Frontal lobe epilepsy with focal neuronal lipofuscinosis – Case report of a rare entity

Focal neuronal lipofuscinosis is a unique neuronal pathology, characterised by accumulation of lipofuscin within dysmorphic neurons. We report a case of 12-year-old female with drug resistant epilepsy since one and a half years of age. MRI brain showed right frontal dysplasia, and PET showed right frontal hypometabolism. She underwent electrocorticography-guided resection of the lesion. Histopathology revealed cortical dyslamination with several hypertrophic dysmorphic neurons showing intracytoplasmic granular accumulation of lipofuscin which was positive for Periodic acid–Schiff, Luxol fast blue, and autofluorescent. Ultrastructural examination revealed intracytoplasmic, non-membrane bound, electron dense material with characteristics of lipofuscin filling the neuronal soma. On immunohistochemistry, the neurons showed ring-like non-phosphorylated and phosphorylated neurofilaments enveloping the lipofuscin material, few being positive for ubiquitin. It is important to be aware of this rare entity as it can be associated with family history of seizures and has a distinct pathobiology.