Cerebral fat embolism following percutaneous lung biopsy

Clinical History

We present the case of a 65-year-old lady who underwent CT guided percutaneous biopsy of a mass in the right upper lung lobe. 24 hours after the procedure the patient collapsed, had a generalized seizure and developed focal neurological signs with decreased level of consciousness, requiring ITU admission.

Imaging Findings

Chest X-ray and PET-CT of the thorax show the right upper lobe hypermetabolic lung lesion (Fig. 1-2). This lesion was biopsied under CT guidance (Fig. 3). An urgent CT of the brain following collapse revealed gyriform hypodense areas in several of the right frontal lobe gyri. These hypodense regions measured -23 Hounsfield units in keeping with fat density (Fig. 4). No other abnormalities were seen. An MRI performed on the following day showed areas of gyriform restricted diffusion in the right frontal and parietal cortex corresponding to the areas of fat deposition seen on CT (Fig. 5). Much less prominent restricted diffusion was also seen on the left in a similar distribution. Corresponding areas of moderate high signal intensity were seen on the FLAIR sequence. MRA and MRV were unremarkable. A repeat CT carried out two weeks following the event was normal.

Discussion

Despite fat embolism syndrome (FES) being initially described in 1893, it remains a difficult diagnosis to clinch as it may present with different clinical syndromes [1]. FES most commonly occurs after long bone and pelvic fractures; however, it has also been associated with non-traumatic aetiologies like pancreatitis and osteomyelitis [2]. To date no reports exist of FES complicating percutaneous lung biopsy. FES has been classically described as presenting with a triad of hypoxaemia, neurological abnormalities and a characteristic petechial rash 24 to 72 hours after the original insult. The rash, however, only occurs in 20 to 50 per cent of cases and resolves within 5 to 7 days [3]. Diagnosis is clinical and is usually made when clinical signs occur in an appropriate clinical setting and no other alternative diagnosis exists. Radiology, however, can be used to corroborate the diagnosis. In cerebral fat embolism MRI of the brain has been described as showing high intensity T2/FLAIR signal and restricted diffusion on the diffusion weighted sequence. The latter should correlate with the degree of neurological impairment [4]. Computed Tomography of the chest usually shows areas of ground glass opacification with interlobar septal thickening and Ventilation/Perfusion scanning may show a mottled pattern of subsegmental perfusion defects with normal ventilation patterns [5, 6]. There is no specific treatment for this clinical syndrome and management is supportive until the patient recovers. Unlike our case (the patient suffered permanent neurological sequelae due to with a right sided cerebral insult), most patients who suffer from FES eventually make a full recovery.

Differential Diagnosis List

Final Diagnosis

Cerebral fat embolism following percutaneous lung biopsy (poorly differenciated adenocarcinoma)

URL:	https://www.eurorad.org/case/9972
DOI:	10.1594/EURORAD/CASE.9972
ISSN:	1563-4086