Low-grade myofibroblastic sarcoma of the palate

Abstract

Low-grade myofibroblastic sarcoma (LGMS) is a rare, malignant tumor with myofibroblastic differentiation. Despite it being classified as a distinct entity by the World Health Organization, a few cases were reported in the oral and maxillofacial region. Here, a LGMS developed on the palate of a 73-year-old man who presented with a 1-cm tumor on the posterior border of the palate. Based on the histological and immunohistochemical features, a diagnosis of LGMS was established. The tumor was resected, and no recurrence was observed over 2 years. Although the tongue is the most preferred site for LGMS, it may occur in any region of the oral cavity.

Figure 1

Intraoral photo at the initial visit. An elastic, hard, 10 mm×10 mm mass is seen on the posterior border of the palate.

Figure 2

Histology of the tumor. The tumor cells had round-shaped or spindle nuclei, and the cytoplasm was eosinophilic. Mitotic cells were sparse, and atypical cells with large nuclei were observed. Hematoxylin and eosin staining, a: ×40; b: ×200.

Figure 3

Immunohistochemical staining of the tumor. The spindle cells were focally immunoreactive for α-SMA (a: ×200) and MIB-1 (b: ×200). α-SMA, α-smooth muscle actin.

Figure 4

Intraoral photo 2 years after removal of the tumor. There is only scar on the posterior border of the palate, and no reoccurrence was observed.