Presentation
Ataxia.
Patient Data
A large cerebellopontine angle mass with a peripherally calcified component anteriorly is noted. Relatively prominent but heterogeneous enhancement is present.
A right cerebellopontine angle lesions is demonstrated composed of two parts: an anterior centrally cystic part with peripheral calcification; and a more posterior part with more typical appearances.
The posterior component is slightly hyperintense to brain parenchyma on T1 and T2 weighted imaging and demonstrates very homogeneous and intense contrast enhancement. It somewhat restricts (DWI and ADC) in keeping with the highly cellular nature of these tumors.
The anterior component is more unusual, demonstrating a central cystic region. Cystic meningiomas are an uncommon variety and the cysts are variably located with respect to the tumor (see the cystic meningioma article). Calcification in meningiomas can be due to a variety of causes (chondroid metaplasia, ossification and psammoma bodies).
The absence of extension into the internal acoustic meatus, and presence of a dural tail (best seen on coronal post contrast sequences) is helpful in excluding a cystic acoustic schwannoma, which is by far the most common cystic cerebellopontine angle mass.
Vertebral injection (right) demonstrating early tumor blush with persistence - the so-called mother-in-law sign (note that it is not very obvious unless you deliberately contrast its enhancement with that of normal brain (e.g. occipital lobes).
Case Discussion
This case elegantly demonstrates a number of the different appearances which meningiomas can have.
The patient went on to have a retrosigmoid craniotomy and excision of the tumor.
HISTOLOGY
MICROSCOPIC DESCRIPTION:
The sections show a moderately cellular meningioma. The tumor comprises whorls and fascicles with psammoma bodies (psammomatous meningioma). The tumor cells have ovoid nuclei with no significant nuclear pleomorphism. Mitoses are inconspicuous. Several blood vessels contain foreign body material, in keeping with preoperative embolization. There is a small amount of necrosis, which is likely to be associated with the embolization. No brain parenchyma is included in the biopsy. There is no atypical or malignant change.
FINAL DIAGNOSIS: Meningioma (WHO Grade I).
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