Do Meningiomas Resolve Spontaneously?
Meningiomas do not spontaneously resolve—they are persistent tumors that require either active surveillance or intervention, and there is no documented evidence of spontaneous regression in the medical literature. 1
Natural History Without Treatment
Meningiomas are benign tumors in 90% of cases that arise from arachnoid cells and persist indefinitely without treatment. 2 The available evidence demonstrates:
Asymptomatic, incidental meningiomas in adults have been detected in 2.3% of autopsies, indicating these tumors remain present throughout life rather than resolving. 1
A Finnish population-based study found that 21% of meningiomas were only identified at autopsy, confirming that untreated tumors persist until death. 1
Survival data for adults who did not undergo surgery shows cumulative relative survival of only 49% at 3 months and 25% at 15 years, compared to 93% at 3 months and 79% at 15 years for those treated surgically. 1 This stark difference reflects the progressive nature of untreated meningiomas, not spontaneous resolution.
Growth Patterns and Surveillance
Rather than resolving, meningiomas typically exhibit slow, continuous growth:
WHO grade 1 meningiomas should be surveilled with MRI every 6 to 12 months, with intervals potentially prolonged after 5 years of stability. 3
Slow growth from 8x8x10mm to 9x9x11mm over 4 years is compatible with typical benign meningioma behavior. 3
Even after complete surgical resection, up to 20% of benign meningiomas recur within 25 years, indicating the need for lifelong follow-up. 1, 4
When Observation is Appropriate
The "watch and wait" strategy does not rely on tumor resolution but rather on monitoring slow-growing tumors that may not require immediate intervention:
Asymptomatic small meningiomas (<30 mm) can be observed if they remain stable. 4
Observation is particularly appropriate for elderly patients (above 60 years) or those with significant comorbidities where treatment risks outweigh benefits. 1
Intervention becomes necessary if significant growth occurs, neurological symptoms develop, parenchymal edema appears, or seizures/increased intracranial pressure manifest. 3
Critical Pitfall
The most important caveat is that observation does not mean the tumor will disappear—it means accepting the tumor's presence while monitoring for progression that would necessitate treatment. In one adult study with 4-year median follow-up, 6 out of 47 observed patients (13%) ultimately required surgery due to tumor progression. 1 This underscores that meningiomas persist and may eventually require intervention despite initial observation.