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.