- What is the diagnosis?
There is a diaphyseal mass lesion. The plain film radiograph (image 2.1) shows the lytic lesion in the center of a mass lesion that extends from the bone cortex into adjacent soft tissue. The MRI scan (image 2.2) through the mid-calf shows irregular bright extension of the tumor into the soft tissue adjacent to the fibula. The normal bone cortex is dark while marrow (containing fat) is bright. The gross appearance of the resected lesion (image 2.3) shows that this irregular mass extends within the marrow cavity and through the cortex. There are hemorrhagic and lytic areas. There is prominent periosteal new bone formation in response to cortical erosion by the mass that is breaking through and expanding the cortex and extending into the adjacent soft tissue. The microscopic images 2.4 - 2.6 show that this is one of the so-called "small round blue cell tumors" and is Ewing sarcoma. The infiltrative and destructive nature of this tumor indicated that it is aggressive and malignant. The cells are small and primitive and round, and it is not clear what the cell of origin is, but these cells characteristically make lots of glycogen, as seen in image 2.7.
These lesions are a form of primitive neuroectodermal tumor (PNET). Most have a t(11;22) translocation with formation of the EWS:FL11 fusion gene that codes for a protein acting as a strong transcription factor to drive cellular proliferation.
- In whom and at what sites is this lesion most common?
There is slight male predominance. Ewing sarcoma is seen mostly in children to young adults, with the pelvis and lower extremities accounting for most of the sites of origin. The diaphysis is usually involved.
- What are some other small round cell tumors of childhood?
Langerhans cell histiocytoses (cousins of lymphoma), such as histiocytosis X and eosinophilic granuloma, may occur in bone in children.
Other round cell malignancies of childhood (not commonly involving bone)
include medulloblastomas of brain, neuroblastomas of adrenal, and retinoblastomas of eye.
- Who decides what kind therapy he gets?
This brings up the issue of treatment of minors, and consent for treatment. In this case, treatment may consist of surgery (with a decision for limb-sparing surgery or amputation), chemotherapy, and radiotherapy. The patient is a teenager (or, an adolescent). At what age can a person make important medical decisions? This is the wrong way to start thinking about this topic, for two reasons. First, there is no one age at which everybody is able to make such decisions; people differ in maturity and in cognitive sophistication. Second, diseases vary in severity and in the importance of the treatment decisions.
It is better to ask at what point minors should be included in the discussion and decision making, rather than excluded. The answer is: as early as possible, and certainly by age 7. Then, as they participate more and understand more, they can become a bigger part of the final decision making process. This encourages their growth, rather than waiting for some magic moment when they are suddenly called adults.
If you start treating children with respect and encouraging their participation at age 7, then certainly by the time they are teenagers they can make all important decisions mutually with their parents. That gives them five full years to prepare for their 18th birthday, when the law in all 50 states in the U.S. says they are officially adults.
Ewing sarcoma typically occurs in the first two decades of life. The patients should always be part of the decision making. And ethically, doesn't that make sense? After all, it is their limb you are talking about amputating! This is part of the 'mature minor' process. The American Academy of Pediatrics recommends that most minors are capable of participating in such a major medical decision by age 14.
