Classification of Pineal Gland Tumors

Incidence of pineal mass:

<1% of all intracranial tumors in adults; 3–8% of all intracranial masses in childhood; 9% of all intracranial masses in Asia

Symptoms of pineal region mass:

Cause: invasion / compression of tectal plate

• Parinaud syndrome:
  1. Failure of conjugate vertical eye movement (= paralysis of upward gaze)
  2. Failure of ocular convergence
  3. Mydriasis
  4. Blepharospasm (= eyelid contraction or twitch)
• precocious puberty = secretion of hCG by tumor (more common with germ cell tumor)
• pineal apoplexy = hemorrhage into pineal tumor / cyst:
  • sudden decrease in consciousness, headache
• hydrocephalus ← obstruction of aqueduct of Sylvius:
  • headache, nausea, vomiting

1. PRIMARY TUMOR
   1. Germ cell tumors (⅔)
      Frequency: 0.4–3.4% of pediatric brain tumors in Western countries; up to 11% of those in Japan / other Asian countries
      Age: 10–30 years; M÷F = 3÷1
      • forming embryonic tissue
        1. Germinoma (40–50%)
        2. Teratoma (15%)
        3. Embryonal carcinoma
      • forming extraembryonic tissue
        1. Choriocarcinoma (<5%)
        2. Endodermal sinus tumor = yolk sac tumor
        3. Mixed germ cell tumor
   2. Pineal parenchymal cell origin (<15%)
      1. Pineocytoma
      2. Pineoblastoma
      
      Pineal parenchymal cell tumors expand and obliterate the pineal architecture → “exploding” normal pineal calcifications toward the periphery
   3. Other cell origin
      1. Trilateral retinoblastoma
      2. Astrocytoma (pineal + tectal glioma)
      3. Meningioma
      4. Lipoma
      5. Ependymoma
      6. Hemangiopericytoma
      7. Cavernous hemangioma
   4. Cysts
      1. Pineal cyst
      2. Malignant teratoma
      3. AVM, vein of Galen aneurysm
      4. Arachnoid cyst
      5. Congenital inclusion cysts (dermoid, epidermoid)
2. SECONDARY TUMOR
   Metastasis: 0.4–3.8% in patients with solid tumors; lung >breast >kidney >esophagus >stomach >colon
   DDx considerations:
   • female: likely NOT germ cell tumor
   • hypodense matrix: likely NOT pineal cell tumor
   • distinct tumor margins: probably pineocytoma / teratoma / germinoma
   • calcification: likely NOT teratocarcinoma, metastasis, germinoma
   • engulfed calcifications: germinoma
   • CSF seeding: NOT teratoma
   • intense enhancement: likely NOT teratoma
   
   Serum (oncoprotein) markers:
   • choriocarcinoma β-hCG
   • embryonal cell carcinoma α-FP and β-hCG
   • endodermal sinus tumor α-FP
   • teratoma β-hCG and α-FP
   • germinoma placental alkaline phosphatase
   
   Presence of oncoproteins / engulfment of pineal calcifications help narrow the differential diagnosis.