Background: The brain is a frequent site of metastases in small-cell lung cancer. Symptoms of cerebral involvement are headache, disorientation, nausea/vomiting and seizures.
Case: A man with small-cell lung cancer developed a human herpesvirus 6 (HHV-6) meningoencephalitis with neurological symptoms that simulated brain involvement from the lung cancer. HHV-6 is a T cell lymphotropic virus which may be pathogenic in the immunocompromised host. HHV-6 remains latent after the first infection, and when the immune system is compromised it can reactivate. The treatment of HHV-6 infection is highly specific and the drugs recommended are the two antivirals, ganciclovir or foscarnet.
Conclusion: In cancer patients neurologic symptoms are usually due to brain metastases. This case shows that in a cancer patient any aspecific neurologic symptom should be carefully evaluated in order to exclude a non-oncologic cause. This statement is particularly true if the therapies for the oncological and neurological diseases are effective.