Recurrent squamous cell carcinoma of the scalp, status post treatment, with new intracranial abnormalities depicted on CT. There are postoperative findings related to left occipital craniectomy and skin flap reconstruction, where there is a complex fluid collection measuring 5 cm in length deep to the inferior aspect of the skin flap overlying the left cerebellar hemisphere. There is diffuse stranding and enhancement of the overlying subcutaneous tissues and non-specific ill-defined soft tissue along the surgical margins. There regional pachymeningeal thickening and enhancement, as well as lack of left transverse sinus opacification. In addition, there is thick enhancing tissue overlying the dura in portions of the surgical bed, measuring up to 15 mm in thickness along the inferior surgical margin. There are several rim-enhancing fluid collections with restricted diffusion measuring up to approximately 20 mm and extensive surrounding vasogenic edema in the left occipital lobe and left cerebellum, where there are also patchy areas of susceptibility effect. There is associated effacement of the fourth ventricle and distortion of the brainstem and mild prominence of the third and lateral ventricles. There are small foci of high T2 signal in the right corona radiata and left thalamus superimposed on scattered foci of T2 hyperintensity in the cerebral white matter. There is fluid within the left mastoid air cells. There are bilateral lens implants. There is a left maxillary sinus retention cyst.
1. Postoperative findings related to left occipital craniectomy and skin flap reconstruction, with a new collection in the resection bed overlying the posterior fossa dura, increased dural thickening, and overlying subcutaneous fat stranding may represent abscess with pachymeningitis and cellulitis, with thrombosis of the left transverse sinus Superimposed recurrent tumor along the dura in the surgical bed is also a likely consideration, particularly given the history of positive margins at the prior resection. MRI is recommended for further evaluation.2. New hypoattenuation and swelling in the left occipital lobe and cerebellum may represent cerebritis and abscess formation perhaps with superimposed areas of neoplasm in areas closer to the overlying dura, with what may represent blood products in the inferior left cerebellar hemisphere and mild obstructive hydrocephalus.3. New fluid in the left mastoid air cells may represent mastoiditis.