Sino-orbital osteoma: a clinicopathologic study of 45 surgically treated cases with emphasis on tumors with osteoblastoma-like features.

CONTEXT: Osteomas are limited almost exclusively to craniofacial and jaw bones. Histologically, they can be divided into ivory, mature, or mixed types. Osteomas may have osteoblastoma-like areas and distinguishing it from true osteoblastoma can be challenging. Some believe osteomas with osteoblastoma-like features behave more aggressively.

OBJECTIVE

To perform a clinicopathologic comparison of sino-orbital osteomas both with and without osteoblastoma-like features.

DESIGN

We studied 45 surgically excised sino-orbital osteomas. Tumors were categorized as ivory, mature, or mixed type and presence of osteoblastoma-like areas and Paget-like bone were noted. Clinical features of those with and without osteoblastoma-like areas were compared.

RESULTS

Men outnumbered women (3:2); median age was 37 years. Frontal sinus was the most common location (62%) followed by ethmoid and maxillary sinuses. Twelve tumors (27%) involved the orbit, 2 primarily and 10 secondarily. All cases were symptomatic with headache, sinusitis, visual changes, pain, and proptosis being most common. Seventeen tumors (38%) had osteoblastoma-like areas. Extension into an adjacent sinus/anatomic compartment was more common in osteoblastoma-like tumors (47% versus 29%), including more frequent orbital involvement (41% versus 13%). Visual changes were more frequent in the osteoblastoma-like group. Distribution of histologic subtypes and Paget-like bone were similar between the 2 groups. Osteomas with osteoblastoma-like features were more often incompletely excised (25% versus 14%). However, clinical recurrence was less common (8% versus 27%).

CONCLUSIONS

Osteoblastoma-like features are common in sino-orbital osteomas, but it does not correlate with more adverse clinical features or worse outcome. Osteoblastoma-like areas appear to represent active remodeling within an osteoma rather than defining a distinct clinicopathologic entity. Distinguishing it from osteoblastoma may require careful histologic evaluation and radiographic correlation.