Surgical treatment of Lhermitte–Duclos disease in a patient with clinically diagnosed Cowden syndrome: A case report

Background: Lhermitte–Duclos disease (LDD), also known as dysplastic cerebellar gangliocytoma, is a rare benign cerebellar tumor classified as the World Health Organization Grade I, characterized by hypertrophic granular cell layer replacement and a pathognomonic “tiger-stripe” appearance on T2-weighted magnetic resonance imaging (MRI). It is frequently associated with Cowden syndrome (CS), an autosomal dominant condition caused by germline mutations in the phosphatase and tensin homolog (PTEN) tumor suppressor gene, which dysregulates the phosphatidylinositol 3-kinase (PI3K)/protein kinase B/mechanistic target of rapamycin (mTOR) signaling axis and confers elevated risk for thyroid, breast, endometrial, and gastrointestinal malignancies. Surgical resection remains the primary treatment modality in symptomatic patients. Case Description: We present a 37-year-old male with a prior history of papillary thyroid carcinoma who presented with holocranial headache, nausea, vomiting, and left appendicular ataxia. MRI demonstrated a left cerebellar mass with the characteristic tiger-stripe pattern and obstructive hydrocephalus. The combination of LDD and prior thyroid cancer fulfilled the clinical diagnostic criteria for CS (PTEN hamartoma tumor syndrome); germline PTEN testing was recommended but has not yet been performed. Newly identified nonvalvular atrial fibrillation added a perioperative anticoagulation challenge. The patient underwent suboccipital median craniotomy with left C1 hemi-laminectomy and partial resection (limited debulking). Histopathology confirmed LDD. The patient made an excellent recovery and was symptom-free at 1-year follow-up, with a single postoperative MRI at 12 months demonstrating a decompressed fourth ventricle and normalized tonsillar position. Conclusion: Surgical resection is the treatment of choice for symptomatic LDD, with the primary goals of posterior fossa decompression and histopathological confirmation. The extent of resection should be individualized; even limited partial debulking can achieve durable decompression, while gross-total resection has also been reported with excellent outcomes. Diagnosis of LDD should prompt systematic screening for CS and associated malignancies. Emerging evidence supports the PTEN/mTOR pathway as a future nonsurgical therapeutic target. This case highlights the importance of recognizing rare syndromes and the favorable short- term surgical outcomes achievable with partial resection.