Halicephalobus gingivalis: a rare cause of fatal meningoencephalomyelitis in humans.

The genus Halicephalobus consists of eight species of free-living nematodes. Only one species (H. gingivalis) has been reported to infect vertebrates. Human infection is extremely rare, and only four cases have been reported in the literature. These nematodes seem to exhibit neurotropism, but their life cycle, mode of infection, and risk factors are poorly understood. Neurohelminthiases are not commonly recognized in the United States and when they do occur, pose great diagnostic challenges because of lack of appropriate non-invasive screening and/or confirmatory tests. We report a challenging case of meningoencephalomyelitis caused by a Halicephalobus sp., in which the patient had a rapidly deteriorating clinical course. The case did not raise any clinical suspicion of neurohelminthiases, although increased eosinophils were present in the cerebrospinal fluid. This case presents an opportunity to highlight the importance of considering parasitic infection in meningoencephalitis or meningoencephalomyelitis presenting atypically.

Atypical angioimmunoblastic T-cell lymphomas masquerading as systemic polyclonal B-immunoblastic proliferation.

Angioimmunoblastic T cell lymphoma (AITL) is a relatively rare peripheral T cell lymphoma derived from follicular T helper cells. AITL has a varied presentation, both clinically and morphologically. AITL can pose a diagnostic challenge as it may be difficult to identify and characterize the neoplastic cells among the polymorphous infiltrates composed of polyclonal B immunoblasts and plasma cells. In AITL, the reactive B cell and plasma cell proliferation is secondary to dysregulated secretion of cytokines such as interleukin-6 by the neoplastic follicular T helper cells. SPBIP is a condition of unknown etiopathogenesis characterized by systemic involvement by polyclonal B immunoblasts and plasma cells. We report two cases of AITL, which are presented with atypical findings making it difficult to diagnose. The cases had features similar to SPBIP. Our cases highlight the importance of screening cases of polyclonal plasmacytosis and SPBIP like cases for underlying AITL.