In most cases, an accurate diagnosis of Fibrodysplasia Ossificans Progressiva (FOP) can be made based on the patient's characteristic signs and symptoms of the disorder. Young children typically have malformed big toes and painful, tumour-like swellings on the head, neck, and/or back.
However, researchers believe that FOP is often misdiagnosed because it is a rare disease, affecting about one out of every two million people worldwide. Three most common misdiagnoses of FOP are Cancer, aggressive juvenile fibromatosis and progressive osseous heteroplasia. Experts estimate that the rate of misdiagnosis of FOP is arround 80% or higher.