Presentation
"Cerebellar oligodendroglioma, WHO grade II 2004. Recurrent glioma for OR". MRI in 2010 showed minimal recurrence. Amost 10 years later, presenting with a progressing lesion.
Patient Data
Status six (6) years post right occipital craniotomy with a surgical cavity in the lateral aspect of the right cerebellar hemisphere.
Lobulated well-defined extra-axial homogenous lesion in relation with the anterior aspect of the surgical cavity showing T1 isointensity and high T2 and FLAIR hyperintensity. Mild heterogeneous postgadolium enhancement. Mild to moderate restricted diffusion.
Elsewhere, periventricular white matter T2 and FLAIR hyperintensities, attributed to chronic microvascular ischemic changes.
Fifteen (15) years since prior surgery and nine (9) years since last MRI study, size progression of the known extra-axial lesion along the anterior aspect of the surgical cavity, abutting the right cerebellar hemisphere, demonstrating T1 isointensity and high T2 and FLAIR hyperintensity with heterogeneous enhancement and mild to moderate restricted diffusion.
Worsened chronic periventricular microvascular ischemic changes.
Post re-opening of right suboccipital craniotomy with expected postsurgical changes along the occipital area.
Three (3) different follow-up T2 series:
First corresponding to 10 days postop; second, 13 months postop; third follow-up showing our patient remains free of recurrence 26 months post her second resection.
Screenshot of a section of the pathology report confirming the diagnosis of recurrent cerebellar liponeurocytoma after review of the pathology study of the initial resected tumor.
Case Discussion
Cerebellar liponeurocytomas or neurolipocytomas are glioneural tumors first described in 1978 and are located mainly in the posterior fossa.
Our patient was originally treated for the right suboccipital cerebellar liponeurocytoma from an outside institution back in 2004. The earliest available brain study in our PACS system was an outside study in 2010 which showed findings suggestive of early tumor recurrence.
Presumably our patient was "lost to follow-up" as the following available study happened in 2019 at our institution when the patient presented with an history of "Cerebellar oligodendroglioma, WHO grade II 2004. Recurrent glioma for OR".
Between the 2010 and 2019 MRI studies there had been size progression of the lesion. She then underwent another right suboccipital craniotomy for tumor recurrence.
From a radiological perspective our case highlights the MRI findings of cerebellar liponeurocytomas, which are consistent with those found in the literature (Please see Abuzeid's case report in the reference as well as the related Radiopedia article).
As per the microscopic description:
"All the sections show the same appearance that show a monotonous cell population with some vague rosetting pattern focally and some acellular neuropil like areas. The cells have mainly round to oval nuclei, thin punctuated chromatin and no definite mitoses are seen. There is no nuclear pleomorphism. There is no lipomatous component. The tumoral cells are negative for GFAP, GFAP stains reactive astrocytes and processes within the tumor. They are diffusely and strongly positive for synaptophysin and most of the cells are positive for Neu-N. Chromogranin is negative.The proliferation index is around 2%. The cells are ATRX positive and IDH1 R132H negative".
The findings were not consistent with a diagnosis of oligodendroglioma (unlike provided history).
Though no lipomatous component seen in the resected recurrent tumor, lipomatous components were seen in the original resected tumor of 2004 (Please see screenshot), given a final diagnosis of recurrent cerebellar liponeurocytoma. The lack of lipomatous components could have been related to its small size at recurrence or tumor recurrence might be less susceptible to grow lipidized cells since they are thought to represent mature adipocytes.
According to the literature, the pathological diagnosis of cerebellar liponeurocytoma remains challenging with many tumors misdiagnosed for histologic mimics with high-grade potential such as oligodendroglioma and medulloblastoma or even lipomatous medulloblastoma (See Tucker et al., 2017).
Cerebellar liponeurocytoma recurrence rate is as high as 40% for patients treated surgically in a mean time of 8 to 10 years post surgery, compatible with our patient history of recurrence which progressed between 6 and 15 years post surgical resection.
Two years post surgical resection of recurrent tumor follow-up studies (See provided T2 series) show no current tumor recurrence, which would indicate cerebellar liponeurocytoma recurrence might be a slow process in the absence of atypical histological features suggestive of potential malignant biologic behavior, such as high proliferative index, necrosis, high mitotic activity, and prominent vascular hyperplasia.
Though considered to be a benign lesion, cerebellar liponeurocytoma benign nature should also be questioned as case report of extra-cranial extension (See Nsir et al., 2014) and leptomeningeal invasion (See Jenkinson et al., 2003) have been reported.
Currently, the standard of care is thought to be surgical resection with serial neuroimaging. Our patient did not receive radiotherapy; its use remains controversial as part of the treatment plan.
Special thanks to Dr. Hasiloglu Zehra for the case suggestion and for being an exemplary fellow.
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