Imaging Spectrum of Neurological Manifestations of Hemophagocytic Lymphohistiocytosis in Pediatrics: A Case Series.

Hemophagocytic lymphohistiocytosis (HLH) is an uncommon condition, which can result either from a primary genetic abnormality affecting children or secondary to various conditions like malignancy or infection predominantly in adults. HLH is associated with immune dysregulation, resulting in an uncontrolled overproduction and infiltration of lymphocytes and histiocytes. The infiltration predominantly involves liver, spleen, lymph nodes, and central nervous system. Neuroimaging features on magnetic resonance imaging are highly nonspecific and variable. The most typical findings include periventricular white matter hyperintensities and diffuse atrophy. Ring or nodular enhancing or nonenhancing focal parenchymal lesions may be seen. Here, we present three pediatric cases of primary HLH with a wide spectrum of imaging findings involving cerebral and cerebellar cortex, white matter, deep gray matter, and brain stem. The findings in these patients range from small nonenhancing hemorrhagic lesions and enhancing small lesions to ill-defined mass with mass effect and midline shift. Lesions in deep gray matter including thalamus, basal ganglia, and also brain stem in HLH are rarely described in literature. Early diagnosis of HLH and timely management can improve the course of the disease.