Seronegative panencephalitis complicated by viral encephalomyelitis in a case of Good's syndrome - a neuropathological report.

Background: The role of thymus in the immune cascade of the body is still under active clinical scrutiny. Meanwhile, there is an unravelling of myriad presentations of thymoma with effects on various organ systems. These effects arise both due to autoimmunity or a paraneoplastic process secondary to thymoma. However, an occasional patient can be a conundrum and may give no clue regarding the pathogenesis and etiology of its clinical profile.

Material And Methods: We present an enigmatic case of a 30-year-old male presenting with superficial fungal infections followed by multiaxial neurological involvement against a background of thymoma. Extensive workup for bacterial, viral, autoimmune and paraneoplastic etiologies were negative. Thymectomy confirmed thymoma (Type AB) but failed to ameliorate the progression of symptoms. He developed recurrent episodes of severe sepsis which remitted with sensitive antibiotics only to reappear again. Immunological profile showed complete absence of peripheral circulating B-cells with reversal of CD4/CD8 ratio, findings compatible with Good's syndrome. Radiological findings showed only progressive brain atrophy without any hyperintensity. He was also treated with intravenous immunoglobulins but failed to respond with the same.

Results: Autopsy revealed features of panencephalitis (neuronophagia, neuronal loss, perivascular lymphocytic cuffing and microglial nodules) with virus particles detected ultrastructurally. Although the distinction between seronegative autoimmune encephalitis versus a viral encephalomyelitis often blurs histologically, we speculated viral encephalomyelitis to have happened toward the latter part of his long illness. To our knowledge, this is a case of Good's syndrome presenting with seronegative autoimmune panencephalitis superimposed with a viral infection.