Intradiploic epidermoid cyst.

Abstract

A 35-year-old lady, presented with approximately 5 cm X 4 cm sized\nswelling in the left parietal region since childhood. There was history\nof progressive increase in the size of the swelling since childhood.\nThere was no history of trauma. There was history of pain associated\nwith swelling since last two months. On examination, the swelling was\nsoft, non-tender and could be moved over the underlying bone. The skin\nover the swelling could not be retracted. Frontal and lateral\nradiograph of the skull showed an approximately 5 cm X 4 cm , well\ndefined osteolytic lesion in the left posterior parietal bone (Figure\n1). The inner table was scalloped and the outer table was everted\n(Figure 2). There was no evidence of calcification or periosteal\nreaction. Rest of the skull was unremarkable. For better delineation of\nthe lesion, plain and contrast enhanced axial computed tomographic (CT)\nscan was performed. Plain CT scan revealed, a 5 cm sized soft tissue\ndensity lesion seen within the diploic space of the left posterior\noccipital bone with attenuation values ranging between 20 Hounsfield\nunit (HU) to +20 HU (Figure 3). This lesion was seen to protrude\noutside the margins of the skull and the dura matter was seen\nseparately from the lesion. There was no calcification within the mass.\nOn contrast there was no appreciable enhancement. Rest of the cerebral\nparenchyma was normal.