Osteosarcoma of the skull base presenting as a petrocavernous pseudoaneurysm and masquerading as an intracranial abscess: illustrative case.

Background: Telangiectatic osteosarcoma (TOS) is a rare and aggressive high-grade malignant neoplasm composed of blood-filled or empty cystic spaces resembling aneurysmal bone cysts. Uncommonly, TOSs can occur in the skull base.

Observations: The authors present a case of a TOS that presented as a petrocavernous carotid pseudoaneurysm and then masqueraded as an intracranial abscess.

Successful Treatment of Concurrently Diagnosed Multiple Myeloma and Myelodysplastic Syndrome With Isolated Del(5q) With Lenalidomide, Bortezomib, and Dexamethasone.

Lenalidomide is known to be an effective therapy for multiple myeloma and for myelodysplastic syndrome (MDS) with isolated del(5q). We report the case of a patient simultaneously diagnosed with multiple myeloma and myelodysplastic syndrome with isolated del(5q) who was treated successfully with lenalidomide, bortezomib, and dexamethasone. The treatment achieved a stringent complete response of multiple myeloma and a hematologic and cytogenetic response of MDS in three months.