Thalamic Lymphoma [Neurosurgery Wiki]

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====== Thalamic Lymphoma ======

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**Thalamic Lymphoma** is a rare form of primary central nervous system lymphoma (PCNSL) that affects the **thalamus**, a deep-seated brain structure crucial for sensory processing, motor control, and consciousness. PCNSL is typically a **non-Hodgkin's lymphoma**, most commonly of the **diffuse large B-cell lymphoma (DLBCL)** subtype.

### **Clinical Features**
- Symptoms depend on the affected **thalamic region** but often include:
  - **Cognitive decline** (confusion, memory issues)
  - **Altered consciousness** (somnolence, coma in severe cases)
  - **Hemiparesis or hemiplegia**
  - **Sensory deficits** (contralateral hypoesthesia)
  - **Ataxia or movement disorders** (due to basal ganglia/thalamic involvement)
  - **Seizures** (though less common)
  - **Increased intracranial pressure** (headache, nausea, vomiting, papilledema)

### **Imaging Findings**
- **MRI with contrast:**
  - **Homogeneous enhancement** on **T1-weighted post-contrast** images
  - **Iso- to hypointense on T2/FLAIR**
  - **Restricted diffusion on DWI**
  - **Minimal perilesional edema** (less than gliomas)
  - **No necrosis or hemorrhage** (unlike glioblastoma)
- **PET scan:**
  - **Hypermetabolic lesion** (high FDG uptake)

### **Differential Diagnosis**
- **Glioblastoma multiforme (GBM)**
  - More heterogenous enhancement, necrosis, ring-enhancing lesions
- **Thalamic infarct**
  - No contrast enhancement, stroke history
- **Demyelinating disease (e.g., multiple sclerosis, ADEM)**
  - Multifocal, periventricular distribution
- **Infectious causes (toxoplasmosis, TB, fungal abscess)**
  - Immunosuppressed patients, multifocal ring-enhancing lesions

### **Diagnosis**
- **Stereotactic biopsy** is crucial to confirm the diagnosis, as imaging alone is not definitive.

### **Treatment**
- **High-dose methotrexate (HD-MTX)-based chemotherapy**
  - Often combined with **rituximab** and **temozolomide/procarbazine**
- **Whole-brain radiation therapy (WBRT)** (for refractory or recurrent disease)
- **Corticosteroids** (can reduce tumor size but may obscure biopsy results)
- **Autologous stem cell transplantation** (in select cases)

### **Prognosis**
- Median survival: **2-5 years** with optimal therapy
- **Poor prognosis factors:**
  - Age >60 years
  - Poor performance status
  - Lack of complete remission after initial therapy