On 15/6, a representative from Children's Hospital of Ho Chi Minh City announced that a 12-year-old girl was admitted with restricted movement in her left hip after a minor fall while learning to ride a bicycle. Initially, she experienced swelling, numbness, and discomfort in her left buttock, followed by joint stiffness and difficulty walking. Over nearly two years, her condition worsened, with stiffness spreading to her spine, neck, and shoulders, severely impacting daily activities.

The case was difficult to identify because the girl did not have malformed big toes, a classic sign present in over 90% of individuals with Fibrodysplasia Ossificans Progressiva (FOP), an extremely rare genetic disease that causes muscles, ligaments, and soft tissues to gradually turn into bone.

Due to the absence of this sign, the patient was initially monitored with an undiagnosed condition. Surgery to release hip joint stiffness was even planned to improve mobility. However, after being transferred to Children's Hospital of Ho Chi Minh City for a comprehensive re-evaluation, doctors determined the surgery was not truly necessary and could potentially worsen the condition.

A computed tomography (CT) scan of the pelvic area revealed ossified tissue next to the greater trochanter of the left femur, but it was not directly connected to the underlying bone structure. This image suggested a group of rare diseases causing soft tissue ossification.

Given the atypical clinical presentation, the medical team decided to perform gene sequencing. The results showed the patient carried a pathogenic variant in the ACVR1 gene, confirming the diagnosis of fibrodysplasia ossificans progressiva – a disease with a prevalence of about one in two million people worldwide.

Gene sequencing for the patient. Photo: Quynh Tran

Following the diagnosis, doctors decided not to proceed with the previously planned surgery. Interventions that damage soft tissue, such as surgery, biopsy, or intramuscular injections, can trigger inflammatory responses in FOP patients, accelerating the ossification process.

Currently, treatment focuses on managing flare-ups with short-term corticosteroids or non-steroidal anti-inflammatory drugs, while maintaining motor function and minimizing injury risk. The patient also undergoes hearing screening due to the risk of hearing loss associated with middle ear damage.

Fibrodysplasia ossificans progressiva currently has no definitive cure. Children presenting with recurrent soft tissue swelling, subcutaneous fibrous masses, and progressive joint stiffness, especially after minor trauma, should be considered for this condition, even without malformed big toes.

If the disease is suspected, parents should avoid unnecessary interventions such as intramuscular injections, biopsies, vigorous massage, or excessive joint stretching. Early diagnosis can help limit complications, avoid high-risk interventions, and preserve the child's mobility.

Le Phuong