The problematic issue of Kufs disease diagnosis as performed on rectal biopsies: a case report

Kufs disease, the late-onset form of a group of neurodegenerative disorders, known as the neuronal ceroid-lipofuscinoses, is characterized by intraneuronal/extraneuronal accumulation of proteins that are visible as fingerprint inclusions and granular osmiophilic deposits (GRODs) at the ultrastructural level. A problematic case of Kufs disease in a 53-year-old female affected by progressive gait disturbances, myoclonus, epilepsy, and profound dementia is presented. Laboratory, biochemical, and molecular genetic tests were unremarkable. A magnetic resonance imaging of the brain revealed a moderate atrophy over both hemispheres with no white matter changes. Ultrastructural examination of rectal mucosa biopsies showed fingerprint inclusions in perivascular smooth muscle cells. Pathological examination of autoptic tissues showed numerous intraneuronal PAS-positive, diastase-resistant inclusions corresponding to GRODs at the ultrastructural examination, but no fingerprint inclusions. Cerebellum, skeletal, and cardiac muscles, skin, and liver were unaffected. The present case illustrates the diagnostic difficulties encountered while examining Kufs disease pathological samples. Main problematic issues include (1) specificity and diagnostic value of fingerprint inclusions when found exclusively in perivascular smooth muscle cells; (2) safe distinction of GRODs from lipofuscin inclusions in cerebral tissue; and (3) reliability in using extraneural tissues and, in particular, rectal mucosa biopsies for diagnostic purposes.