Friday, July 30, 2010

Solitary Skull Lesions

A mnemonic for solitary skull lesions is "I help me"
  • Infection: Permeative margin
  • Hemangioma: Well-circumscribed diploic space lesion with a "Spoke wheel" or "reticulated" pattern
  • Epidermoid/dermoid: Epidermoid has sclerotic margins
  • Leptomeningeal cyst: Smoothly marginated skull defect. "Growing fracture" refers to dural herniation and expansion of defect.
  • Plasmacytoma: Scalloped, poorly marginated, non-sclerotic skull base margin.
  • Paget: AKA osteoporosis circumscripta. Lytic phase shows a well-defined defect with involvement of the inner > outer tables. More common in the frontal bone. Look for cortical thickening and coarse trabeculation.
  • Post surgical: Well-marginated
  • Metastases: Permeative margin
  • Eosinophilic granuloma: Beveled edge (inner table involved to a greater extent than the outer table). Properly called Langerhans cell histiocytosis under the new classification of histiocytic disordere.
  • Encephalocele: Conegnital form is usually parietal or occipital.
In addition to being needlessly long, this mnemonic has the added benefit of being impossible to remember.

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