Introduction: Patients with acute encephalopathy and cystic brain lesions often require ICU admission for neurologic monitoring. Neurocysticercosis is the most common cause, but in non-endemic regions metastatic disease must also be considered. Delays in diagnosis may worsen outcomes, while empiric antiparasitic therapy carries risks of inflammation and seizures. Description: A 40-year-old woman with bipolar disorder and cannabis use presented with abdominal pain, then developed bilious emesis, headache, ataxia, and confusion. She became lethargic and unarousable, requiring MICU transfer. Initial labs including blood count, renal and liver panels were unremarkable. CT head showed cystic masses with calcifications and edema compressing ventricles. MRI confirmed rim-enhancing lesions with midline shift. Initial impression favored neurocysticercosis. She was started on dexamethasone and levetiracetam, while antiparasitic therapy was deferred due to hyperinflammation risk. Neurosurgery deferred brain biopsy and recommended systemic workup. Infectious testing, including HIV, syphilis, cysticercosis, echinococcus, toxocara, strongyloides, cryptococcus antibodies, and viral PCRs was negative. CSF from a lumbar puncture (OP 30.2 cm) was acellular with normal protein and glucose; cytology was negative. Tumor markers showed elevated CEA (9.4) with normal CA-125 and CA 19-9. CT chest revealed necrotic mediastinal and hilar lymph nodes without pulmonary mass. CT abdomen showed a left adnexal cystic lesion. Gynecology noted the CEA elevation was nonspecific and that adnexal biopsy would be low yield, recommending mediastinal node biopsy. Pulmonology performed EBUS node biopsy, which revealed malignant small cells. Immunohistochemistry confirmed small cell neuroendocrine carcinoma. Discussion: This case shows how small cell carcinoma with cystic brain metastases can mimic neurocysticercosis, causing ICU admission for encephalopathy. The overlap of calcifications, negative infectious workup, nondiagnostic CSF, and absence of a lung mass complicated diagnosis. For intensivists, lessons are to keep metastasis on the differential for cystic brain lesions, consider additional imaging for primary neoplasms, recognize limits of CSF cytology, and pursue tissue diagnosis with multidisciplinary input before empiric therapy.
Ganesh et al. (Sun,) studied this question.