An unusual extra-axial hypodense lesion mimicking a chronic subdural haematoma
A 59-year-old man was found lying on the road with multiple facial and scalp lacerations well past midnight. He was assumed to have been involved in a road traffic accident and taken to hospital. At admission he was drowsy, disoriented but obeying verbal commands with a Glasgow coma scale (GCS) of E3V4M6. Computed tomography (CT) scan showed a thin hypo-dense extra-axial lesion in the left frontal region without mass effect and midline shift []. Patient was treated conservatively but was slowly deteriorating. A repeat CT scan [] showed some increase in the size of the hypodense lesion, so the attending surgeon decided to perform a frontoparietal craniectomy. During surgery no haematoma was seen but reddish thick fleshy tissue was seen. The trainee surgeon who operated unfortunately closed the incision without obtaining any biopsy. As there was no improvement, patient was taken to another centre where he was treated conservatively including steroids. The patient slowly improved, he was discharged, the steroids were made oral and tapered over one month.\nThe patient was brought to our centre, six weeks later with spikes of high fever. During inter-rogation it was understood that the patient has been slowly deteriorating a few days after discharge. At admission he was febrile, drowsy, GCS E2V2M5. CT scan showed a hypodense extra-axial lesion in the left fronto-temporal region with mass effect and midline shift [] with some enhancement on contrast CT. An incidental type 1 sylvian arachnoid cyst was also noticed on the right side. Magnetic resonance imaging (MRI) showed an isodense to hypo-dense lesion extra-axial lesion with a rim of cerebrospinal fluid (CSF) below [Figures and ]. The brain was seen fungating through the craniectomy site. An enplaque meningioma or an organized subdural haematoma was considered and surgery was planned.\nPatient underwent left front otemperoparietal craniotomy, during surgery there was a reddish fleshy vascular lesion just under the bone flap. Biopsy de-compression of the lesion was done. Patient was continued on steroids and improved dramatically only to deteriorate with features of increased intra-cranial pressure and papilloedema when steroids were tapered. The histo-pathology was Non-Hodgkin's lymphoma. Immuno histo-chemistry stains were positive for Cytokeratin and Leucocyte Common Antigen. The B-cell markers CD20 and CD79a were positive. Glial fibrillary acidic protein (GFAP) and Vimentin stains were negative. The Ki67 index was 8-10%. The blastic markers CD99 and Tdt were positive in focal areas. Biopsy obtained from brain tissue was reported normal. An extensive search for the primary including detailed clinical assessment, CT scans of abdomen and chest and bone marrow analysis were done but all these were negative. Immune status compromise and HIV were ruled out. The patient was referred to the oncologist but unfortunately deteriorated and died without the radio-therapy being completed.\nWhen the patient was with us he had a small swelling in the forehead which was reddish and firm and was attributed to the fall he had just before admission. During craniotomy a biopsy was taken from this site also and was suggestive of Non-Hodgkin's lymphoma.