Contributed by Fenghua Zhang, MD1,2; Liam Chen, MD, PhD1
1Division of Neuropathology, Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, USA
2Department of Clinical Laboratory, The First Affiliated Hospital of Dalian Medical University, Dalian ,China
A 72-year-old woman presented with progressively hearing loss over past ten years and recently developed pain in her left ear and face. The patient had a history of migraine for most of her adult life. On physical examination, facial muscle and sensation were symmetric and hearing was intact to finger rub bilaterally. Subsequent MRI revealed an enhancing mass measuring 2.6 x 1.6 x 2.1 cm within the left lateral ventricular atrium (Figure 1a), compatible with intraventricular meningioma. There was increased perfusion and blood volume within the mass and surrounding confluent T2 hyperintensities suggestive of vasogenic edema (Figure 1b). She underwent a craniotomy and tumor excision. During surgery, it was noted that the tumor was rising off the choroid plexus. A biopsy of the mass was submitted for intra-operative consultation. Following examination of the smear and frozen section, a debulking procedure was undertaken.
Intraoperative evaluation showed a dense, diffuse infiltrate of small lymphocytes (Figure 1c), which was later confirmed on paraffin sections of the subtotal resected specimen, with frequent plasmacytoid lymphocytes and scattered plasma cells more readily observed (Figure 1d). There was minimal mitotic activity and no evidence of necrosis. Immunohistochemistry showed a predominance of CD20 positive B cells (Figure 1e) with admixed CD3 positive T cells (Figure 1f). CD138 highlighted numerous plasma cells and plasmacytoid lymphocytes (Figure 1g). Immunostains for lambda and kappa light chains showed a restricted kappa light chain. Majority of the plasmacytoid cells were positive for IgM and IgG, only a few were immunoreactive for IgA. An in situ hybridization for EBV (EBER) was negative. What is the most likely diagnosis?