A 73-year-old female with unresolved digestive complaints was referred to our department for CT imaging of the abdomen. Unexpectedly, an oval-shaped, well delineated, intramedullary located mass was found in the spinal canal at the level of the vertebra D11 and D12. On CT imaging the mass is hyperdense to CSF, shows intramural calcification and minimal to no contrast enhancement (Fig. 1A). Proximal to the spinal mass there is a longitudinal split in the spinal cord, diastematomyelia, associated with a congenital block vertebra and hemivertebra at the level of D9–D10 (Fig. 1B). There is also an unfused spinous process of D9 and D10, an anatomical variant which is part of the spectrum of spina bifida occulta (Fig. 1C). The patient has no symptoms of low back pain and no abnormalities in the neurological clinical examination. MR imaging is required for further differentiation of the mass and shows a well-defined lesion without perilesional edema, with hyperintense signal on T1 weighted images (Fig. 2A), inhomogeneous, isointense to hypointense signal on T2 weighted images (Fig. 2B) and no significant enhancement after contrast administration. For further differentiation diffusion weighted imaging (Fig. 3A) was performed and revealed diffusion restriction with corresponding low intensity on ADC map (Fig. 3B) in the entire mass, except in the region of calcification. These findings, in association with the spinal malformations (spina bifida, diastematomyelia, block vertebra and hemivertebra) are highly specific for a congenital spinal epidermoid cyst. The diastematomyelia is best shown on the coronal T2 weighted image in Fig. 4.

A 4-year-old boy was referred to the pediatrician for an increased head circumference, noted to be in the 95th percentile. His neurological examination showed no focal neurological abnormality, cranial nerve deficit or papilledema. MRI of the brain (Fig. A) revealed a welldefined, nonenhancing, extra-axial mass in the right frontotemporal region, between the tabula interna and the insula. The mass is isointense to CSF on T1 (Figs. A, B) and T2 weighted images (Fig. C). This fluid collection suppresses completely with FLAIR and shows no restriction on DWI. There is scalloping of bone margins and medial displacement of cortical veins. Based on these imaging findings the diagnosis of a right frontotemporal arachnoid cyst was made. Five years later the patient experienced a painful, hard blow against a lamppost on the right side of the head. Five weeks after this head trauma a follow-up MRI of the brain was performed (Figs. D–F). Unexpectedly, the arachnoid cyst has regressed for the most part. Most likely, resorption of the cyst has occurred after the head trauma. There is a little linear collection of fluid in the subdural region, which is isointense on T1 weighted images (Fig. D), hyperintense on T2 weighted images (Fig. E) without suppression on FLAIR (Fig. F). T2* weighted images show no evidence of late subacute hemorrhage. Probably, there is little granulation tissue formation in reaction after trauma which causes relatively high protein content in this subdural fluid collection. Comment Arachnoid cysts are benign lesions that occur in association with the central nervous system, both within the intracranial compartment (most common) as well as within the spinal canal. They are usually located in the subarachnoid space and account for 1% of all intracranial masses. The frontotemporal region is the most commonly affected.

Background: A 72-year-old woman with personal history of metastatic renal adenocarcinoma, considered as under remission was referred for CT scan of thorax and abdomen.

Background: A newborn (male, 6 hour-old) was referred to the radiology department for imaging of a solid tumor-like nodular lesion on the vertex of the skull. The treating pediatrician wanted to exclude a (meningo)-encephalocele or other dysraphism-like lesions

Background: A few hours after birth a newborn baby developed two soft well-defined bumps situated bilaterally on the posterior part of the parietal regions of the skull. The swellings were separated by the sagittal suture and do not cross the lambdoid suture. The infant was delivered vaginally in a head-first position after a full term pregnancy (G2A1P0) without complications. There was no prolonged labour nor use of forceps, vacuum extractor or other techniques of assisted delivery.