Rothmund-Thomson syndrome (RTS), is a rare autosomal recessive disorder, characterized by: skin photosensitivity, poikiloderma, sparse hair, sparse eyebrows/lashes, short stature, skeletal abnormalities, cataracts, and an increased risk of malignancy. Skeletal abnormalities include: dysplasia, absent or malformed bones, such as absent radii, osteopenia, and delayed bone formation. RTS is thought to result from chromosomal instability, and children with RTS are at risk of cancer. Reported cancers in children with RTS include: basal cell carcinoma, squamous cell carcinoma of the skin and osteosarcoma of bone. We report an 11 year-old boy, who presented to our institution with poikilodermatous skin change with telangiectasia and hyperpigmentation, absence of radius and thumb, and the development of osteosarcoma of the left tibia. The patient is now receiving supportive care and is receiving maintenance chemotherapy after surgery for osteosarcoma.