Vertebral Langerhans cell histiocytosis, formerly called Histiocytosis X, is rarely seen in adults: a systematic non-quantitative review of the literature yielded only 27 cases. Vertebra plana is often associated in children, but this is not a feature in the adult population. The authors report the case of a 29-year-old woman with a two-month history of lumbar pain. Osteolysis of the right pedicle of L2 was noted on CT and MRI. Transpedicular curettage and fusion L1L3 were performed. Histopathological examination revealed Langerhans cell histiocytosis. Although rare, Langerhans cell histiocytosis should be included in the differential diagnosis of the solitary lytic vertebral lesion in the adult. Good results have been reported, in the absence of systemic manifestations, with the most conservative approach possible.