[1484] Pax-2(-)/Inhibin(+) Immunoprofile in Hemangioblastoma: A Helpful Combination in the Differential Diagnosis with Metastatic Clear Cell Renal Cell Carcinoma to CNS

P Banerjee, R Albadine, R Sharma, P Burger, GJ Netto. Johns Hopkins, Baltimore

Background: Hemangioblstomas, which account for up to 2.5% of all intracranial tumors, may occur sporadically or as a part of the multi-system genetic syndrome von Hippel-Lindau disease (vHL). Approximately, 25% of hemangioblastomas occur as a part of vHL, which is caused by the inherited mutation of the vHL gene on chromosome 3p25-26. Patients with vHL are also at increased risk of developing clear cell renal cell carcinoma (cRCC). Distinguishing hemangioblastomas from metastatic cRCC to the central nervous system could be at times challenging on routine H&E sections. We propose a combination of Pax2 and Inhibin immunohistochemistry panel as a helpful approach to distinguishing the two lesions.
Design: Nine hemangioblastomas were retrieved from our surgical pathology archives (2005-2006). All H&E sections reviewed by two pathologists on the study. Clinical information was gathered from electronic medical records. Representative paraffin embedded section from each case was selected for immunohistochemical analysis. Eight metastatic cRCC to CNS represented on a Metastatic RCC Tissue Microarray were also used. IHC was performed using monoclonal antibodies for Pax2 (Zymed) and Inhibin (Serotec).
Results: Hemangioblastoma: Four lesions were located within the spinal cord and 5 in posterior fossa. No documented history of von Hippel-Lindau disease was seen in any of the patients. Pax2(-)/Inhibin (+) profile was exhibited by all 9/9 (100%) examined hemangioblastomas. Inhibin staining was cytoplasmic in nature. Nuclear Pax2 staining was not present in any of the 9 lesions. Metastatic cRCC to CNS: 5/8(63%) lesions demonstarted a Pax2(+)/Inhibin (-) immunoprofile while the remaining 3(37%) lesions were Pax2(-)/Inhibin (-).
Conclusions: We suggest a panel of Pax2 and Inhibin as a useful adjunct in the differential diagnosis of hemangioblastoma vs metastatic cRCC. In our pilot group of cases, the immuoprofile of Pax2(-)/Inhibin(+) supported the diagnosis of hemangioblastoma with a sensitivity and a specificity of 100% . On the other hand, a Pax2(+)/Inhibin(-)profile supported the diagnosis of metastatic cRCC with a sensitivity of 63% and a specificity of 100%. An expanded group of lesions is being evaluated.
Category: Neuropathology

Monday, March 9, 2009 2:30 PM

Platform Session: Section H, Monday Afternoon