Spontaneous Resolution of Late-Onset, Symptomatic Fluid Collection Localized in the Meningioma Resection Cavity: A Case Report and Suggestion of Possible Pathogenesis.

Postoperative complications after brain tumor surgery occur occasionally and it is important for clinicians to know how to properly manage each complication. Here, we described a rare case of late-onset, subdural fluid collection localized at the resection cavity that caused motor weakness after convexity meningioma resection, requiring differentiation from an abscess, to help clinicians determine treatment strategies. A 58-year-old right-handed female was admitted to the hospital with a headache and posterior neck pain. Brain computed tomography (CT) scans and magnetic resonance (MR) images showed a homogeneously enhanced, calcified, and multi-lobulated mass adjacent to the right motor strip without perilesional edema. The patient underwent surgery without incident or residual deficit and was discharged from the hospital in good condition. Six weeks after surgery, the patient complained of left arm monoparesis without infection-related symptoms. Brain imaging studies showed a localized fluid collection in the resection cavity with an enhanced margin and perilesional edema. Diffusion restriction was not detected. After three months of conservative treatment without surgery or antibiotics, she recovered from the neurologic deficits, and brain imaging studies showed the spontaneous regression of the fluid collection and perilesional edema. Late-onset, localized fluid collection at the resection cavity, which is similar to an abscess, could occur three to eight weeks after meningioma resection. When there are predisposing factors, including blood components and hemostatic materials in the surgical cavity, it is important for clinicians to understand this type of complication and choose conservative management as a feasible strategy.