Contributed by Robert Conway, BA1, Vesna Kaluza, MD2, Kenneth Schwartz, MD1, Howard T. Chang, MD, PhD3
Departments of 1Medicine, 3Neurology and Ophthalmology, Michigan State University, East Lansing, MI 48824, USA, and Departments of 2Oncology, and 3Pathology, Sparrow Hospital, Lansing, MI 48912, USA
A 77-year old woman presented with progressive dizziness over several months. She also reported bilateral tinnitus, but denied headache. Physical exam revealed an unsteady, wide based gait, slow finger to nose test bilaterally, and inability to walk toes to heel. The patient had been diagnosed with mantle cell lymphoma (MCL) three years ago and she has completed six cycles of bendamustine and rituximab, followed by 2 years of rituximab maintenance therapy that was completed two months prior to onset of her symptoms. A recent bone marrow biopsy showed no evidence of residual lymphoma. MRI of the brain (Fig. 1) showed a right cerebellar lesion with central high T2 signal and peripheral rim enhancement.
Stereotactic biopsy of the cerebellar lesion showed small fragments of cerebellar tissue with focal small lymphocytic infiltrates, gliosis, granulation tissue, and reactive changes, including some atypical large glial nuclei (Fig. 2). Immunohistochemistry reactions for CD3, CD20, cyclin D1 and CD68 (Fig. 3) revealed that virtually all lymphocytes are T cells. Stain for Cyclin D1 did not label the lymphocytes, but labeled scattered glial nuclei, including some of the large atypical glial nuclei. Stain for CD68 revealed many macrophages/microglia. Stain for Ki67 showed focally increased labeled nuclei in both lymphocytes and atypical glial cells (Fig. 4). Stain for p53 labeled scattered atypical glial nuclei (Fig. 4). What is your diagnosis?