Brain Pathology Case of the Month - June 2015

Contributed by Alcidea da C. Rosa, MD1; Marcus Vinicius Pinto, MD2 ; Victor Hugo R. Marussi MD3; Nathalie H. Silva Canedo, MD, PhD;4; Luiz Felipe R. Vasconcellos, MD, MSc1
    1 Division of Neurology, Instituto de Neurologia Deolindo Couto, Federal University of Rio de Janeiro, Brazil.
    2 Division of Neurology, Hospital Universitário Clementino Fraga Filho, Federal University of Rio de Janeiro, Brazil.
    3 Division of Neuroradiology, Medimagem, Hospital Beneficência Portuguesa, São Paulo, Brazil.
    4 Division of Neuropathology, Department of Pathology, Hospital Universitário Clementino Fraga Filho, Federal University of Rio de Janeiro, Brazil.


A 55-year-old Brazilian man, with previous history of bariatric surgery developed acute weakness of his lower limbs that started six weeks prior to his admission. He started with paresthesias in lower limbs followed by ascending and asymmetrical paraparesis. He was unable to walk weeks later. He had no pain, no upper limbs weakness and no loss of bowel or bladder control. Physical examination revealed paraparetic gait, and flaccid asymmetric paraparesis (left > right). Deep tendon reflexes were absent in the legs, with indifferent plantar response. Electroneuromyography was consistent with an acute inflammatory demyelinating polyradiculoneuropathy (Guillain-Barré syndrome). MRI of neuroaxis showed diffuse nodular abnormalities of the leptomeninges, more pronounced in dural sac where formed intra-rachidian mass (Fig 1) and hemorrhagic extra-axial nodular lesions in posterior fossa, basal cisterns and subarachnoid space of cerebral hemispheres (Figs 2 and 3). A second MRI showed larger lesions and more of them (Figs 4 and 5) as well as a new cerebral hemorrhage (Fig 6). An extensive search for the primary site was negative (chest and abdominal CT, cervical and testicular ultrasonography). Cisternal puncture didn't reveal any neoplastic cells and immunophenotyping demonstrated normal lymphocytes. A biopsy of the lesion (dural sac) was performed.


H&E stains revealed highly infiltrative lesion affecting meninges and nerve bundles (Fig 7), formed of cells with intense pleomorphism, nuclear hyperchromasia, high mitotic index, arranged in both sheets and individually infiltrating cells (Fig 8). Histogenesis was determined by IHC that revealed negative immunostaining for cytokeratins, GFAP, EMA, myeloperoxidase, CD3 and CD20. However, S100 (Fig 9) and Melan-A (Fig 10) showed strong positive staining of the tumor cells. No pigmentation was noted. Two weeks later, this patient expired after a large intracranial bleed. Autopsy examination revealed a 1cm black nodular lesion in the stomach, next to the bariatric surgery scar. Immunohistochemical analysis revealed the same immunopattern as the meningeal metastasis. What is your diagnosis?


International Society of Neuropathology