8 year old child complaints of swelling in middle of thigh, with codmans triangle on xray on biopsy round cells with glycogen positivity are seen. Diagnosis is
a. Ewing sarcoma is the most common primary malignancy of bone in patients younger than 10 years of age
b. Pain is an almost universal complaint of patients with Ewing sarcoma.
c. In addition to pain, patients also may have fever, erythema, and swelling suggesting osteomyelitis.
d. Laboratory studies may reveal an increased white blood cell count, an elevated erythrocyte sedimentation rate, and an elevated C-reactive protein.
e. To complicate matters further, a needle aspirate of Ewing sarcoma may grossly resemble pus, and the tissue may be sent in its entirety to microbiology and none to pathology. (As a general rule, all biopsy specimens should be sent for culture and pathological analysis.)
f. Classically, Ewing sarcoma appears radiographically as a destructive lesion in the diaphysis of a long bone with an “onion skin” periosteal reaction. In reality,
g. Ewings can also have codmans triangle and sun burst appearance which are more common in osteosarcoma.
h. Ewing’s sarcoma is a small round cell tumor, that typically has a clear cytoplasm on Hande staining, due to glycogen. The presence of the glycogen can be demonstrated with positive PAS staining .The characteristic immunostain is CD99 which diffusely marks the cell membrane.