Bone xanthoma (syn.: bone braulosis, bone xanthopsia) is a rare skeletal disease of unknown etiology, manifested by focal deposits of mucin in the bones of the extremities. More often observed in older men. May be asymptomatic, but may manifest as spontaneous pain or limb deformity. Xanthoma tissue may turn out to be malignant, in which case a biopsy of the affected tissue will be necessary.