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:
|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.