Pineocytoma

A pineocytoma is a tumour of the pineal gland, and has along a spectrum of differentiation. It is considered a WHO grade I / II tumour. 

Demographics and clinical presentation

Pineocytomas mostly occur in young adults, and present as a result of compression of the midbrain, with either obstructive hydrocephalus or Parinaud syndrome. Unlike pineal germinomas both genders are equally affected.

Radiographic features

Typically pineocytomas are slow growing and well circumscribed (compared to pineoblastomas which tend to be larger, and less well circumscribed) tumours. They tend to be solid, although focal areas of cystic change, or haemorrhage do occur, making their distinction from pineal cysts sometimes problematic.

On both CT and MRI the solid components enhance brightly. 

Typically the pineal calcification is peripheral, or 'exploded'. This is the same pattern as is seen in other pineal cell origin tumours (pineal parenchymal tumour with intermediate differentiation and pineoblastomas) but is helpful in distinguishing these tumours from pineal germinomas which then to 'engulf' pineal calcification. 

Differential diagnoses

• other pineal parenchymal tumours
  
  • pineal parenchymal tumour with intermediate differentiation
  • pineoblastoma : larger, poorly defined
  • papillary tumour of the pineal region
• germ cell tumours
  • germinoma
    • marked male predominance
    • engulfed calcification
      
  • embryonal carcinoma
  • choriocarcinoma
  • teratoma: may contain fat
• astrocytoma of pineal gland
• metastasis
• pineal cyst : at most thin (< 2mm) peripheral enhancement