|
| Figure 6. Immunostain for cytokeratin intermediate filaments with antibody AE1/AE3. |
Diagnosis and Discussion:
The case was diagnosed as osteogenic sarcoma with aberrant
expression of cytokeratin intermediate filaments and structural
differentiation of desmosomes and tonofilaments. For the primary
vertebral tumor and in the majority of the recurrences and metastasis,
frozen tissue was available for immunohistocehmistry. The results
in Table 1 summarize the significant immunostains and Figure 6
is an example of the moderate to strong cytoplasmic staining staining
of a proportion of the tumor cells with AE1/AE3.
|
|
|
| Antibody | Result |
| Cytokeratin - AE1/AE3 | Positive in all 4 samples |
| Cytokeratin - CAM 5.2 | Positive in only primary and 1989 recurrence |
| Vimentin | Positive in all 4 samples |
| GFAP | Only primary tumor positive (5-10 percent of cells) |
| EMA | All 4 samples positive (5-10 percent of cells) |
|
|
| Figure 6. Immunostain for cytokeratin intermediate filaments with antibody AE1/AE3. |
A battery of different sarcomas have been shown to occasionally express cytokeratin intermediate filaments. This can be thought of as a functional aberration of gene regulation in a tumor. The plasticity of this process in some sarcomas is evident in the current tumor where antibody CAM 5.2 detected certain low molecular weight cytokeratins in only two samples and GFAP intermediate filaments were expressed only in the primary tumor. What is unique, however, about this case of osteogenic sarcoma is the aberrant expression of genes regulating structural cellular elements such as tonofilaments and a complex organelle, the desmosome. Since these elements were present in all five samples from this case, such abnormal gene expression was a fixed component of this neoplasm.
Reference:
Dardick I, Schatz J, Colgan T: Cytokeratin expression in an osteogenic
sarcoma. Ultrastruct Pathol 16:463-474,1992.
