A 10-year-old boy was referred from another medical treatment facility for evaluation of a mass in the left cheek. The patient was unaware of the lesion until about 3 weeks prior to presentation, when he noticed that his left cheek was larger than his right. A computed tomographic scan at the referring facility demonstrated a maxillary mass.

The patient had no complaint of pain, visual field disturbances, dysphagia, or dyspnea. The patient's medical history was unremarkable, except for a diagnosis of attention deficit hyperactivity disorder that was treated with Ritalin. The physical examination was unremarkable, except for the maxillary enlargement.

Imaging studies demonstrated a soft tissue mass in the superior left maxilla measuring 4.5 × 3.7 × 3.4 cm with expansile remodeling of bone and focal loss of cortical bone (Figure 1). The mass invaded the left maxillary sinus, and mild migration of 1 tooth was apparent. The radiographic differential diagnosis included osteosarcoma, adamantinoma, and an atypical presentation of a benign fibrous process.

The patient was treated with a segmental resection of the left maxilla. Grossly, the lesion was a partially encapsulated mass involving the superior portion of the left maxilla and left maxillary sinus (Figure 2). Microscopically, the lesion consisted of a cellular stroma containing spindled-to-stellate cells with eosinophilic cytoplasm and indistinct cell borders in a collagenous-to-myxoid background (Figure 3; hematoxylin-eosin, original magnification ×20). Irregular foci of calcifications were identified, some of which were psammomatoid, while others were composed of immature osteoid. The nuclei were uniform with infrequent mitotic figures (Figure 4; hematoxylin-eosin, original magnification ×40).

What is your diagnosis?

The juvenile ossifying fibroma is a subtype of the ossifying fibroma, a benign neoplasm with a substantial growth potential. The lesion was first described by Benjamins in 1938.1 The addition of the descriptor “juvenile” implies characteristics such as an earlier age of onset, differing common anatomic sites, and pathologic behavior. However, some authors prefer to avoid the term juvenile, as the lesion can occur in adults.2,3 Like the ossifying fibroma, the juvenile ossifying fibroma is a central lesion of bone composed of variable amounts of fibrous tissue proliferation and foci of calcifications. Two histologic patterns are classically described: (1) trabecular and (2) psammomatoid.4 The juvenile ossifying fibroma has also been termed the juvenile active ossifying fibroma, the juvenile aggressive ossifying fibroma, and the aggressive psammomatoid ossifying fibroma. The ossifying fibroma is a member of a broader category of osseous lesions termed fibro-osseous lesions.

The age at presentation is variable and ranges from 3 months to more than 70 years.5 No significant sex predilection has been reported.6 These lesions tend to be discovered on routine radiographic examination, or patients present with facial enlargement due to cortical expansion. Other common presenting symptoms are nasal obstruction, pain, sinusitis, and proptosis. According to one study, proptosis is the most common presenting symptom, occurring in 16 of 21 cases.2 

Ossifying fibromas occur primarily in the craniofacial skeleton. Slootweg et al6 reviewed cases from the university hospitals at Groningen and Utrecht and noted 12 maxillary lesions, 20 mandibular lesions, and 2 occurrences in the paranasal sinuses. The trabecular type, termed “juvenile ossifying fibroma—WHO [World Health Organization] type” in the study, had a predilection for the maxilla.6 Margo et al3 reviewed 21 cases from the Armed Forces Institute of Pathology involving the orbit and found 10 cases involving the orbital plate of the frontal bone (supraorbital) and 9 cases centered in the ethmoid sinus. In 2 cases, the precise location was unclear. Johnson et al5 reviewed 3000 fibro-osseous lesions in the registry at the Armed Forces Institute of Pathology and found that 112 met the criteria for the juvenile active ossifying fibroma. Ninety percent of these involved the paranasal sinuses.5 Cases involving the temporal bone have also been reported.7 Additionally, reports of presentations as soft tissue masses have been noted.8 However, the common peripheral ossifying fibroma of the gingiva is not considered a soft tissue variant of the central ossifying fibroma.

Grossly, the juvenile ossifying fibroma appears as a discrete mass, well demarcated from the surrounding bone, though not encapsulated. On sectioning, the cut surface is typically a tan-white, rubbery, homogeneous mass with a firm-to-gritty consistency. Microscopically, 3 characteristics are noted: (1) mineralized “psammomatoid” bodies or ossicles; (2) cellular stroma of closely packed round-to-polyhedral to spindle-shaped cells; and (3) a myxomatous matrix.2,5 The ossicles can vary in appearance from small, round-to-oval masses with concentric layering to osteoid with encased osteocytes. Multinucleated giant cells are occasionally identified and are usually thought to be osteoclasts.

The clinical management of the juvenile ossifying fibroma is unclear. Some lesions display an indolent growth pattern, whereas others enlarge rapidly. For small lesions, curettage or simple excision is adequate. However, larger or rapidly growing lesions require a wide excision or resection. Recurrence rates from 30% to 58% have been reported.4 No cases involving malignant transformation have been reported.4 

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Author notes

Corresponding author: Lt Col David L. Wells, USAF, Department of Oral and Maxillofacial Pathology, National Naval Dental Center, Building 1, Room 4405, 8901 Wisconsin Ave, Bethesda, MD 20889 ([email protected])