Principles of Diagnosis and Treatment of Soft-Tissue Tumors in Children

Small tumors of the arms and legs in children are fairly common. Fortunately, they are also usually benign. A careful and accurate diagnosis is still important. And, of course, treatment of the tumors (whether benign or malignant) is challenging. That’s why Dr. M. M. Thacker from Alfred I. duPont Hospital for Children has written this in-depth, up-to-date article on pediatric soft-tissue tumors of the extremities.

Advances in our understanding of tumors in children have come from the use of imaging such as PET scans and whole body MRIs. Pathologic study of the tumor cells using immunohistochemistry, flow cytometry, and cytogenetic studies is helping researchers understand how tumors develop. This knowledge may eventually make it possible to specifically target and kill tumors without damaging the surrounding tissue.

Treatment principles of soft tissue masses in children depend on several factors. These include the type of tumor (benign versus malignant, slow versus fast growing), symptoms, and age of the child. For example, small, benign tumors that are not causing any symptoms or problems may be watched and monitored without doing anything. Most benign but symptomatic tumors are removed surgically. In some cases, fast growing tumors (even if benign) may be managed with chemotherapy and/or radiation.

Dr. Thacker provides detailed information about the most common benign and malignant soft-tissue tumors. Rhabdomyosarcoma (RMS) is the most common malignant soft tissue tumor in the 0 to 14 age group. This is one of the tumors that can be treated with chemotherapy without surgery (or minimal surgery) to avoid deformity and mutilation of the involved extremity (arm or leg). Children in the one to nine age categories have the best prognosis with this disease. There is a poor prognosis for children who have metastases to three or more areas of the body.

Other sarcomas (malignant tumors) that are not rhabdomyosarcoma (RMS) are referred to as non-RMS soft-tissue sarcomas include synovial sarcoma, liposarcoma, and other non-RMS sarcomas. Location, histology (tumor cell characteristics), treatment, and prognosis for each of these tumor types are discussed. CT scan images, cell histology, and photos of the tumors taken during surgery to remove them are provided.

As with most other malignant soft-tissue tumors, the potential for metastasis requires treatment. Treatment may consist of a combination of chemotherapy, radiation, and/or surgery. Targeted therapy is not available yet but may become an option in the future. For patients who experience local recurrence after treatment, radiation is the treatment of choice.

A separate section on common benign tumors covers similar information on lipomas, lipoblastomas, three types of fibromatosis (infantile myofibroma/myofibromatosis, lipofibromatosis, and desmoid fibromatosis), neurogenic tumors, granular cell tumor, and tenosynovial giant cell tumors (TGCT).

Benign means nonmetastasizing (does not spread to other parts of the body) but local growth can put pressure on other tissues creating other problems. And tumors can become large enough to present cosmetic problems and even deformity. Once again, every effort is made to provide treatment that does not cause mutilation of the extremity. More and more pharmaceuticals (chemotherapy-type drugs) are used in combination with surgical excision (removal) when necessary.

In summary, Dr. Thacker provides a very excellent review of benign and malignant soft-tissue tumors of the extremities in children (birth to age 19). He suggests that the physician making the diagnosis in these cases must be very thorough as many cases are extremely challenging. Diagnostic information must be gathered from multiple sources including the clinical presentation, imaging, and tissue biopsy and cell histology. This level of detailed diagnostic information also guides non-surgical management as well as treatment with all other modalities (radiation, chemotherapy, surgery).