Stone girl disease in children symptoms causes and treatment

Have you ever noticed that your child has unusual joint stiffness or hard lumps in the muscles? Or maybe they were born with deformities in the thumbs or toes? These could be signs of Fibrodysplasia Ossificans Progressiva (FOP), also known as Stone Man Syndrome, a very rare condition where muscles, ligaments, and tendons gradually turn into bone.This disease doesn’t just affect a child’s movement—it can also impact their overall growth and general health. In this article, we’ll walk you through the causes, symptoms, stages, diagnosis, and risks of FOP, along with practical tips for parents from Dalily Medical on how to care for and protect their child.

Is Fibrodysplasia Ossificans Progressiva (FOP) in Children Hereditary?

Most cases occur due to a new genetic mutation in the ACVR1 gene.

Rarely, the disease is inherited in an autosomal dominant pattern, meaning that only one copy of the altered gene is enough to cause the condition.

In most cases, children with FOP are born to genetically healthy parents.

When Do Symptoms of FOP Appear in Children?

Deformities in the thumbs or toes are usually visible at birth.
Progressive ossification (muscles turning into bone) typically begins in early childhood, usually between ages 2 and 6.

Symptoms of FOP in Children

Malformations of thumbs and toes.
Hard lumps or swellings in the muscles that gradually turn into bone.
Progressive restriction of movement, making it difficult to walk or perform daily activities.
Pain or stiffness in the joints.

Can FOP Be Cured?

Currently, there is no permanent cure for FOP.

Treatment mainly focuses on:

Relieving symptoms.
Slowing down ossification.
Maintaining the child’s quality of life.

Is Surgery Helpful in FOP?

Surgery is not a treatment for the disease itself.
It may only be used to correct complications or in emergency cases.
Any surgical procedure carries a high risk of new bone formation at the surgical site, so it should be avoided whenever possible.

Can Children with FOP Go to School?

Yes, with certain adjustments such as:

Providing mobility aids if needed.
Coordinating with teachers and physical therapists for easier participation.
Having an emergency plan in place for movement difficulties or pain.

How to Support a Child with FOP in Daily Life

Regular physical therapy sessions to preserve joint flexibility.
A healthy diet to support muscle and bone health.
Protecting the child from injuries and falls.
Psychological and social support to boost confidence and help with peer integration.

What is FOP in Children?

FOP (Fibrodysplasia Ossificans Progressiva) is an extremely rare genetic disorder in children that causes muscles and soft tissues to gradually turn into bone.
Over time, this leads to restricted joint mobility and severe movement limitations.

Causes of FOP in Children

Mutation in the ACVR1 gene
- The main cause of FOP is a mutation in the ACVR1 gene, which controls bone and soft tissue growth.
- The mutation triggers the formation of extra bone in abnormal places like muscles, ligaments, and tendons.
De novo (spontaneous) mutation
- Most cases appear spontaneously, with no family history.
- Parents are usually genetically healthy, but the child develops the mutation randomly.
Rare inherited cases
- In very rare instances, FOP can be inherited in an autosomal dominant pattern.
Not caused by lifestyle or environment
- Nutrition, environment, or lifestyle do not cause FOP.
- The cause is always linked to the ACVR1 gene mutation.

Types of FOP in Children

Classic FOP
- The most common type.
- Usually appears with toe or thumb deformities at birth.
- Ossification begins in the neck and shoulders and spreads to other parts of the body.
Atypical / Mild FOP
- Milder symptoms that may begin after the first year of life.
- Some joints or muscles remain unaffected for longer.
- Thumb and toe deformities may differ from the classic type.
Rare Acquired Variants
- Extremely rare.
- Appear after birth due to different ACVR1 mutations.
- Cause limited ossification and less severe progression.

Early Symptoms of FOP in Children

Finger and toe deformities
- Short or bent thumbs at birth.
- Possible deformities in the toes.
Hard lumps in muscles
- Firm swellings under the skin, often after minor injuries or without a clear cause.
- These lumps gradually turn into bone.
Movement difficulties
- Over time, joint flexibility decreases as muscles and tissues turn to bone.

Advanced Symptoms of FOP

Progressive ossification
- Muscles, ligaments, and tendons in the neck, shoulders, back, and large joints harden into bone.
- This makes walking and arm movement increasingly difficult.
Severe mobility restrictions
- Difficulty bending, sitting, or lifting the arms.
- Some joints may become completely immobile.
Abnormal bone and muscle growth
- Muscles shrink and weaken due to ossification.
- Bones may become fragile (osteoporosis risk).
Chronic pain
- Children may experience pain or stiffness in affected areas, especially after flare-ups or minor injuries.

Diagnosis of FOP in Children

Clinical examination
- Checking for thumb or toe deformities at birth.
- Assessing joint size and mobility.
- Observing firm swellings or lumps in early childhood.
Medical and family history
- Asking parents about:
  - When symptoms first appeared.
  - History of swelling or hard lumps.
  - Any similar cases in the family (most cases are new mutations, not inherited).
Laboratory tests
- No specific blood test for FOP.
- Tests may be performed to rule out other similar conditions.
- Occasionally, liver and kidney function tests are done if needed.

Surgery in Fibrodysplasia Ossificans Progressiva (FOP) in Children

Important Notes Before Any Surgery

Surgery is not a cure for the disease, as it does not stop the ossification process.
Any unnecessary surgical intervention may actually trigger additional bone formation at the surgical site.
Therefore, surgery is considered only in emergency cases or for severe complications.

Situations Where Surgery May Be Needed

Severe bone or joint deformities
- When deformities significantly limit movement or cause visible disability.
- Surgery may help improve mobility or appearance partially.
Fractures or bone-related issues
- Rarely, fractures may occur due to bone fragility.
- Sometimes surgical fixation or correction is required.
Life-threatening emergencies
- Such as breathing or circulatory problems.
- Surgical intervention is done only to save the child’s life.
Severely restricted joint function
- When joints are so stiff that daily activities become nearly impossible.
- Surgery aims to improve the child’s quality of life as much as possible.

Table: Surgical Indications, Risks, and Post-Operative Advice

Surgical Case	Reason for Surgery	Risks	Post-Operative Advice
Severe bone or joint deformities	Improve movement or appearance in case of major deformity	Additional bone formation at the surgical site, worsening ossification	Regular follow-up with an orthopedic specialist, physical therapy, anti-inflammatory medications if prescribed
Rare fractures or bone problems	Stabilization or correction of fractures due to fragile bones	Abnormal bone growth, pain, joint stiffness	Protect affected area, routine X-ray monitoring, light exercises under physiotherapist supervision
Emergency cases (breathing/circulation)	Correct life-threatening problems	Severe surgical complications, extra bone formation	Monitor lungs and heart, provide respiratory support if needed, manage pain and inflammation appropriately
Limited joint function correction	Improve ability to perform daily activities	Recurrent ossification at surgical site, chronic pain	Ongoing physiotherapy, mobility aids, strict adherence to medical follow-up

Key Notes for Parents and the Medical Team

Surgery is not a permanent solution, but it can help reduce complications and improve the child’s quality of life.
Any surgical procedure must be performed by a medical team experienced in FOP to minimize risks.
Post-operative care is critical: preventing injuries and reducing the chance of new bone growth at the surgical site.
Regular follow-up with orthopedic specialists and physiotherapists is essential to maintain maximum mobility and prevent worsening of the condition.