Sialoblastoma of the submandibular gland: a distinct entity?

Sialoblastoma is a rare congenital malignant tumor of the salivary glands. A case of a submandibular sialoblastoma in a 1.5-year-old child is presented. A comparative analysis on 79 pediatric cases reported in the literature suggests a less aggressive behavior for submandibular sialoblastoma in comparison with other sites. Classically, diagnosis is confirmed by open biopsy, but fine-needle aspiration may offer an alternative with reduced morbidity. Expression of AFP and high levels of Ki-67 have been associated with poor prognosis. Whilst early surgical resection with negative margins is widely accepted as first-line treatment, there is no consensus on therapy of recurrence and follow-up. MRI and sonography represent valid tools for the follow-up, which is usually restricted to 3-5 years.Conclusion: Submandibular sialoblastomas may have a different biological profile in comparison with parotid tumors with the absence of metastasis and much lower rate of recurrence. Comprehensive diagnostics should include additional options such as fine-needle aspiration and markers to assess cell proliferation and AFP. Literature suggests that surgery alone is sufficient for the treatment of tumors with low malignancy. Follow-up should be tailored according to the tumor site and might be limited to 3-5 years. What is Known: • Sialoblastoma is a rare congenital malignant tumor with an unpredictable clinical outcome. What is New: • Sialoblastoma of submandibular origin seems to have a less aggressive behavior in comparison with other sites. • Fine-needle aspiration and markers to assess proliferation index (i.e., suggestive of potential more aggressive course/malignancy) should be strongly considered in the diagnostic work-up. • Radical surgery as first-line therapy and a 3-5-year follow-up are acceptable for tumors with a low malignancy.

Sialoblastoma: a clinicopathologic and immunohistochemical study of 7 cases.

Sialoblastoma is a rare congenital or perinatal salivary tumor that varies in histologic features and biologic potential. Seven cases from the files of the Armed Forces Institute of Pathology are presented. These tumors occurred in 4 males and 3 females with ages ranging from prenatal to 6 months at the time of discovery. Five lesions originated from the parotid gland; 2 lesions were from the submandibular gland. All lesions presented as nodular to multinodular swellings and ranged in size from 2.0 to 7.0 cm. The principal sign or symptom was rapid growth. Two histologic patterns with differing behavior predominated: (1) a favorable pattern had semiencapsulation of cytologically benign basaloid tumor cells with intervening stroma; and (2) an unfavorable histology of anaplastic basaloid tumor cells, minimal stroma, and broad pushing to infiltrative periphery. Four and three tumors had favorable and unfavorable growth patterns, respectively. One unfavorable lesion had vascular invasion, and another demonstrated perineural invasion. All 3 tumors with unfavorable histology recurred. Tumor cells in 3 cases were immunohistochemically reactive for keratin, S-100, smooth muscle actin, and calponin to varying degrees. All 3 tumors were reactive for p63. alpha-Fetoprotein was expressed in 2 unfavorable tumors. Ki67 was expressed at 3% in a favorable tumor and 40% and 80% in the 2 unfavorable lesions. Treatment involved surgical excision. One patient received adjuvant chemotherapy. Two sialoblastomas resulted in recurrences within a year and another developed a recurrence after 4 years. One sialoblastoma developed lung metastasis within 1 month of the original biopsy. Although a clinical correlation is suggested by a favorable/unfavorable histologic grading system the biologic behavior is nonetheless considered unpredictable.

Sialoblastoma: a rare submandibular gland neoplasm.

A sialoblastoma is a rare congenital epithelial tumor that arises in a major salivary gland. To our knowledge, only 24 cases of sialoblastoma have been previously reported in the English-language literature. We report a new case, that of a 15-month-old boy who presented with a submandibular mass. Surgical excision of the mass was undertaken. Intraoperatively, the mass appeared to be adjacent to the submandibular gland, but it had not invaded it. The mass was excised, and the submandibular gland was left in place. Pathology identified the tumor as a sialoblastoma. However, pathology also revealed that residual tumor was present at the surgical margin. The patient was returned to the operating room for excision of the left submandibular gland and the level I lymph nodes. Following revision surgery, the surgical margins were negative. The patient remained disease-free at the 1-year follow-up. Despite the need for revision surgery, this case provides support for the idea that surgery alone is sufficient for curative treatment.

The congenital basal cell adenoma of salivary glands. Contribution to the differential diagnosis of congenital salivary gland tumours.

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.

Choristoma of the submandibular gland: a rare cause of cervical swelling.

A case of choristoma of the submandibular gland excised from a 4-week-old female infant is reported. The differential diagnosis is discussed and suggestions are made for the possible etiology of the lesion.

Congenital tumours of the salivary gland: a case report and review.

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.