Infantile myofibromatosis

Definition

Infantile myofibromatosis, or IM, is a rare tumor that grows in the skin, muscles, bones, and sometimes in the organs of the chest or abdomen. IM tumors are benign, which means they are not cancer and do not spread to other parts of the body. But these tumors may grow large and damage nearby organs.

Epidemiology

• IM is found at birth in about 1 out of 150,000 babies.
• Some cases of IM may not be diagnosed or correctly diagnosed.
• For this reason, IM may be more common than we think.
• It is most common in babies and young children.
• Over 90% of IM cases occur in children under 2 years old.

Cause

• Most of these tumors are sporadic and isolated.
• Rare familial cases of IM have been described and 2 genes have been identified as disease causing: PDGFRB and NOTCH3 which encode PDGFRB and NOTCH3 respectively.
• PDGFRB is a tyrosine kinase receptor for platelet derived growth factors which are mitogens for cells of mesenchymal origin.
• PDGFRB expression is up regulated by NOTCH3.
• This suggests that genetic defects in the 2 genes are involved in the same mechanism.

Inheritance

IM is mostly isolated and sporadic. In cases of familial and multifocal lesions, IM can be inherited as an autosomal recessive or dominant trait (incomplete penetrance and variable expressivity).

Signs and symptoms

• Infantile myofibromatosis (IM) presents at birth or develops shortly thereafter, with 90% of cases occurring before the age of 2 years.
• IM is characterized by solitary or multiple nodules that are firm, flesh-colored to purple (myofibroma), and usually painless (except in case of compression of adjacent nerves).
• Tumors are located in the skin, subcutaneous tissue, striated muscles and in exceptional cases, visceral organs or bones.
• There are 4 patterns of clinical presentation: solitary (single lesion affecting the skin and/or muscles in the head, neck, or trunk (75% cases)); congenital multiple (multicentric limited to skin and muscles); congenital multiple with single visceral involvement; and congenital multiple with multiple visceral involvement (multiple lesions of skin and/or muscles, bones, lungs, heart and gastrointestinal tract).
• Rarely, prenatal diagnosis could be evoked.

Clinical description

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed.

80%-99% of people have these symptoms

• Abnormality of the [[metaphysis](Abnormality of the wide portion of a long bone)
• Abnormality of the musculature(Muscular abnormality)
• Bone cyst(Bone cysts)
• Neoplasm of the skin(Skin tumors)
• Subcutaneous nodule(Firm lump under the skin)

30%-79% of people have these symptoms

• Abnormal hair morphology(Abnormality of the hair)
• Abnormal skull morphology(Abnormality of the skull)
• Abnormal thorax morphology(Abnormality of the chest)
• Chondrocalcinosis(Calcium deposits in joints)
• Gingival fibromatosis
• Neoplasm of the lung(Lung tumor)

5%-29% of people have these symptoms

• Abnormal sacrum morphology
• Abnormality of the eye(Abnormal eye)
• Abnormality of the kidney(Abnormal kidney)
• Benign neoplasm of the central nervous system
• Hemiplegia/hemiparesis(Paralysis or weakness of one side of body)
• Hypercalcemia(High blood calcium levels)
• Intestinal obstruction(Bowel obstruction)
• Irregular hyperpigmentation
• Limitation of joint mobility(Decreased joint mobility)
• Neoplasm of the pancreas(Cancer of the pancreas)
• Osteolysis(Breakdown of bone)
• Skin ulcer(Open skin sore)
• Tracheoesophageal fistula

Diagnosis

• Most babies with IM have purple-colored or skin-colored growths on their skin.
• But when the tumors are in the muscles or organs, symptoms may be different.
• Doctors usually find IM at birth when they examine the baby, but other tests may be done, too.

Imaging: If your child has symptoms of IM, your doctor will use scans such as ultrasound, MRI, or CT to see where the tumor is and how big it is. Biopsy: To check if the tumor is IM, your doctor will do a biopsy, taking a small sample of the tumor with a needle. An expert, called a pathologist, will study cells from the sample under the microscope and run other tests to see what kind of tumor it is.

Treatment

Treatment for each child will be unique. You should take your child to an expert in IM treatment to decide the best approach for their tumor. Watch and wait:

• In some cases, the tumor grows very slowly, or even shrinks without any treatment.
• In this case it may be safest for your doctor to check your child’s tumor often without treating it.

Surgery: In cases where the tumor is growing in or near the organs, surgery is the main treatment to remove the tumor and prevent damage to the organs. Chemotherapy: When surgery is not possible or does not work, chemotherapy may be used to treat IM.

Prognosis

• In the majority of cases, which lack visceral involvement, prognosis is excellent and spontaneous regression is often observed.
• On the other hand, the presence of visceral lesions is associated with a significantly poor outcome and a mortality rate of up to 70%, in the absence of therapy.
• Death is generally related to organ compression and cardiopulmonary and gastrointestinal involvement.

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NIH genetic and rare disease info

• NIH info on Infantile myofibromatosis

Infantile myofibromatosis is a rare disease.

Infantile myofibromatosis Resources
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