Female, 11 years old, with arachnoid cyst, presenting with recurrence of dizziness, assess for changes. A nonenhancing extra-axial cystic lesion is demonstrated interposed between the left frontal lobe and calvarium. This lesion continues to measure approximately 32 x 27 mm and shows no significant change in size.Newly seen on this examination is a vague, 5 mm focus of soft tissue which appears to be situated at the most dependent portion of the cyst given supine positioning of the patient (see image 11 series 10 and image 11 series 8). This structure is not discretely visualized on the prior examinations, though this could reflect differences in technique.As before, no part of the cystic lesion enhances. The cyst exerts mass effect upon the adjacent left frontal lobe parenchyma but without pathologic parenchymal signal abnormality. The remainder of the examination is within normal limits.
1.No significant change in the overall size of an extra-axial cystic lesion along the left frontal lobe.2.Newly visualized on this examination is a small quantity of nonenhancing ill-defined soft tissue which appears to be layering in the most dependent portion of the cyst given supine positioning. Although this tissue was not clearly evident on prior exams, differences in technique may have prevented its identification. 3.Given that this tissue is nonenhancing and located dependently, it may simply represent a small quantity of layering debris. The possibility of a growing nodule is considered less likely at this point. If further imaging evaluation is warranted, repeat imaging could be considered with sequences obtained in prone or lateral decubitus positions in an attempt to demonstrate mobility of this tissue within the cyst.