A 13-year-old girl presented to the emergency department complaining of a transient loss of vision in her right eye and dizziness. She had experienced a slowly progressive right-sided nasal obstruction and proptosis during the past 3 months. On physical examination, she was noted to have a mildly proptotic right eye with normal visual performance and an unremarkable fundus.
A computed tomographic scan of her brain and sinuses was performed, which showed an expansile, well-defined mass in the right ethmoid sinus. The mass eroded the anterior skull base and extended to the orbit, exhibiting a mild mass effect on the medial rectus muscle (Figure 1).
She was then taken to the operating room, where she underwent a transnasal endoscopic biopsy of the mass in her ethmoid sinus. Several months later, she underwent an elective craniofacial resection of the tumor via a frontal craniotomy and transantral approach. Her postoperative course was uneventful, and she was discharged to home with resolution of her proptosis. She did not experience any loss in vision or cerebrospinal fluid leaking.
The right nasal and maxillary sinus mass biopsy and resection were submitted in multiple fragments, which appeared as crunchy tan-brown soft tissue that measured 1.0 × 1.0 × 0.1 cm in aggregate. Microscopically, the lesion was composed of numerous small, round ossicles resembling psammoma bodies embedded in collagenous cellular stroma with uniform, stellate, and spindle-shaped cells (Figure 2). The periphery of the lesion showed thickened trabeculae with prominent cement lines suggestive of Paget disease.
What is your diagnosis?
Pathologic Diagnosis: Psammomatoid Ossifying Fibroma
Psammomatoid ossifying fibroma was initially described by Gogl1 in 1949 as psammomatoid fibroma of the nose and paranasal sinuses. In 1985, Margo et al2 described psammomatoid ossifying fibroma as a distinctive solitary fibro-osseous lesion of young persons that affects the orbit and shows characteristic histologic features. Psammomatoid ossifying fibroma has also been reported under the designations “psammous desmo-osteoblastoma” by Makek,3 “juvenile active ossifying fibroma” by Johnson et al,4 and “juvenile ossifying fibroma” with psammoma-like ossicles by Slootweg et al.5
The lesion usually occurs in children and adolescents, although it can be seen in adults. Therefore, use of the term “juvenile ossifying fibroma” has been discouraged.2
Psammomatoid ossifying fibroma is a lesion of the extragnathic craniofacial bones, particularly the periorbital, frontal, and ethmoid bones. It is a slowly progressive lesion with a tendency toward locally aggressive behavior, including invasion and destruction of surrounding tissue, bony erosion, and recurrence after surgical excision.
Clinically, psammomatoid ossifying fibroma presents with proptosis, visual disturbances, blindness, ptosis, disturbances in ocular mobility, papilledema, recurrent headaches, and nasal obstruction. Radiographic examination reveals an expansile well-circumscribed radiolucent or mixed radiolucent/radiopaque lesion surrounded by a thick bony wall.6
The most characteristic histologic feature of psammomatoid ossifying fibroma is the presence of numerous small, round ossicles or “psammomatoid” bodies that are embedded in a cellular fibrous stroma. The ossicles are mineralized collagenous foci that vary from small, smoothly contoured round-to-oval patterns to larger, irregularly shaped ossicle-like patterns, with concentric layering similar to that of psammoma bodies. The ossicles are identified within the bony trabeculae as well as within the adjacent cellular stroma. A prominent marginal osteoid rim surrounds the ossicles. The number of ossicles varies from only a few to a dense population of innumerable spherical bodies. The ossicles rarely show included osteocytes. The stroma varies from loose and fibroblastic to intensely cellular without intervening collagen. The cellular stroma consists of round, polyhedral-to-spindle cells with a prominent basophilic nucleus and unapparent cytoplasmic borders. Rare mitotic figures without atypia are seen. Cellular pleomorphism may be evident, but it appears without anaplasia or necrosis. A basophilic myxomatous stroma with cystic degeneration can been identified focally. Giant cells can be seen among the psammomatoid ossicles or scattered throughout the nonosseous stroma.
Because psammomatoid ossifying fibroma acts as a neoplasm, the treatment of choice is complete surgical excision.7 Multiple recurrences over a long period have been reported.2,8
It is important to distinguish psammomatoid ossifying fibroma from central cementifying fibroma (ossifying fibroma, cementifying fibroma, cemento-ossifying fibroma8), which is a benign jaw lesion of odontogenic origin arising in the molar and premolar regions of the maxilla and, most commonly, the mandible. Patients with central cementifying fibroma are in the third or fourth decade of life with a distinctly female predilection. The main presenting symptom is painless swelling of the involved bone. Radiographically, central cementifying fibroma is a well-marginated, unilocular, radiolucent or variably opacified lesion. Microscopically, central cementifying fibromas consist of fibrous stroma with dense cellularity and small, spherical calcifications—“cementicles” (osseous tissue related to dental cementum). Unlike psammomatoid ossifying fibromas, central cementifying fibromas rarely recur after removal.