paraneoplastic neurologic disorders ( pnd ) are a heterogeneous group of neurologic disorders associated with systemic cancer and caused by mechanisms other than metastases , metabolic and nutritional deficits , infections , coagulopathy , or side effects of cancer treatment . these syndromes may affect any part of the nervous system from the cerebral cortex to the neuromuscular junction and muscle , either damaging one or multiple areas . multiple malignancies are associated with paraneoplastic disorders like bronchial carcinoma , typically small cell carcinoma of the lung , testicular carcinoma , carcinoma of breast , immature teratoma of ovaries , etc . secondly , it is the first case describing features of paraneoplastic encephalitis in a case of astrocytoma with histolopathological evidence of both . a 55-year - old gentleman presented with memory lapses , insidious onset giddiness , gait disturbances , and imbalance since 6 months with a few episodes of convulsions . his first mri brain revealed two focal mass lesions in the right temporal and occipital lobes with multiple asymmetrical focal non - enhancing cortical hyperintensities involving bilateral temporal and fronto - parietal lobes . patient was treated with steroids . no antibacterial / antituberculous treatment ( att ) was started . follow - up second mri brain revealed increase in size of lesions in the right temporo - occipital lobes . follow - up third mri brain after 2 months of starting att showed persistent lesions . steroids were added to att ; however , patient had an episode of convulsion 1 month after his last mri study . his subsequent mri brain with mr spectroscopy was performed at our center . t2-weighted coronal images and fluid - attenuated inversion recovery ( flair ) axial images revealed two well - defined focal mass lesions in the right postero - medial temporal lobe and occipital lobe without any perilesional edema [ figure 1a and b ] . diffusion - weighted images ( dwi ) revealed no significant restriction of diffusion in the mass lesions [ figure 1c and d ] . post - contrast study revealed heterogeneous enhancement in the lesions [ figure 2a and b ] . mr spectroscopy revealed mild elevation of choline in the lesions , with choline to creatinine ratio in the range of 1.3 - 1.9 [ figure 2c ] . there was mild reduction in n - acetylaspartate ( naa , with choline to naa ratio in the range of 1.2 - 1.5 . there was mild elevation of choline and mildly elevated choline to creatine ratio ( 1.1 ) beyond the apparent margins of the lesion ; however , choline to naa ratio was maintained . flair axial image showing two well - defined focal mass lesions in the right temporal and occipital lobes ( a and b ) . dwi showing restriction of diffusion in the wall of the lesions in the right temporal / occipital lobe ( c and d ) ( a - c ) post - contrast t1 sagittal image shows heterogeneous enhancement of lesions in the right temporal and occipital lobes ( a and b ) . multivoxel intermediate te mr spectroscopywith mild elevation of choline in mass lesions , with choline to creatine ratio range is 1.3 - 1.9 ( c ) also noted were multiple focal asymmetrical areas of altered signal intensities in bilateral hippocampi , dorsal thalami , and cingulate gyri [ figure 3a and b ] . there was no abnormal enhancement on post - contrast study [ figure 3c and d ] . flair and t2w images show multiple focal hyperintensities in bilateral hippocampi , dorsal thalami , and cingulate gyri ( a and b ) , no enhancement was seen on post - contrast study in hippocampi and affected cortices ( c and d ) . multivoxel intermediate te mr spectroscopy shows normal choline peak ( e ) spectroscopy of these lesions showed normal spectral pattern [ figure 3e ] . in view of the imaging findings and spectroscopy data , possibility of intracranial metastases with paraneoplastic encephalitis was raised . subsequently , patient underwent whole - body positron emission tomography ( pet ) study which revealed focal fluorodeoxyglucose ( fdg ) avidity only in two intracranial mass lesions detected on mri in the right temporo - occipital lobes without any fdg avid lesion in the rest of the body [ figure 4a and b ] . pet ct showing avid fdg uptake in intracranial masses and no abnormal fdg avid activity in the rest of the body ( a and b ) patient underwent surgery for the excision of sols . mass lesion histopathology revealed pleomorphic astrocytes with interspersed proliferated blood vessels having heaped up endothelial cells ( glomeruloid structures ) [ figure 5a ] . immunohistochemistry also showed glial fibrillary acidic protein ( gfap ) positivity in the tumor cells [ figure 5c ] . 200 h and e and immunohistochemistry slide shows multiple neoplastic astrocytes with high mitotic index ( a - d ) . h and e slide shows reactive gliosis with interstitial and perivascular infiltrates of lymphocytes , a feature of paraneoplastic encephalitis ( d ) biopsy of cortical area showing non - neoplastic signal abnormality revealed reactive gliosis with interstitial and perivascular infiltrates of lymphocytes , a feature of paraneoplastic encephalitis [ figure 5d ] . no paraneoplastic antibody ( ab ) screening was done in our patient due to financial constraints . follow - up postoperative and postradiotherapy mri done 6 months after surgery showed significant resolution of non - neoplastic cortical lesions , possibly representing regression of paraneoplastic encephalitis after removal of the primary [ figure 6 ] . flair axial and t2w coronal images in follow - up mri done after 6 months reveal significant decrease in cortical hyperintensity in bilateral cigulate gyri when compared with preoperative initial mri images ( c and d ) pnd cover a wide range of diseases and involve both central nervous system ( cns ) and peripheral nervous system . pnd comprise several diseases such as paraneoplastic cerebellar degeneration ( pcd ) , limbic encephalitis ( le ) , paraneoplastic encephalomyelitis ( pem ) , brainstem encephalitis , opsomyoclonus syndrome , in addition to other even less frequently occurring entities . le is now regarded as a more frequent disorder than it was earlier thought to be , as a result of improved neuroimaging and ability to detect associated abs . in the past few decades these encompass the classical  onconeuronal  abs such as hu , yo , ri , and others , and , in addition , the abs toward either ion channels or surface antigens like ampa , gabab , and nmda receptors . autoantibodies not to neurons , but to glial cells , i.e. anti - glial nuclear antibody , have also been detected in patients with paraneoplastic le associated with lung cancer . common malignancies associated with le are small cell lung cancer , thymoma , germ cell tumors of the testis , breast cancer , and ovarian teratoma . however , astrocytoma is not listed as a possible cause of le . there is a case report of spinal cord astrocytomas with possible paraneoplastic encephalitis ; however , neither it had histological confirmation nor were the immunological markers found positive . le is characterized by personality changes , irritability , depression , seizures , confusion , loss of recent memory , and dementia . the symptoms are due to dysfunction of the limbic system ( hippocampus , amygdala , hypothalamus , insular and cingulated cortex ) . the diagnosis of le is often difficult clinically because le may precede detection of tumor and in patients with known malignancy , similar symptoms can be attributed to many other malignancy - related complications , including brain metastases , metabolic encephalopathies , infections ( especially with herpes simplex encephalitis ) and toxic encephalopathy secondary to the side effects of chemotherapeutic agents , etc . imaging plays a crucial role in such circumstances . mr imaging can aid in establishing the diagnosis of paraneoplastic le , especially in those cases in which no characterized antineuronal antibody can be detected in serum or csf . t2-weighted imaging and flair imaging techniques are useful . gultekin et al . mentioned that typical mri findings of paraneoplastic encephalitis include unilateral or bilateral mesial temporal lobe abnormalities that are best seen on flair and t2-weighted images . on t1 sequences , the temporal - limbic regions may be hypointense and atrophic , and may sometimes enhance with contrast injection . they also mentioned that 64% of their patients with paraneoplastic encephalopathy had abnormal mri studies , which showed the changes indicated above in 89% of the cases . contrast enhancement is very rare with only a few cases reported . in our patient , imaging differential of seizure - induced changes in the presence of intracranial sols was excluded . there was no resolution or interval change in cortical abnormalities on sequential mris when compared to seizure - induced cortical changes which show resolution on follow - up mri . presence of mass lesions could not be explained with herpes encephalitis . in cases of glial tumors , sometimes differentiation between malignant tumors , including dissemination or gliomatosis cerebri and paraneoplastic le , becomes difficult . nagata et al . reported a patient with secondary gliomatosis cerebri that mimicked the clinico - radiological features of le . thus , the possibility of gliomatosis cerebri in the bilateral temporal lobes could not be fully excluded in their case . furthermore , a case with bilateral temporal lobe glioma presenting as paraneoplastic le had been reported by deramecourt et al . to the best of our knowledge , this case proves to be the first of its kind where intracranial astrocytic neoplasm is associated with paraneoplastic encephalitis . in conclusion , possibility of paraneoplastic le should be thought of in cases of astrocytomas when intracranial findings can not be explained by tumoral invasion . differences in the imaging appearances and spectroscopy data between tumor and other areas of cortical signal abnormality may aid in suspecting this rare entity .
paraneoplastic encephalitis is a multifocal inflammatory disorder of the central nervous system ( cns ) that is associated with remote neoplasias . 
 the most common malignancy associated with it is bronchial carcinoma , typically small cell carcinoma of lung . 
 it has never been described in association with intracranial neoplasm . 
 we present and discuss the clinical , radiological , and histopathological findings of paraneoplastic encephalitis with intracranial space - occupying lesions ( sols ) in a 55-year - old man . 
 he was thoroughly investigated and biopsy revealed presence of astrocytoma with changes of paraneoplastic encephalitis .