Intradiploic epidermoid cysts represent epidermoid cysts that occur in the diploe of the skull.
Painless slowly progressive scalp swelling.
- epidermoid cysts may be congenital (most common, arising from ectodermal inclusion during neural tube closure and subsequently remain within the cranial bones) or acquired (e.g. post-surgical or post-traumatic implantation) 4
- intradiploic epidermoids are less frequent than the intradural variety 1
Intradiploic epidermoids occurs within the frontal, parietal, occipital, sphenoid bones as well as the spine 1.
- rounded or lobulated area of bone destruction, well-delineated sclerotic scalloped margins
- non-enhancing hypodense lesion with sharply demarcated bony defects and zones of calcifications
- it may alter the outer or inner tables of the skull (the inner table more than the outer)
- T1: slightly hyperintense to the CSF
- T2: isointense/hyperintense to the CSF
- FLAIR: hyperintense to the CSF space
- DWI: restricted diffusion with characteristic hyperintensity
- T1C+: none
History and etymology
The radiological pattern of intradiploic epidermoids was first described by Cushing in 1922.
- 1. Osborn AG, Salzman KL, Barkovich AJ. Diagnostic Imaging. Lippincott Williams & Wilkins. (2009) ISBN:1931884722. Read it at Google Books - Find it at Amazon
- 2. Krupp W, Heckert A, Holland H et-al. Giant intradiploic epidermoid cyst with large osteolytic lesions of the skull: a case report. J Med Case Rep. 2012;6 (1): 85. doi:10.1186/1752-1947-6-85 - Free text at pubmed - Pubmed citation
- 3. www.ajns.paans.org. Forbidden. Read relevant article. Accessed on 19/01/2016
- 4. Osborn AG, Preece MT. Intracranial cysts: radiologic-pathologic correlation and imaging approach. Radiology. 2006;239 (3): 650-64. doi:10.1148/radiol.2393050823 - Pubmed citation
The differential diagnosis for bone tumours is dependent on the age of the patient, with a very different set of differentials for the paediatric patient.
- bone-forming tumours
- cartilage-forming tumours
- chondromyxoid fibroma
- fibrous bone lesions
- bone marrow tumours
- other bone tumours or tumour-like lesions
- aneurysmal bone cyst
- benign fibrous histiocytoma
- giant cell tumour of bone
- Gorham massive osteolysis
- haemophilic pseudotumour
- intradiploic epidermoid cyst
- intraosseous lipoma
- musculoskeletal angiosarcoma
- musculoskeletal haemangiopericytoma
- primary intraosseous haemangioma
- simple bone cyst
- impending fracture risk