Sialoblastoma of the submandibular gland: a distinct entity?

Abstract

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.

Keywords: Children; Congenital tumor; Salivary gland; Sialoblastoma.