Nodule on posterior scalp that has tripled in size over the last few months. There is a well-defined heterogenous nodular cystic lesion in the left temporoparietal scalp that measures up to 22 mm with internal patchy enhancement that dissipates over time, as well as scattered areas of susceptibility effect. There is an vessel in the underlying scalp that appears to penetrate the lesion. There are additional subcentimeter cystic lesions in the midline occipital scalp and right retroauricular scalp. The calvarium is intact. There is no evidence of intracranial hemorrhage, mass, or acute infarct. The brain parenchyma and pituitary gland appear unremarkable. There is no abnormal intracranial enhancement. The ventricles and basal cisterns are normal in size and configuration. There is no midline shift or herniation. The major cerebral flow voids are intact. The orbits are unremarkable.
The findings are indicative of a hemorrhagic epidermal inclusion or pilar cyst in the left temporoparietal scalp that measures up to 22 mm. Additional subcentimeter cystic lesions in the midline occipital scalp and right retroauricular scalp also likely represent inclusion or pilar cysts. 