Malignant ossifying fibromyxoid tumor of the tongue: case report and review of the literature

Abstract

Ossifying fibromyxoid tumor (OFMT) is a rare mesenchymal neoplasm that arises in subcutaneous tissue, with that in the oral cavity extremely rare. We present a case of malignant OFMT in the tongue. A 26-year-old male noticed a painless mass in the tongue, which was extracted at a general hospital. Four years later, the tumor recurred and was resected at our department. Histologically, the recurrent tumor was composed of the closely packed cells positive for vimentin and S-100 proliferating in a nodular fashion. It showed high cellularity and mitotic activity. In the primary tumor, some tumor cells were arranged in a diffuse or cord-like manner within an abundant fibromyxoid matrix, along with a small amount of metaplastic ossification, corresponding with the histopathological characteristic of OFMT. Accordingly, a diagnosis of malignant OFMT arising in typical OFMT was established. This is the first reported case of malignant OFMT in the tongue. Long-term follow-up is needed for confirmation of prognosis and biological behavior.

Figure 1

Findings of the mass in the tongue. A: Progressive swelling mass was founded at the tongue. B: Ultrasonographic findings showing a soft tissue mass. C: The cut section surface of the tumor was gray- white, solid, and firm in consistency.

Figure 2

Histopathological features of the recurrent tumor. A: Multinodular growth pattern without encapsulationis shown. (20x, Hematoxilin-Eosin staining) B: The tumor was composed of solid proliferating uniform short spindle or ovoid cells with vesicular nuclei, and a small amount of cytoplasm (100x, Hematoxilin-Eosin staining). C: The tumors cells were separated by alcian blue positive mucoid material in small areas. (200x, Alcian blue staining).

Figure 3

Immunohistochemical characteristics and proliferative activity of the recurrent tumor. A: Most tumor cells displayed immunoreactivity for vimentin (40x, Immunohistochemical staining). B: S-100 protein was also expressed in some tumor cells (40x, Immunohistochemical staining). C: Mitotic figures were easily found (400x, Hematoxilin-Eosin staining). D: Ki-67 positive cells were frequently observed (100x, Immunohistochemical staining).

Figure 4

Histopathological features of the primary tumor. A: Small amounts of metaplastic ossification and osteoid formation were found in the primary tumor (40x, Hematoxilin-Eosin staining). B: Cords of tumor cells were seen suspended within a fibromyxoid matrix (100x, Hematoxilin -Eosin staining).