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Rhabdomyosarcoma (RMS or Rhabdo) is an aggressive and highly malignant form of cancer that forms in the soft tissues and is thought to arise from early skeletal muscle precursor cells. It can occur anywhere in the body but is most generally found in the structures of the head and neck, the urogenital tract, and the arms or legs but can also form in parts of the body without muscle, such as the bile duct, the prostate, or along the meninges, the membranes that line the skull and vertebral canal. While generally thought of as a childhood disease—a majority of cases are found in children and young adults—it is not uncommon to have adult patients diagnosed with Rhabdo as well.

Rhabdomyosarcoma is considered a rare cancer—with roughly 350 cases diagnosed in the US each year—although it is the most common soft-tissue sarcoma in children and adolescents under the age of 20. With so few cases to be seen, it is unusual for any pediatrician or primary care physician to see one, let alone a number of patients with this disease.

Rhabdomyosarcoma Presentations

Not only is Rhabdo a rare disease, but it presents itself differently in almost every case. For example:

  • A Mosquito Bite? — A first grader was being bathed by her father who noticed a small bump on her leg. It looked very much like a mosquito bite but it wasn’t mosquito season and something just ‘didn’t look right.’ He took her to the pediatrician, who could have easily said, ‘looks like a bug bite, let’s wait a few days to see what happens.’ But instead said that he was going to do an ultrasound and if he saw anything unusual, she was going to be sent for an immediate biopsy. The small, mosquito bite like bump was the very end of a tumor that grew the entire length of her calf muscle before it began to move outward.

  • A Stomach Bug? — A pre-schooler with headaches that only seemed to be relieved after he vomited. Pediatrician noted that the same thing happened 4 times in the past month, that the vomit was ‘foamy’ and not food, and recorded that the child’s temperature was normal. After a number of similar visits, the child was given a prescription for a medication that is designed to treat certain stomach and esophagus problems (such as acid reflux, ulcers). The headaches and vomiting continued for over a month at which time the pediatrician’s office recommended that he be brought to a children’s hospital. A CT scan indicated a diagnosis of hydrocephalus. He was then given an MRI which showed the presence of diffuse tumor along the meninges, consistent with a possible medulloblastoma or lymphoma. A surgical biopsy revealed that the tumor was Embryonal Rhabdomyosarcoma.

  • A Vericocele? A college freshman discovered that he had a lump on his testicle. After an examination by a urologist, he was told that it was possibly a vericocele (a conglomeration of veins that occur in the testicles) and that he should watch it for about three months and if it didn’t change, not to worry. A month later, he thought it was getting bigger and returned to the urologist who said they could go in and look to see if there is something of concern. The surgical report indicated that is was indeed a vericocele and a hydrocele (fluid buildup) and that the fluid was drained but they did not want to touch the vericocele for fear it would affect his ability to reproduce. Two months later, he came home on Christmas break and was complaining about pains in his upper back. Being an athlete, he thought it was just a sprained muscle and let it go. Back at school, the pain wasn’t getting any better and the doctor prescribed anti-inflammatory meds and sent him back to his studies. After a few weeks on these meds, and the pain was not getting any better, he went back to the doctor who then prescribed acid reflux medication. Eight months after the initial vericocele diagnosis, and five months after the complaints of upper back pain, he was diagnosed with Stage 4 Alveolar Rhabdomyosarcoma. It turns out that the primary site was the testicle and at this time the cancer had metastasized to his lymph nodes and bone marrow.

  • Constipation? After numerous days of not being able to go to the bathroom, the toddler was taken to the doctor’s office and examined by a Physician’s Assistant (PA) who recommended that she be given a laxative twice a day until she was going a significant amount on a regular basis. Even increasing the dosage of the laxative, nothing was moving. Three weeks after seeing the PA, she vomited from her nose and mouth and her parents noticed a bulge near her belly button. An ultrasound was done and the tech noted that she had a full bladder and that her intestines were full but they couldn’t see her appendix, which her physician thought might be the source of the bulge. The parents were told to purchase enemas and start giving them in addition to the high dose of laxative and, if nothing happened, to return in a week. Nothing was helping. While giving the youngster a tummy rub, her mother noticed a lump that was just above her left hip bone and also noted that her left leg was swelling. Three weeks after the initial visit with the PA, she was taken back to the doctor and another ultrasound was ordered but this time at the annex of the children’s hospital. The scan showed a large mass so a CT scan was ordered. The doctor said it was the largest mass he had ever seen in a child of her size and that it was almost certainly cancer. Now four weeks since the initial visit, the diagnosis was given to the parents – stage 4, group 4 Rhabdomyosarcoma.

Types of Rhabdomyosarcoma

Rhabdomyosarcoma can occur throughout childhood and may even be present at birth. It is a rare form of cancer but a further complication is that there are two major subtypes – embryonal and alveolar – which behave differently and require different treatments. The alveolar subtype is often referred to as “fusion positive or PAX-FOX0 fusion positive” rhabdo.

The embryonal subtype occurs most often in the head and neck area or in the genital or urinary organs. It is most often seen in children under the age of five while the alveolar subtype occurs most often in the arms or legs, chest, abdomen, genital organs, or anal area. While it occurs in all age groups, it usually occurs during the teen years.

In addition, there are several other sub-types of this disease:

  • Botryoid: A sub-type of embryonal Rhabdo, botryoid tumors arise under the mucosal surface of body orifices such as the vagina, bladder, nasopharynx and biliary tract. They represent approximately 10% of all rhabdo cases.
  • Spindle Cell: Another sub-type of embryonal rhabdo, spindle cell tumors typically found in young males and most commonly involves the paratesticular region followed by the head and neck.
  • Sclerosing: This is a newly recognized form of Rhabdo and can occur in both children and adults. Many of the qualities of Sclerosing Rhabdo overlap those of Spindle Cell and the two are often combined and classified as “spindle cell/sclerosing RMS.”
  • Anaplastic (Pleomorphic): Is an uncommon form of Rhabdo that occurs in adults but is very rare in children.

While certain risk factors have been identified, in general, the causes of RMS are not yet fully understood.

Signs and Symptoms of Rhabdomyosarcoma

Lumps and other symptoms may be caused by childhood rhabdomyosarcoma. The symptoms that occur depend on where the cancer forms. Other conditions may cause the same symptoms. Check with a doctor if your child has any of the following problems:

  • A lump or swelling that keeps getting bigger or does not go away. It may be painful, but sometimes it is not. Note that the lump could be anywhere on the body, between the fingers, on the calf muscle, on the head or neck, vaginal or testicle areas… anywhere on the body.
  • Bulging of the eye or a drooping eyelid.
  • Headaches.
  • Trouble urinating or having bowel movements.
  • Blood in the urine.
  • Bleeding in the nose, throat, vagina, or rectum.

The symptoms of rhabdomyosarcoma may resemble other conditions or medical problems which may cause a delay in the diagnosis and treatment. Always consult your child’s doctor for a diagnosis. Rhabdo can be an extremely fast growing cancer that can metastasize (spread) to other parts of the body. It is important that it be diagnosed quickly.

For additional information and an extensive list of resources, please check out the Resource Pages and read this post.

How is rhabdomyosarcoma diagnosed?

In addition to the physician knowing the complete medical history of the patient, a physical exam and a series of diagnostic procedures are used in the diagnosis process. These may include:

  • Biopsy of the tumor – if a tumor is found, a small sample of the mass is surgically removed or drawn through a needle and examined under a microscope. A biopsy is the only way to know for sure if the tumor is cancer and if it is, what type of cancer it is. The type of biopsy – needle or surgical – depends on the location of the mass, the age of the child and the expertise of the physician doing the biopsy.
  • Blood and urine tests
  • Multiple Imaging Studies
    • CAT Scan – Computerized tomography scan – an imaging procedure that uses a combination of X-rays and computer technology to produce images that represent slices of the body. A CAT scan can show detailed images of any part of the body, including the bones, muscles, fat, and organs. These scans produce far more detailed images that traditional X-ray images.
    • MRI – Magnetic Resonance Imaging – an imaging procedure that uses large magnets, radio-frequencies, and a computer to produce detailed images of the various structures within the body.
    • Ultrasound – Sonography – an imaging procedure that uses high-frequency sound waves and a computer to create images of blood vessels, tissues, and organs. Ultrasound technology can help the physician see, in real time, how the specific part of the body is functioning.
    • Bone Scans – images that are produced of the bone after a special dye, one that is absorbed by the bone tissue, has been injected into the system. These are used to detect tumors and bone abnormalities.
  • Bone Marrow Aspiration and/or Biopsy – a procedure where a small amount of bone marrow fluid (aspiration) and/or solid bone marrow tissue (core biopsy) is taken for analysis of the number, size, and maturity of the normal and abnormal blood cells. The marrow is generally taken from the hip area.
  • Lumbar Puncture – Spinal Tap – a special needle is inserted between the bones in the lower back into the spinal canal – the area around the spinal cord. The pressure in the canal and brain can then be measured. A small amount of the cerebral spinal fluid (CSF)can be removed and sent for testing to determine if there is an infection or other problems.


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