Fibrodysplasia Ossificans Progressiva

Fibrodysplasia Ossificans Progressiva (FOP)

Signs and Symptoms
Diagnosis
Treatment

Signs and Symptoms

The hallmark symptom of fibrodysplasia ossificans progressiva (FOP) is a malformation of a newborn's big toe. This malformation, which is apparent at birth, consists of  a short big toe with an abnormal turning of the toe called a valgus deviation.

During early childhood, most of those with FOP form painful fibrous nodules, or tumor-like swellings, over the neck, back and shoulders. These nodules often develop after a child experiences some sort of trauma to the body, such as a bump or fall. Episodes also can occur without any warning or may not occur at all. In most cases, the nodules transform into bone during a process known as heterotopic ossification.

When the body starts to generate new bone, the patient usually experiences a painful flare-up. Tissue swelling, joint stiffness and serious discomfort can occur. Some may have a low-grade fever. Flare-ups can last as long as six to eight weeks. The disease then progresses along the trunk and limbs of the body. These lesions slowly replace the body's muscles with normal-looking bone.

Reviewed by health care specialists at UCSF Children's Hospital.
Last updated May 8, 2007