SATB2 Immunoexpression in Peripheral Ossifying Fibroma and Peripheral Odontogenic Fibroma.

Peripheral ossifying fibromas (POFs) and peripheral odontogenic fibromas (POdFs) appear clinically similar but of different histogenesis. The novel marker SATB2 is involved in regulation of osteoblastic differentiation and phenotype. However, SATB2 expression has not been previously explored in POFs and POdFs. Given the potential for mineralized tissue formation in POFs and POdFs, and to more clarify the phenotype of the lesional cells, this study was aimed to immunohistochemically investigate SATB2 expression in POFs and POdFs. Fourteen cases of POF and POdF (7 cases each) were selected, stained for SATB2 immunohistochemically, and scored according to the percentage of positive lesional cells (0, no staining; 1 +, < 5%; 2 +, 5-25%; 3 +, 26-50%; 4 +, 51-75%; and 5 +, 76-100%), and the intensity of staining was graded as weak, moderate, or strong. The control group included the inflammatory fibrous hyperplasia-like area present in two cases, 1 case fibroma, and 1 case giant cell fibroma. Moderate to strong, and diffuse SATB2 nuclear immunoreactivity was detected in the lesional cells of all cases of POFs and POdFs with variable scores; 3-5 + for the POFs and 3-4 + for the POdFs (P = 0.101). The distribution of staining was more prominent in those lesional cells associated with the osteoid/calcification in the cases of POFs. No staining was noted in the control group. The lesional cells in both POFs and POdFs express SATB2 and may exhibit the osteoblastic-like phenotype. SATB2 staining may be useful for diagnosis of subsets of POFs with minimal or absent calcification and some POdFs with unidentifiable odontogenic epithelium.