Introduction. Focal cortical dysplasia (FCD) is increasingly recognized as a cause of symptomatic epilepsy in children. Recently, it has been proposed that human papillomavirus (HPV) infection during fetal development plays a causal role in the pathogenesis of FCD type IIB, characterized histologically by the presence of dysmorphic neurons and balloon cells. Two groups have shown evidence of HPV-16 (by DNA PCR and immunohistochemistry) in a very high proportion of surgical resection specimens meeting criteria for FCD IIB, but in virtually no brain tissue specimens without FCD (1,2). We sought to examine the correlation between HPV-16 infection and FCD IIB in an independent surgical cohort.

Methods. We queried a database of surgical biopsy material for cases of FCD between 1995 and 2013. Twenty cases met criteria for FCD IIB on neuropathological review, and 6 samples were tested for HPV-16 by DNA PCR. Immunohistochemistry for HPV P16 and BCL2 was performed in a subset of samples.

Results. None of the samples tested (0/6) was positive for HPV by DNA PCR. Immunohistochemistry showed no P16 staining of balloon cells or other neuronal cells, using cervical transformation zone as a positive control. In one sample, P16 labelled rare small cells which appeared to be lymphocytes. BCL2 highlighted a reactive astrocytosis.

Conclusion. These results do not support the hypothesis that HPV-16 infection is causally related to the pathogenesis of FCD IIB.