A 9-year-old male presented with left eye proptosis. Imaging revealed an expansile, 7 cm, well-demarcated mass centered in the posterior nasal cavity and ethmoid sinus with bone destruction, also affecting surrounding structures, including the left eye muscle, dura, and skull base. The patient underwent resection of tumor. Macroscopic examination revealed multiple tan-white pieces of lobulated tissue with firm, homogenous, gritty cut surfaces. Histologically, the mass was composed of a bland, moderately cellular spindle cell proliferation and abundant short spherical ossicles with variable mineralization.
1. Which of the following statements is incorrect for this entity?
2. What molecular alteration is commonly associated with this entity?
Psammomatoid Ossifying Fibroma
Psammomatoid Ossifying Fibroma (PsOF) is a rare, benign but aggressive fibro-osseous neoplasm. It commonly involves the craniofacial bones; mostly paranasal sinuses and less commonly jaw. It affects children and young adults, with a slight male predominance. Radiologically, it typically appears as a well-demarcated expansile mass with mixed radiopaque and radiolucent areas and frequent discrete calcifications. Cortical thinning or remodeling, bone perforation, tooth displacement and intracranial extension may be seen.
Histologically, it is characterized by hypercellular stroma of bland ovoid and spindle cells and numerous psammoma-like spherical ossicles. Ossicles may fuse together in late disease, forming lumpy trabeculae. It also may exhibit cystic degeneration and aneurysmal bone cyst formation.
It has been recently discovered that PsOF is associated with recurrent SATB2 gene rearrangement, which can be detected by fluorescent in situ hybridization and can be particularly helpful to exclude common differential diagnoses in this anatomic site.
The main differential diagnosis for PsOF includes other fibro-osseous lesions. Cemento-ossifying fibroma (COF) is one of the closest differential diagnosis by H&E morphology. However, COF almost exclusively occurs in tooth-bearing areas of the jaws, with mandible being the most common location. Fibrous dysplasia (FD) is also in the differential diagnosis, however the bony spicules in FD are in the form of curvilinear trabeculae. In addition, FD is associated with GNAS gene mutations.
Due to the aggressive nature of PsOF, total resection is the recommended treatment. Prognosis is excellent after complete excision. Recurrence can be seen in approximately 30% of cases with positive margins. No malignant transformation has been described so far.
References
- Cleven AHG, Szuhai K, van IJzendoorn DGP, Groen E, Baelde H, Schreuder WH, Briaire-de Bruijn IH, van der Meeren SW, Kleijwegt MC, Furth WR, Kroon HM, Suurmeijer AJH, Savci-Heijink DC, Baumhoer D, Bovée JVMG. Psammomatoid Ossifying Fibroma Is Defined by SATB2 Rearrangement. Mod Pathol. 2023 Jan;36(1):100013. doi: 10.1016/j.modpat.2022.100013. PMID: 36788065.
- Tabareau-Delalande F, Collin C, Gomez-Brouchet A, Bouvier C, Decouvelaere AV, de Muret A, Pagès JC, de Pinieux G. Chromosome 12 long arm rearrangement covering MDM2 and RASAL1 is associated with aggressive craniofacial juvenile ossifying fibroma and extracranial psammomatoid fibro-osseous lesions. Mod Pathol. 2015 Jan;28(1):48-56. doi: 10.1038/modpathol.2014.80. Epub 2014 Jun 13. PMID: 24925056.
Quiz Answers
Q1 = 2. Jaw is more commonly affected than paranasal sinuses and orbit.
Q2 = C. SATB2 rearrangement
