Clofarabine (CLO) monotherapy reportedly induces a better clinical response in some patients with refractory Langerhans cell histiocytosis (LCH). We successfully treated two patients with refractory multisystem LCH with CLO monotherapy after recurrence. We administered 23 courses of CLO monotherapy in patient 1 and 4 courses in patient 2. Both patients achieved a durable complete response with acceptable adverse effects of transient myelosuppression. CLO monotherapy is a better therapeutic option for high efficacy and feasibility than other combination chemotherapies or allogeneic hematopoietic stem cell transplantation for refractory LCH.

We report on a 12-year-old female who developed osteosarcoma with tuberous sclerosis. Clinical sequencing of osteosarcoma tissues identified a somatic mutation in the TP53 gene and a novel germline mutation in the TSC2 gene. Pathological analysis of osteosarcoma tissue revealed increased phosphorylation of S6, a downstream target in the mTOR pathway. This is the first reported detection of a germline TSC2 mutation and somatic TP53 mutation in osteosarcoma with tuberous sclerosis. This case is unique and suggestive of a TSC2-dependent genetic pathway through mTOR signaling and a second-hit model for oncogenesis.