Lhermitte-Duclos disease is a rare disorder characterized by a slowly enlarging mass in the cerebellum. The exact nature of this lesion remains unclear, but it has been variously characterized as hypertrophy, hamartoma or benign neoplasm. Single-photon emission computed tomography (SPECT) with (123)I-iomazenil and (99m)Tc-ethyl cysteinate dimer (ECD) display central benzodiazepine receptors that are widely distributed in the normal brain cortex, a combination of brain perfusion, enzymatic activity and blood-brain barrier function, respectively. This report describes the case of a 30-year-old man who developed Lhermitte-Duclos disease. The mass regrew after a subtotal removal 13 years earlier. The cerebellar lesion exhibited hyperperfusion and hypermetabolism on blood flow and a metabolic rate of oxygen imaging on (15)O-gas positron emission tomography (PET), as well as a hyperactivity and a defect in the uptake on (99m)Tc-ECD and (123)I-iomazenil SPECT imaging, respectively. The present Lhermitte-Duclos lesion might have the biological characteristics of both hypertrophy and neoplasm, from the perspective of results from (15)O-gas PET, (99m)Tc-ECD and (123)I-iomazenil SPECT.