Solid aneurysmal bone cyst of the clivus mimicking malignancy: A rare case report

Abstract

Aneurysmal bone cysts (ABCs) are rare, benign osseous lesions, with the solid variant being particularly uncommon and exceedingly rare in the skull base, posing significant diagnostic challenges due to its mimicry of malignant neoplasms. We present a case of a 67-year-old man with progressive visual disturbances whose MRI revealed a heterogeneously enhancing, solid lesion of the clivus and sphenoid bone, prompting differential diagnoses including chordoma. Endoscopic endonasal resection and crucial histopathological and immunohistochemical analyses, negative for common tumor markers but positive for CD34 in vascular structures, confirmed a solid variant ABC. This case highlights the profound diagnostic complexity of such skull base lesions, underscoring the critical importance of integrating imaging, histology, and immunohistochemistry. By presenting this rare entity, we aim to enhance clinical awareness of solid variant ABCs, emphasizing the necessity for meticulous diagnostic evaluation to prevent misdiagnosis and potential overtreatment, while also recommending long-term follow-up due to recurrence potential