Multiple Lucent Skull Lesions

Miral D. Jhaveri, MD

DIFFERENTIAL DIAGNOSIS

Common

Skull Normal Variants
- Venous Lakes
- Emissary Veins, Transcranial
- Arachnoid Granulations
- Prominent Convolutional Markings
- Parietal Foramina
Treatment-Related
- Burr Holes
- Surgical Defects, Calvarial
Metastases, Skull
Osteoporosis
Myeloma

Less Common

Langerhans Cell Histiocytosis
Hyperparathyroidism
Lymphoma, Metastatic, Intracranial
Hemangioma
Leukemia
Osteomyelitis, Skull
Osteoradionecrosis
Chiari 2 (Lacunar Skull)

Rare but Important

Neurosarcoid
Neurofibromatosis Type 1 (Lambdoid Defects)
Syphilis, Acquired

ESSENTIAL INFORMATION

Key Differential Diagnosis Issues

As with solitary lucent skull lesion, margins helpful
- Sharply demarcated: Treatment-related, myeloma
- Permeative: Metastasis, osteomyelitis
- Beveled: Histiocytosis
- Inner table involvement: Convolutional markings, arachnoid granulations

Helpful Clues for Common Diagnoses

Skull Normal Variants
- Venous Lakes
  - Diploic venous can usually be traced to area of lucency
  - Slightly ragged configuration, poorly defined margin
- Emissary Veins, Transcranial
  - Extremely variable positions
  - Common in frontal and parietal bones
  - Very thin walls
  - Communicate with meningeal veins and dural sinuses
- Arachnoid Granulations
  - Punched out defects inner table subjacent to dural venous sinuses
  - CSF density/intensity
- Prominent Convolutional Markings
  - Related to pulsation of brain
  - Inner table, frequent in children
  - Become prominent in craniosynostosis, chronic raised intracranial pressure
- Parietal Foramina
  - Two symmetric openings on each side of sagittal suture in the upper edge of parietal bones
  - Usually very small, permit passage of emissary veins
Treatment-Related
- Burr holes, shunt-related, surgical defects
- Sharply marginated
Metastases, Skull
- Permeative skull destruction ± scalp/dural soft tissue
- Often known primary malignancy
- Commonly lung, breast, renal, thyroid
Osteoporosis
- Older age group
- Spotty demineralization appearing as lucent lesions
Myeloma
- Multiple, well-circumscribed, lytic, punched out, round lesions
- Skeletal survey helpful

Helpful Clues for Less Common Diagnoses

Langerhans Cell Histiocytosis
- Sharply marginated lytic defect with bevelled margins
- Associated soft tissue mass
- Large lesions: Geographic destruction
- Brain: Thick enhancing infundibulum, absent posterior pituitary bright spot
- 2-5 years: Multifocal disease
Hyperparathyroidism
- Mottling of the cranial vault due to trabecular bone resorption
- Alternating areas of lucency and sclerosis: “Salt and pepper” skull
- Brown tumors: Multiple well-defined lytic lesions
- ↑ Parathyroid hormone
Hemangioma
- Sharply marginated expansile lesion
- Diploic space, honeycomb, or sunburst appearance pattern
- 1/3 have thin sclerotic rim
- Multiple uncommon
Leukemia
- Osteopenia with multiple lytic lesions
- Sutural diastasis: Produced by ↑ intracranial pressure
- Tubular and flat bones more commonly involved
- Skeletal survey may be helpful
Osteomyelitis, Skull
- Permeative destruction ± scalp/epidural soft tissue
- Usually occurs as a complication of trauma or sinusitis
- Brain abscess is most common complication
Osteoradionecrosis
- Mixed region of lysis and sclerosis
- Radiates outward from epicenter of radiation portal
Chiari 2 (Lacunar Skull)
- Caused by inherited mesenchymal defect, not hydrocephalus/increased intracranial pressure
- Not same as prominent convolutional markings (normal variant)
- Present at birth, largely resolves by 6 months
- Minor changes may persist into adulthood
- Involves both inner, outer tables
- Squamous portions of temporal/occipital bones, parietal bones