Pure Endoscopic Endonasal Removal of Unusual Anterior Skull Base Aneursymal Bone Cyst Extending to the Frontal Lobe

AbstractAneurysmal bone cysts (ABCs) are benign, nonneoplastic,hemorrhagic, and expansile osseous lesions that present most frequently at age younger than 20 years. Aneurysmal bone cysts typically involve long bones of extremities, thorax, pelvis, or spinal column. Skull base involvement is very rare. The authors report the case of a 23-year-old woman with ABC of the skull base and total removal of lesion with pure endoscopic endonasal approach. The patient had presented with nasal obstruction for 6 months. Physical and neurological examination findings were normal except for bilateral anosmia. Cranial magnetic resonance imaging (MRI) revealed a tumor occupying ethmoid sinuses anterior skull base that extended into bilateral frontal lobes. The patient underwent pure endoscopic endonasal surgery, and the tumor was resected gross-totally. Histologic examination revealed ABC. Consequently, ABC should be considered in differential diagnosis of skull base pathologies. Endoscopic endonasal surgical approach is a safe, minimally invasive, and effective way in the treatment of these tumors.

Aneurysmal bone cysts are members of benign fibrosseous lesion groups such as ossifying fibroma, fibrous dysplasia, and benign osteoblastoma.1–4Aneurysmal bone cystswere first described by Jaffe and Lichtenstien as a nonneoplastic, hemorrhagic, multiseptate cystic and expansile benign osseous lesions in 1942.5–9 They are most commonly found in long bones of extremities, thorax, pelvis, and spinal column; and skull base involvement is very rare.5,10 Most patients having ABCs are younger than 20 years.5,6,11,12 According to Lichtenstien, ABCs could be lesions that developed secondary to circulation impairment as seen in venous thrombosis or arteriovenous malformation.13,14 Clinical findings of ABCs depend on affected region. In cranial involvement, headache, nasal obstruction, and cranial nerve paralysis are remarkable for ABCs.12,13,15 Radiography of aneurysmal bone cysts generally shows an expansile cystic lesion with a honeycomb or a soapbubble appearance.1,16 Treatment options of ABCs include surgical resection, curettage, cryotherapy, sclerotherapy, and radiotherapy.5,7,17–22 Many transcranial surgical approach with different succes rates, cosmetic problems, and reconstruction problems have been used for surgical resection of skull baseABCs until today.1,5,11 Surgical resectionwith gross-total excision has perfect outcome and considered as best approach for treatment of ABCs.1,11,23,24 The authors present gross-total resection of a rare ABC that occupies anterior skull base and extends to bilateral frontal lobes with pure endoscopic endonasal surgical approach.