Objective and importance: Lhermitte-Duclos disease, or dysplastic cerebellar gangliocytoma is a rare entity characterized by a hamartomatous lesion in the posterior fossa. Cowden's syndrome, or hamartoma-neoplasia syndrome is a rare underdiagnosed autosomal dominant genodermatosis with high incidence of malignant tumors. Several recent reports suggest that Lhermitte-Duclos disease may be a component of Cowden's syndrome.
Clinical presentation: We report two cases of Lhermitte-Duclos and Cowden disease occurring in adult patients. A 40-year-old woman had symptoms of raised intracranial pressure and macrocephaly. She displayed the stigmata of fibrocystic breast disease, thyroid goitre. Clinical examination showed mucocutaneous lesions. Her mother, brother and uncle had manifestations of Cowden's disease. An asymptomatic 38-year-old male had bilateral optic nerve drusen related to a cerebellar neoplasm. He exhibited manifestations of Cowden's syndrome and his familial history confirmed this hypothesis.
Intervention: The first patient was operated on for Lhermitte-Duclos disease. A conservative strategy was performed for the second patient and the clinical and imaging follow-ups were uneventful over 5 years.
Conclusion: We stress the possibility that Lhermitte-Duclos and Cowden disease might be a peculiar form of phakomatosis. A conservative strategy can be chosen without neurological signs because of slow tumor growth. However, these patients should be carefully examined and followed up because of the risk of future malignancy.