Presentation
4 month history of headache and tinnitus
Patient Data
ASNR 2016: This case was submitted as part of the American Society of Neuroradiology (ASNR 2016) Case Of The Day competition, in collaboration with Radiopaedia.org.
Large intra-axial mass in the left cerebellar hemisphere with multilobulated peripheral enhancement, and central non-enhancing area. Central non-enhancing component shows high signal on T2 weighted sequence, partially suppresses on FLAIR, and does not demonstrate increased diffusion restriction relative to brain parenchyma. Patchy blooming on susceptibility sensitive sequences suggests presence of blood products (and therefore hemorrhage) within the mass. No flow voids. No involvement of the 4th ventricle or foramina of lushka. Surrounding non-enhancing abnormal FLAIR hyperintensity in the left cerebellar hemisphere extending into the left middle cerebellar peduncle.
MRS demonstrates elevation of choline:creatine ratio, depressed NAA peak, and a large lactate peak within the tumor. No convincing elevation of rCBV.
Mass effect in the posterior fossa causes displacement and partial effacement of the fourth ventricle. Third and lateral ventricles are not particularly dilated. No evidence of transependymal fluid shift.
No other intra- or extra-axial abnormality is demonstrated.
Chest: There is a well defined pleural based lesion measuring 14mm in the posterior segment of the right upper lobe demonstrating mild contrast enhancement and tethering of the pleura. Vessels are seen traversing the lesion with no surrounding ground glass changes , calcification or features to suggest cavitation. No other focal pulmonary lesion identified. Minor ground-glass changes involve the left inferior lingula lobe. No pleural effusion. No enlarged mediastinal or hilar lymph nodes. No obvious pulmonary embolus.
Abdomen and pelvis: (not shown) Normal. No mass or evidence of metastatic disease.
MICROSCOPIC DESCRIPTION: The sections show large numbers of yeast-like organisms with morphological features of Cryptococcus spp admixed with both acute and chronic inflammatory cells and fibrin. A reactive layer is interposed between the lesion and adjacent edematous cerebellar parenchyma. No evidence of tumor is seen.
DIAGNOSIS: Left cerebellar lesion: Cryptococcosis.
Case Discussion
This is a difficult case, with the cerebellar lesion having unusual and non-specific appearances. A metastasis was considered most likely, especially in the setting of a lung mass, although even then appearances are atypical. The absence of diffusion restriction made pyogenic infections most unlikely.
The patient went on to have a craniotomy. The lesion appeared filled with translucent white material.
Histology confirmed the left cerebellar lesion as a cryptococcoma.
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