MRI and Histopathologic Classification of Langerhans Cell Histiocytosis

Objective: The purpose of the study was to determine the stage of magnetic resonance images (MRI) of Langerhans cell histiocytosis (LCH). Materials and Methods: The MR images of 16 patients with a histopathologically proven diagnosis of LCH by curettage biopsy were analyzed retrospectively. There were 9 female and 7 male patients, age range 1-36 years, mean age 8.7 years. Lesions were located in the humerus (n=5), the femur (n=4), the pelvic ilium (n=3), the tibia (n=2), the scapula (n=1), and the metacarpal (n=1). We classified ‘type A’ as full hypercellularity lesion, ‘type B’ as peripheral hypercellularity and central fibrosis, and ‘type C’ as reduced cellularity on MRI of LCH. Histopathologic evolution of LCH comprised four different phases. Results: Four of 16 patients, who were reconfirmed to the first incipient phase of LCH histopathologically, revealed as one ‘type A’, two ‘type A and B’, and one ‘type B’. Eight patients with the second phase revealed seven ‘type B’ and one ‘type B and C’ on the MRI. One patient with the third phase revealed ‘type B’. Three patients with the last phase revealed all ‘type C’. The MRI findings are well correlated with the histopathologic findings of LCH.