Torcular pseudomass: a potential diagnostic pitfall in infants and young children.
BACKGROUND
Incidental findings on brain MRI may constitute a diagnostic pitfall. We observed an incidental extra-axial midline rounded pseudomass between the torcular Herophili and the occipital squama, with spontaneous resolution, which we called "torcular pseudomass."


OBJECTIVE
We investigated the frequency, imaging features, natural history and developmental background of this finding in a large group of infants and young children.


METHODS
We conducted a single-center retrospective study by reviewing all brain MRIs performed in children younger than 3 years between 2007 and 2013 in a specialized pediatric hospital. We looked for soft tissue (minimum 2 mm thick) interposed between the torcula and the occipital squama on midsagittal T1 and T2 images; we recorded the maximal diameters and outcome.


RESULTS
Of 2,283 the children who had brain MRIs during the study period, 291 (12.7%, 95% confidence interval [CI] 0.11, 0.14) presented with a torcular pseudomass (median age 4 months, range 0 days to 35 months, 56% male). MRI features were the same in all of these children: T1 isointensity and T2 hyperintensity to the cerebral cortex, facilitated diffusion on diffusion-weighted imaging and apparent diffusion coefficient maps, and contrast enhancement. The median diameters were: anteroposterior, 5.8 mm; transverse, 10.5 mm; cranio-caudal, 20.6 mm. Follow-up MRI was available in 34.7% (95% CI: 0.20, 0.40) of the children; median follow-up time was 18 months. Among these children, 35.6% (95% CI: 0.26, 0.45) had total involution, 52.5% (95% CI: 0.26, 0.62) had partial involution and 4.1% (95% CI: 0.05, 0.18) showed stability.


CONCLUSIONS
Redundant soft tissue in the torcular region, or torcular pseudomass, is not an infrequent finding in infants and young children. It should be considered a physiological tissue, reflecting the postnatal developmental process of the brain and cranial vault, without the need for further investigation or follow-up imaging studies.
Department of Neuroradiology, Centro Hospitalar de São João, Alameda Prof. Hernâni Monteiro, 4200-319, Oporto, Portugal. lfvsampaio@sapo.pt.
Luísa
http://orcid.org/0000-0002-6775-470X
L
Sampaio
Neuroradiology Unit, Istituto Giannina Gaslini, Genoa, Italy.
Giovanni
G
Morana
Neuroradiology Unit, Istituto Giannina Gaslini, Genoa, Italy.
Mariasavina
M
Severino
Neuroradiology Unit, Istituto Giannina Gaslini, Genoa, Italy.
Domenico
D
Tortora
Neuropediatric Unit, Centro Hospitalar de São João, Oporto, Portugal.
Miguel
M
Leão
Neuroradiology Unit, Istituto Giannina Gaslini, Genoa, Italy.
Andrea
A
Rossi
D001921:Brain / Q000002:abnormalities* / Q000000981:diagnostic imaging*; D002675:Child, Preschool; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D033162:Incidental Findings; D007223:Infant; D007231:Infant, Newborn; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D012189:Retrospective Studies
Children; Development; Dura mater; Incidental findings; Infants; Magnetic resonance imaging; Occipital bone; Pitfall; Posterior fossa