Adult Hemophagocytic Lymphohistiocytosis (HLH) with Neurological Involvement: Diagnostic Complexities - A Case Report and Literature Review.

BACKGROUND Hemophagocytic lymphohistiocytosis (HLH) is a potentially fatal disease that is uncommon among adults. It is characterized by proinflammatory overactivity of the immune system. In infants it is usually hereditary, whereas in adults it is secondary to infection, malignancies, or autoimmune diseases. Clinical features include fever, hepatosplenomegaly, pancytopenia, lymphadenopathy, hypertriglyceridemia, hyperferritinemia, hemophagocytosis, and, rarely in adults, CNS involvement. CASE REPORT We report the case of a 54-year-old man, in whom HLH has been diagnosed, manifesting mainly as neurological signs - increasing spastic paraparesis with sphincter disorder. He had a fever of unestablished etiology for about 1 year. On brain and thoracic spinal cord MRI there were multiple disseminated focal lesions suspected of being demyelination. Neuromyelitis optica spectrum disorder (NMOSD) and multiple sclerosis were excluded. Treatment with dexamethasone, etoposide, cyclosporine A, and intrathecal methotrexate was used. After a temporary significant improvement in his clinical condition, the patient died 18 months after diagnosis. Our literature review found 37 cases of HLH with neurological symptoms. Only 3 of these cases (and only 1 of them similar to our case) involved clinical and imaging features of demyelinating disease, as in the present case. CONCLUSIONS HLH mimicking demyelinating disorders is rarely encountered clinically. In such a situation, making a diagnosis is extremely difficult and the initiation of appropriate treatment may be delayed, which significantly worsens the prognosis for patients. Increased clinical awareness of HLH should be present in the non-specific course of various diseases, including those with neurological symptoms of unclear origin.