We believe the currently accepted indications for frontal osteoma surgery are inappropriate. We propose a new osteoma classification system, below, in order to standardise surgical decisions.

Osteomas were classified based on: relationship of tumour mass to sinus size; tumour proximity to the infundibulum, destruction of sinus walls, and complications. Forty-five osteoma cases were thus classified (1971–2007), 29 of which underwent surgery (64.44 per cent).

Three stages were thus derived: I, tumour/air fraction less than one-third, tumour distant from the infundibulum, no sinusitis, and no complications (18 patients (40 per cent)); II, tumour/air fraction one-third to one-half, no infundibular obstruction, no bone destruction, no sinusitis, and no complications (six (13.33 per cent)); and III, tumour/air fraction more than one-half, partial or total infundibular obstruction, sinusitis, bone destruction, and/or complications (21 (46.67 per cent)).

Study findings suggest the following surgical indications: stage I, no surgery required, implement monitoring protocol; stage II, implement monitoring protocol, surgery may be required depending on tumour severity and general patient condition; and stage III, surgery always required. This system provides a method of standardising osteoma surgical decisions.