Sialoblastoma of the cheek: A case report and review of the literature

Abstract

Sialoblastoma is a rare salivary gland tumor that recapitulates the primitive salivary gland anlage. The authors herein report a case of sialoblastoma of a minor salivary gland, clinically presenting with progressive enlargement of a mass in the cheek of a 1-year-old female infant. Histopathologically, the mass consisted of tight clusters of basaloid cells and partially formed ductal and pseudo-ductal spaces separated by thin fibrous bands. Immunohistchemical studies demonstrated the presence of cytokeratin AE1/AE3, p63, CD99, α-fetoprotein (AFP) and Hep Par-1 expression in a considerable number of tumor cells. The clinical and pathological characteristics are presented and relevant literature is reviewed. Early complete surgical excision is recommended for the treatment of sialoblastoma. Radiation may be considered in cases with incomplete resection of the tumor. Chemotherapy may play a vital role in extensive, metastatic, or relapsed cases, or in cases with inadequate excision. The follow-up treatment should be frequent and prolonged. To the best of our knowledge, this is the first reported case of sialoblastoma of the cheek with immunoreactivity for AFP and Hep Par-1, which may be associated with the embryonic origin of the tumor. AFP may be a useful marker of tumor response in patient with sialoblastoma.

Keywords: Hep Par-1; cheek; salivary gland tumor; sialoblastoma; α-fetoprotein.

Figure 1.

(A) Magnetic resonance imaging (MRI) axial T1-weighted (T1W) image showing a lobulated soft tissue lesion anterior to the right mandible. (B) MRI axial contrast-enhanced T1W image showing minimal enhancement.

Figure 2.

(A) Macroscopically, the excised tumor was a lobulated soft tissue mass. (B) Cut sections of the tumor showing a homogenous solid lobulated gray-tan surface.

Figure 3.

Microscopically, the tumor was composed of solid nests of basaloid cells with thin intervening stroma. The tumor cells exhibited a high nuclear:cytoplasmic ratio, round to oval nuclei, fine nuclear chromatin, small nucleoli and scant to moderate pale eosinophilic cytoplasm (hematoxylin and eosin staining; magnification, ×100).

Figure 4.

Primitive duct structures were observed on microscopic examination (magnification, ×400).

Figure 5.

The tumor cells exhibited immunoreactivity for α-fetoprotein (magnification, ×400).

Figure 6.

The tumor cells exhibited immunoreactivity for Hep Par-1 (magnification, ×400).