Tuesday, August 21, 2012

Best Post of March 2012: Spinocerebellar Ataxia Type 6 autopsy photographs

The next in our "Best of the Month" series is from March 19, 2012:

On the left is the brain of an 82-year-old patient with a diagnosis of spincocerebellar ataxia, type 6 (SCA6). On the right is the brain of a 96-year-old "control" patient with Alzheimer disease:

Note comparative diminution of the cerebellum in the SCA6 patient.  Here's a closer look at the cerebellum:
SCA6 is one several autosomal dominant cerebellar ataxias. SCA6 results from a CAG trinucleotide repeat expansion in the CACNA1A gene on chromosome 19p.

Thursday, August 9, 2012

A case of renal cell carcinoma metastatic to a meningioma

A 74-year-old woman with a history of a seizure disorder had been followed for several years with a stable and unsymptomatic left parasagittal dural-based brain tumor presumed to be a benign meningioma. Recently, though, the lesion increased in size and hemorrhaged, leaving her significantly paretic on the right side. Neurosurgery thereupon performed a craniotomy for tumor removal. Intraoperative frozen section diagnosis was meningioma. But, upon receipt of the permanent sections, I was impressed by the staghorn vessels at low power and hemangiopericytoma immediately came to mind.
Staghorn vessels prominent in region below dot marks
Psammoma body consistent with original impression that this was simply a meningioma
Whirled architecture consistent with meningioma
I was obviously dealing with a meningioma, but something else was going on in that area featuring the staghorn vessels. This region exhibited a different histomorphology:

Clear cells
High-power view of clear cell portion of specimen
This dual morphology puzzled me. I then discovered that back in 2003 the patient had undergone a radical nephrectomy for renal cell carcinoma. Surgical margins of the nephrectomy specimen were free of tumor. I retrieved the 2003 nephrectomy specimen, which looked quite similar to the clear cell portion of the brain tumor:
Nephrectomy specimen from 2003 showing renal cell carcinoma, clear cell type
I thereupon went back to the brain tumor specimen and did some immunohistochemical stains, including RCC for suspected renal cell carcinoma metastasis:
Positive RCC Immunohistochemistry
I had a case of renal cell carcinoma metastatic to a meningioma! Such a case had been reported in the literature before:

Han, HS, et al. Metastatic renal cell carcinoma in a meningioma: a case report. J Korean Med Sci. 2000 October 15 (5):593-597.

Here's case number two!

Follow-up: The patient received radiation to the tumor bed and is recovering.