PLE is a rare neurological syndrome characterized by personality changes, irritability, depression, seizures, memory loss, and sometimes dementia. Common solid tumors such as SCLC, testicular teratoma, and breast cancer are well known to be associated with PLE. Although the exact pathophysiological link is not obvious, the presence of antineuronal antibodies has been documented in some cases. However, the lack of specificity and availability of these markers make testing for these antibodies less helpful for diagnosis. Where these markers are unavailable, brain imaging can be used to support the diagnosis in cases of progressive neurological deterioration. Our patient was initially suspected to have a tumor of the hypothalamus with associated cranial diabetes insipidus. We suggest that the initial appearance of a hyperdensity in the hypothalamus could be due to hyperemia secondary to hypothalamitis. This is supported by previous evidence on CT perfusion images that showed a focal increase in the cerebral blood flow and shortening of the mean transit time in the bilateral hippocampi and amygdalae in a patient with encephalitis [
5]. Bitemporal hypodensities on a noncontrast CT scan should always raise suspicion for encephalitis, and it is important to arrange an early MRI scan for further evaluation of such lesions. MRI can show unequivocal involvement of temporolimbic structures and helps to exclude other diagnoses [
6]. Although MRI is more sensitive than CT for the detection of inflammatory brain lesions because of the higher contrast resolution, CT is still valuable when used with other supporting clinical evidence in settings where other sophisticated scan techniques are not freely available [
7]. There are few reported cases of normal CT scans in patients with PLE, and precise epidemiological data are not available [
8,
9]. CT evidence of a central hyperdensity surrounded by a bitemporal hyperdensity is a valuable tool with which to identify possible PLE in resource-poor settings. The role of 2-deoxy-2-[F-18] fluoro-D-glucose-positron emission tomography imaging in the clinical management of paraneoplastic neurological syndrome is evolving and thus far has shown much better results than MRI [
10]. These investigations are less popular in resource-poor settings because of the lack of availability and higher cost. Hypothalamitis is a less established pathological entity. However, histological diagnosis is not practical because of the highly invasive nature of biopsy and the deep location of the hypothalamus. Several reported cases of diagnostic stereotactic biopsy have revealed inflammatory infiltrates mainly constituting lymphocytic inflammation [
11‐
13]. Based on these findings of a common histological pattern, we suggest that highly invasive biopsy has lower priority than imaging. Other than acute paraneoplastic hypothalamitis, another variety of hypothalamitis is relapsing autoimmune hypothalamitis [
14]. However, based on the present case and those described in the literature, we suggest that screening for a hidden malignancy should be an essential step in the initial evaluation of the patient. Another pathological entity that presents with cranial diabetes insipidus is infundibuloneurohypophysitis [
15,
16]. Radiological differentiation of pure hypothalamitis from infundibuloneurohypophysitis is rather difficult. Importantly, this demarcation is not essential for appropriate patient management.
In summary, this case report provides useful insights regarding the radiological pattern of limbic encephalitis in noncontrast CT, which may guide physicians in the early diagnosis and prompt management of PLE.