BACKGROUND : Osteoid osteoma is a common benign bone tumor frequently seen in the frontoethmoid region. However, involvement of the skull base is rare, with few cases previously reported.

OBSERVATIONS : The authors report two cases of spontaneous, symptomatic frontoethmoidal osteoma: one presented with neurological deficit secondary to tension pneumocephalus and the other with cerebrospinal fluid leakage. The first case was managed with a transfrontal sinus craniotomy and pneumocephalus decompression with osteoma resection and skull base reconstruction. The second case was managed with a uninaral endoscopic endonasal approach to the anterior skull base with osteoma resection and reconstruction.

LESSONS : Given the paucity of cases with associated tension pneumocephalus described in the literature, it was relevant to describe the authors' experience with surgical decision-making and the expected outcomes among patients with this pathology when using minimally invasive techniques.