Final answer:
Fibroxanthoma is a benign tumor that commonly occurs in the long bones of children and adolescents. It is made up of fibrous connective tissue and is usually asymptomatic. In contrast, fibrodysplasia ossificans progressiva is a rare genetic disorder that causes progressive conversion of connective tissue into bone.
Step-by-step explanation:
Fibroxanthoma is a condition also known as nonossifying fibroma (NOF). It is a benign tumor that commonly occurs in the long bones of children and adolescents.
Fibroxanthomas/NOFs are made up of fibrous connective tissue and appear as well-defined, oval-shaped masses on imaging scans. They are usually asymptomatic and do not require treatment unless they cause pain, fracture, or interfere with bone growth.
In comparison, fibrodysplasia ossificans progressiva (FOP) is a rare genetic disorder that causes connective tissue to turn into bone progressively, leading to restricted movement and bone-like growths in soft tissues.