Only 10 percent of doctors have ever heard of fibrodysplasia ossificans progressiva

A new research study shows how common a medical misdiagnosis can be and how severely it can exacerbate a disease.

Focusing on a rare, genetic and disabling disease known as fibrodysplasia ossificans progressiva, or FOP, researchers designed the study as an examination of the frequency of misdiagnosis and the complications associated with it.

Their findings are reported in the November issue of the journal Pediatrics.

FOP is a disorder of connective tissue that ultimately results in massive bone formation across the body's major joints, eventually rendering movement impossible. The disorder affects one in two million people worldwide, and there are 200 known cases in the U.S.

The study found that FOP is misdiagnosed 87 percent of the time, takes an average of four years to be accurately diagnosed, and often is inaccurately identified as cancer. The inaccurate diagnoses have led to painful biopsies and incorrect treatments that in themselves often worsened the condition of the patient, speeding permanent loss of mobility.

"It is unfortunate that individuals afflicted with this rare disabling disease have suffered further serious problems due to incorrect diagnoses by their physicians," said Joseph Kitterman, MD, lead investigator and professor of pediatrics at the University of California, San Francisco.

In addition to Kitterman, the team included researchers from the University of Pennsylvania, the International FOP Association, and the University of California, Davis.

Based on study findings, the researchers estimate that only 10 percent of doctors have ever heard of FOP. Only eight percent of the 184 medical textbooks that they reviewed contained adequate descriptions of FOP.

An accurate diagnosis of the disease can be made based on the clinical findings of tumor-like swellings on the head, neck, back or shoulders in association with malformations of the great (big) toes, according to Kitterman. However, the study showed that physicians often misdiagnosed the condition because the patient was not fully examined or the physician was not aware of FOP.

The disease is distinguished by the unique characteristics of toe malformations and missing joints which are present at birth, but their significance is almost never appreciated, Kitterman noted.

"The irony here is that diagnosis of FOP has distinguishing features and is obvious just by asking a few simple questions," he said. "Instead, with misdiagnosis of this rare disease, the result was anxiety and pain for the patient."

The study found that patients often endured painful deep muscle biopsies and permanent complications due to misdiagnosis, with almost half reporting permanent loss of mobility that resulted from invasive procedures.

No condition other than FOP is associated with malformed toes and rapid tissue swellings during childhood, Kitterman said.

"FOP can look like cancer. Inspection of the toes, however, would instantly reveal a different disease," said co-investigator Frederick Kaplan, MD, an international FOP expert at the University of Pennsylvania and director of one of the few research centers in the world investigating the disease.

"The disease is easy to diagnose once the physician knows what to look for," he added.

The study findings showed that it took an average of six physicians to accurately diagnose FOP. Those consulted most frequently were orthopedic surgeons, pediatricians, general practitioners, oncologists, rheumatologists and internists.

The research team reviewed the experiences of 138 patients with FOP from around the world. The extremely high rate of misdiagnoses was worldwide, with cancer cited most often. Sixty-seven percent of the study patients had unnecessary invasive procedures, and 68 percent received inappropriate therapies.

The next steps in finding a cure for FOP are to define the metabolic pathways that influence the disease and identify the gene that causes it, according to the researchers.

In addition to Kitterman and Kaplan, the study team included Sharon Kantanie, MAT, of the International FOP Association, and David Rocke, PhD, of the University of California, Davis.