[2] Main clinical signs and symptoms include:[citation needed] Patients with Lhermitte–Duclos disease and Cowden's syndrome may also have multiple growths on skin.

MICROSCOPY (lhermitte-duclos disease) 1>Enlarged circumscribed cerebellar folia 2>internal granular layer is focally indistinct and is occupied by large ganglion cells 3>myelinated tracks in outer molecular layer 4>underlying white matter is atrophic and gliotic In Lhermitte–Duclos disease, the cerebellar cortex loses its normal architecture, and forms a hamartoma in the cerebellar hemispheres.

Like cowden syndrome, patients with Lhermitte–Duclos disease often have mutations in enzymes involved in the Akt/PKB signaling pathway, which plays a role in cell growth.

10q leads to increased activity of AKT and mTOR pathways, and patients should be tested for these mutations because they may be at risk of other tumors and cancers in other parts of the body.

[citation needed] Lhermitte–Duclos disease is a rare entity; approximately 222 cases of LDD have been reported in medical literature.