Procedure: Debulking of the shell, aspiration of the contents, microscopic resection of cystic components with preservation of the inner shell and instillation of artificial bone for bone remodeling and healing.

Gross description: The specimens received in two containers:, labeled with the patient's name and medical record number. Part 1 (received fresh for intraoperative consultation), labeled "spinal tumor” consists of multiple fragments of bony and soft hemorrhagic tissue measuring in aggregate 2.0 x 2.0 cm. Part 2 (received in formalin), labeled "spinal tumor" consists of multiple fragments of bony and soft hemorrhagic tissue measuring 3.0 x 2.0 x 0.4 cm. 

Microscopy: Sections show blood, reactive trabecular bone and a fragment of fibrous tissue (septum) which forms a cystic space that is filled with blood. Parallel arrays of osteoid trabeculae along the septum and rare osteoclast-like giant cells are also noted. Negative for malignancy.

Diagnosis: Aneurysmal bone cyst.