Today we’ll do another little unknown case. You can find our other cases here:

• Case 1: 20-year-old male who died suddenly
• Case 2: 72-year-old male with right calf mass
• Case 3: 67-year-old female with pancytopenia
• Case 4: 59-year-old male with severe headaches
• Case 5: 38-year-old female with deep venous thrombi
• Case 6: 13-year-old male with cerebellar mass
• Case 7: 45-year-old male with pulmonary emphysema

In case you’re just joining us – these are cases similar to those you might see in an unknown conference in a pathology rotation or residency. Take a look at the photo and the question, then scroll down for the answer.

A 38-year-old male with advanced AIDS presents with severe headaches, fever and altered mental status, and dies several days later. An autopsy is performed, and a coronal section of the brain is shown here. Of the following, which is the most likely diagnosis?

A. Diffuse astrocytoma
B. Medulloblastoma
C. Metastatic carcinoma
D. Oligodendroglioma
E. Primary CNS lymphoma

(Scroll down for the answer)

The diagnosis in this case is primary CNS lymphoma. This is a malignancy that you almost never see in the general population. It’s way more common in immunosuppressed patients, especially patients with AIDS, who have a 1000x increased risk.

Presenting symptoms are often non-specific, and may include seizures, headaches, and constitutional symptoms. Primary CNS lymphomas are usually diffuse large B-cell lymphomas, and they generally occur as multiple, periventricular nodules which are more discrete than gliomas, but less well-defined than metastases. In the cross section of brain above, the tumor appears as a grayish, softly-demarcated area of discoloration around the ventricles.

Virtually all cases in immunosuppressed patients are associated with Epstein-Barr virus infection. Unfortunately, primary CNS lymphoma is an aggressive lymphoma which usually responds poorly to chemotherapy.