Rhabdomyosarcoma Health Article

Definition

Rhabdomyosarcoma is a childhood cancer. It begins in cells that will become skeletal muscle cells. Skeletal muscle is attached to bones and is different from the smooth muscle that lines the intestinal tract (esophagus, stomach, small and large intestines). With rhabdomyosarcoma, these muscle cells grow uncontrollably and form masses or lumps called tumors. They can start almost anywhere in the body where there is skeletal muscle.

Description

Rhabdomyosarcomas can start in any organ that contains skeletal muscle cells, but most commonly tumors are found in the head and neck and in the prostate, bladder, and vagina. From 5-8% of all cancers diagnosed in children are rhabdomyosarcomas.

Demographics

Rhabdomyosarcoma occurs most frequently in children ages 2 to 6 and 15 to 19 years old. More males than females develop rhabdomyosarcomas. Among younger children, the tumor is usually in the head and neck and may involve the area surrounding the eye. Less often, young children develop rhabdomyosarcomas of the genitourinary tract (bladder, prostate, vagina).

In the older age group, the most likely site is the male genitourinary tract, especially the testes and surrounding area. Other body parts where rhabdomyosarcoma may begin are on the arms, legs, trunk, or deep inside the abdomen (retroperitoneum).

Some cases of rhabdomyosarcoma run in families and are linked to genetic syndromes. Immediate family members of children with rhabdomyosarcoma are at increased risk of developing certain cancers that are not rhabdomyosarcomas, such as breast and brain tumors.

Causes and symptoms

The causes of rhabdomyosarcoma are not known. Certain inherited conditions that run in families increase the risk of developing this cancer. Rhabdomyosarcoma has been linked to medical conditions such as fetal alcohol syndrome, neurofibromatosis, Gorlin's syndrome, and Li-Fraumeni syndrome.

The symptoms of rhabdomyosarcoma depend on the site of the tumor and whether it has spread. When rhabdomyosarcoma begins in the head, it may involve the area surrounding the eye, the nasal passages or the ear and throat. Tumors in these areas may cause swelling, especially around the eye; blocked nasal passages or sinuses; ear pain and bleeding; and difficulties swallowing. Rhabdomyosarcomas in the head and neck may also put pressure on the brain or nerves.

When rhabdomyosarcoma affects an arm, leg or other body part, the swelling may be mistaken for a bruise or other injury. When the genitals or urinary tract are involved, there may be symptoms such as recurring urinary tract infections, blood in the urine, incontinence, or blockage of the urinary tract or rectum.

Rhabdomyosarcoma affecting the testes may cause swelling of the scrotum. When the uterus or vagina is affected, there may be a mass or small tumor pushing into the vaginal canal.

Diagnosis

Some patients who have rhabdomyosarcomas go to the doctor because they have discovered a lump or mass or swelling on a body part. Others have symptoms related to the part of the body that is affected by the tumor. The patient's doctor will take a detailed medical history to find out about the symptoms. The history is followed by a complete physical examination with special attention to the suspicious symptom or body part.

Depending on the location of the tumor (mass or lump), the doctor will order imaging studies such as x ray, ultrasound, computed tomography (CT) scans and magnetic resonance imaging (MRI) to help determine the size, shape and exact location of the tumor. The doctor may also order bone scans to determine if the tumor has spread to bones. Blood tests will be done and an examination of the bone marrow also may be performed.

A biopsy of the tumor is necessary to make the diagnosis of rhabdomyosarcoma. During a biopsy, some tissue from the tumor is removed. The tissue sample is examined by a pathologist, a doctor who specializes in the study of diseased tissue.

Types of biopsy

The type of biopsy done depends on the location of the tumor. For some small tumors, such as those on the arm or leg, the doctor may perform an excisional biopsy, removing the entire tumor and a margin of surrounding normal tissue. Most often, the doctor will perform an incisional biopsy, a procedure that involves cutting out only a piece of the tumor. This biopsy provides a core of tissue from the tumor that is used to determine its type and grade.