Best Post of June 2010: A 38-year-old HIV-infected patient presenting with seizures

The next in our Best of the Month series is from June 29, 2010:

The Diagnostic Slide Session at the recent American Association of Neuropathologists annual meeting in Philadelphia featured a fascinating case by Dr. Sandra Camelo-Piragua, Ronald A. Goerss, and David N. Louis of Massachusetts General Hospital. The case was that of a 38-year-old AIDS patient who had been only intermittently compliant with his HAART therapy. He presented to the hospital with seizures in 2009 after a year of fluctuating neurological symptoms. Imaging studies showed the following white matter changes:

Biopsy showed a marked lymphocytic infiltrate, which included diffuse, perivascular, and follicular arrangements:

Macrophages were also present:

The following stains for organisms were all NEGATIVE: AFB, GMS, HSV1, HSV2, CMV, HHV8, and toxoplasma. An H&E/LFB stain demonstrated that this was a leukoencephalopathic process:

Immunohistochemistry of one of the lymphoid follicles indicated that the lymphoid infiltrate was a reactive, rather a neoplastic process:

Polyoma virus immunohistochemistry for the SV40 (a surrogate marker for JC virus due to cross-reactivity) was found to be positive:

So, the final diagnosis rendered was Progressive Multifocal Leukoencephalopathy (PML) with concomitant Immune Reconstitution Inflammatory Syndrome (IRIS). IRIS is an inflammatory response in HIV-infected individuals upon initiation of HAART therapy. The immune response can be so robust as to cause morbidity, particularly with the brain is involved. Thanks to Dr. Camelo-Piragua for providing the images associated with this interesting case, and I wish her the best of luck in her upcoming move to Ann Arbor where she will take a position on the faculty at the University of Michigan!