Sinonasal Aneurysmal Bone Cyst Invading the Frontal Skull Base: A Case Report

Background: Aneurysmal bone cysts (ABCs) are rare, nonneoplastic, expansible, osteolytic, and multiseptated cystic lesions with variable sizes. Despite their benign nature, ABCs are locally aggressive and destructive of the affected bone and surrounding structures. They can arise anywhere in the body but are commonly localized in the metaphysis of long bones. Skull base involvement accounts for 2 to 6% of the cases, and of those, the incidence of paranasal sinuses lesions are seldom reported.

Case Presentation: We report a 7-year-old girl who presented with rapidly progressive painless bilateral proptosis with hypertelorism and bilateral nasal obstruction for 2 months with a progressive decrease in visual acuity. Radiographic imaging findings coincide with ABC. It revealed multiple cystic lesions with conspicuous fluid levels originating from the ethmoid bone, extending into the frontal skull base, and compressing adjacent structures. The biopsy was taken through the endoscopic transnasal approach; the lesion was very bloody during the procedure. For that, a cerebral angiogram was done; there were multiple tiny feeders with no major feeders amenable for embolization. The patient underwent uneventful surgical excision for the lesion by a combined bifrontal craniotomy and endoscopic endonasal approach in the same sitting. A gross total excision was achieved. The histopathological evaluation confirmed the diagnosis of primary ABC. Postoperative, there was a significant improvement in bilateral proptosis and visual acuity.

Conclusion: Given the rarity of ABCs' presence in the sinonasal cavity with extension to the frontal skull base and the lesion's bloody nature is considering challenging in management. A multidisciplinary approach should be considered in such cases.

Publication History

Article published online:
12 February 2021