Distinguishing mimics from true hemorrhagic cavernous malformations.

Cavernous malformations (CM) are angiographically occult vascular malformations. CM appear as discrete, small lesions with mixed-signal characteristics on T2 reflecting the underlying pathology. However, the appearance is not pathognomonic. Distinguishing true CM from hemorrhagic tumors can be difficult. We report 5 cases of tumors mimicking CMs. We compared clinical, initial radiologic features, and MRI evolution between 5 tumor mimics and 51 true hemorrhagic, sporadic, brain CM. Compared to true CM, mimic patients were older (47.0 vs. 38.3 years; p = 0.076) and more likely to have a history of primary neoplasm (60% vs 12%; p = 0.0267). Radiologically, the CM mimics demonstrated a higher likelihood of lesion enhancement on the initial diagnostic MRI (60% vs. 16.7%%; p = 0.0609). On follow-up MRI (<1 year after baseline), CM mimics typically had persistent edema (100.0% vs. 6.25%, p = 0.0003) and demonstrated mixed density on ADC (100% vs. 32.1%; p = 0.0199) as well as increased likelihood of enhancement (100% vs 25.8, p = 0.0852). CM mimics were less likely to evolve to Type 2 or 3 lesions (25.0% vs. 84.4%, p = 0.0278). Clinical and radiologic factors may distinguish tumor metastases from true hemorrhagic CM. CM mimics should be suspected in older patients with a history of neoplasm and contrast enhancement on initial MRI. A repeat MRI within 90 days post-initial hemorrhage should be considered to confirm CM diagnosis. Persistent edema without rebleed, lesion enhancement, mixed signal on apparent diffusion co-efficient, and persistence of a Type 1 lesion should raise suspicion of a metastatic tumor.