A case of brain abscess mimicking cystic brain tumor and showing intraoperative 5-aminolevulinic acid fluorescence: case report .

Intraoperative fluorescence diagnostics is proved highly sensitive and specific for surgery of highly malignant brain gliomas, meningiomas and metastases. The greatest capability of accumulating 5-ALA was found in oligodendrogliomas, piloid astrocytomas and gliomas with cystic components. In some cases, making the differential diagnosis between a cerebral cystic tumor and a brain abscess can be difficult due to the similarity of clinical and neuroimaging data. A 37 year old male was hospitalized in a local neurological hospital. On admission, he presented with headaches, nausea, episodic vomiting, and weakness in the left extremities. In the last few months the patient suffered from recurrent episods of sinusitis. Contrast-enhanced brain CT scans revealed a right parietal lobe lesion of irregular shape (70x35 mm) with perilesional contrast enhancement. Contrast-enhanced MRI showed a mass lesion, which was hypointense on T1 with a marked contrast accumulation at the periphery. To the differential diagnosis between the suspected abscess and malignant tumor, we used the method of intraoperative metabolic navigation with 5-ALA. To relive the severe tension of the brain tissue, a ultrasound-guided cyst puncture was carried out. As a result, a thick yellow purulent discharge (~30 mL) was drained. Microbiological analysis of cyst contents revealed the presence of the pathogenic Streptococcus alactolyticus in the abscess’s content. The 5-ALA-induced fluorescence can be successfully used in neurosurgery for the differential diagnosis between a intracerebral tumor cyst and an abscess in the brain.