Solitary Parenchymal Calcification

Anne G. Osborn, MD, FACR

DIFFERENTIAL DIAGNOSIS

Common

Neurocysticercosis
Tuberculosis
Cavernous Malformation
Oligodendroglioma
Ganglioglioma
Diffuse Astrocytoma, Low Grade
Pilocytic Astrocytoma

Less Common

Arteriovenous Malformation
Ependymoma
Parasites, Miscellaneous

Rare but Important

Physiologic Calcification, Brain
“Brain Rock”
Calcified Embolus
Saccular Aneurysm
Metastasis, Parenchymal
TORCH Infection
DNET
Meningioangiomatosis

ESSENTIAL INFORMATION

Key Differential Diagnosis Issues

Solitary brain calcification includes
- True parenchymal calcification
- Some lesions that may look like they are in brain itself but are not actually in parenchyma
  - Lesion in deep sulcus (neurocysticercus cyst)
  - Lesion in vessel (calcified embolus, saccular aneurysm)
Key question: Is Ca++ solitary focus or are there multiple calcified foci in solitary mass-like lesion?
Solitary “dot-like” or globular Ca++
- Typically infectious (neurocysticercosis, TB, occasionally other rare parasites)
- Less common
  - Physiologic (habenular commissure, unilateral basal ganglia)
  - Vascular (AVM, cavernous malformation, Ca++ embolus)
- Rare = brain “rock”
Solitary mass-like lesion with clustered Ca++
- Neoplasm (many)
- Cavernous malformation

Helpful Clues for Common Diagnoses

Neurocysticercosis
- Nodular calcified (healed) stage
- Multiple (“starry sky”) > solitary lesions
- Most NCC cysts are actually cisternal (within depths of superficial sulci) > brain parenchyma, ventricles
Tuberculosis
- Healed granuloma
  - Can be single or multiple
  - Many fewer lesions than NCC
  - Occasionally solitary tuberculoma can be mass-like, mimic neoplasm
Cavernous Malformation
- Solitary > multiple
- Ca++ can be dot-like, clumped, or scattered within single lesion
- Do MR with T2* scan (GRE, SWI) to look for hemorrhage, multiplicity
Oligodendroglioma
- Cortical/subcortical mass
- Slow-growing; may erode adjacent skull
- 70-90% calcify (nodular, clumped)
- Adult > child
Ganglioglioma
- Slow-growing, cortically based neoplasm
- Child/young adult with epilepsy
- Common: Ca++ nodule, ± cysts
- May erode/remodel adjacent skull
Diffuse Astrocytoma, Low Grade
- Hemispheres > posterior fossa
- Solid > > cystic mass
- 10-20% calcify
- Infiltrates brain
- Intrinsic tendency to undergo malignant degeneration
Pilocytic Astrocytoma
- Cerebellum > optic nerve/chiasm, 3rd ventricle > pons
- Cyst with nodule (cerebellum)
- Solid mass (optic chiasm/hypothalamus, pons)
- Ca++, hemorrhage uncommon (unless pilomyxoid variant)

Helpful Clues for Less Common Diagnoses

Arteriovenous Malformation
- Little/no mass effect unless hemorrhage
- Look for enlarged feeding arteries, draining veins
- Occasional Ca++ in nidus, draining veins (phlebolith)
Ependymoma
- 3rd most common posterior fossa neoplasm in children (after medulloblastoma, pilocytic astrocytoma)
- 2/3 infratentorial (4th ventricle)
- 1/3 supratentorial (extra-ventricular, hemispheric WM)
  - Large, extensively calcified cystic/solid hemispheric mass in young child? Think ependymoma first!
- 50% of all ependymomas calcify
- Cysts, hemorrhage also common
Parasites, Miscellaneous
- Except NCC, parenchymal Ca++ rare
- Any healed parasitic infection can calcify

Helpful Clues for Rare Diagnoses

Physiologic Calcification, Brain
- True solitary, unilateral normal parenchymal Ca++ unusual
  - Basal ganglia usually bilateral, occasionally unilateral
  - Habenular commissure may Ca++
“Brain Rock”
- Dense globular parenchymal Ca++
- No infection, neoplasm, degeneration
Calcified Embolus
- In artery within sulcus, not brain parenchyma
Saccular Aneurysm
- Huge, bizarre-appearing, extensively calcified mass in adult? Think partial/completely thrombosed giant saccular aneurysm
Metastasis, Parenchymal
- Untreated metastases rarely calcify
- Breast, mucinous carcinoma, osteosarcoma metastasis may calcify spontaneously
TORCH Infection
- Multiple > > solitary
- CMV most common
- Cortical
DNET
- Almost all patients < 20 years
- Chronic epilepsy
- Well-delineated, “bubbly” appearing cortical mass
  - May remodel overlying skull
  - Gross Ca++ uncommon, hemorrhage rare
  - < 20% enhance
  - May have adjacent cortical dysplasia
Meningioangiomatosis
- Child/young adult with seizures
- Hamartomatous cortical/leptomeningeal malformation
- Meningovascular proliferation along perivascular spaces (PVSs)
- 50% associated with neurofibromatosis
- Cortical mass with Ca++ (often gyriform)
- T2 hypointense
- Plaque-like pial, linear enhancement along PVSs

Image Gallery

Axial NECT shows solitary calcified NCC cyst

, probably in depths of sulcus. This was an incidental finding in an immigrant from endemic area who has systemic NCC. No other brain lesions were identified.