5 cm in greatest diameter. With a diagnosis of adenoid cystic carcinoma (a common misdiagnosis), the patient was referred to the reporting institution, where the diagnosis was revised. Five months later, completion parotidectomy for presumed recurrence failed to demonstrate residual tumor. One year later, the patient appears to be free of disease. The authors propose that sialoblastomas should be regarded neither as benign nor malignant, but as one single disease with local infiltrative potential. Based on this concept, sialoblastomas can be treated with early conservative surgery alone, provided that free margins are obtained.

Rosai J. Ackerman's Surgical Pathology. Eight Edition. Mosby 1996.
Sternberg S. Diagnostic Surgical Pathology. Third Edition. Lipincott Williams and Wilkins 1999.

Salivary Glands

Last Updated 1/25/2002