Histiocytic necrotizing lymphadenitis (Kikuchi-Fujimoto disease) with CNS involvement in a child.

We describe the case of a 9-year-old boy with encephalitis associated with histiocytic necrotizing lymphadenitis (HNL), also known as Kikuchi-Fujimoto disease. The child presented with unilateral cervical lymphadenopathy and fever that evolved to encephalitis in 3 weeks. Brain MRI showed bilateral temporal lobe hyperintense signal on T2 and FLAIR, hyperintense FLAIR signal in the periaqueductal gray matter, medial walls of the third ventricle, and mammillary bodies, multiple diffusion restriction foci in a central perivascular distribution and central perivascular enhancement. The perivascular distribution and nodularity of the diffusion restriction seen in this case has not been previously reported in HNL encephalitis.

Selective IgM deficiency in CD30+ cutaneous lymphoproliferative disorder.

Primary cutaneous anaplastic large cell lymphoma with local lymph node involvement was diagnosed in a 13-year-old boy with an ulcerative facial lesion and a history of skin lesions of lymphomatoid papulosis. The tumor regressed with chemotherapy. He continued to develop recurrent self-limited lesions of lymphomatoid papulosis , with a halo surrounding these lesions during the healing phase. He developed selective immunoglobulin M deficiency with decline in levels even 4 years after the chemotherapy with no recurrent infections noted and adequate IgG response to immunizations. Both peripheral blood IgM+ and memory B cells were low, suggesting a possible cause-effect relationship between selective immunoglobulin M deficiency and chronic CD30+ cutaneous lymphoproliferative disorders.