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40 year old man presenting with mild proptosis and downward displacement of the globe.
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Specimen labelled "orbital roof tumor": Hemangioma involving bone, dura, orbit and periorbita
On discussing the composition of part D "superior orbita" with
[...], he noted that this tissue actually comes from the periorbita as well as the orbit. In as much it is difficult to interpret the vessels in the adipose tissue as being part of the lesion or residential blood vessels and the fragment of tumor present in this part is not in adipose tissue, it is possible that this tumor is from the periorbita.
The tumor is a vascular lesion. The morphology is consistent with hemangioma. Both Dr. [...] and Dr.[...], sarcoma pathologists, have examined this case and agree this lesion is hemangioma.
Sections show a tumor comprised of cells with round to elongated nuclei demonstrating a mild degree of pleomorphism. These cells have eosinophilic cytoplasm with ill-defined cell borders. The tumor is vascular and has numerous small, thin-walled channels, as well as larger thin-walled channels. The thin-walled vessels, which are essentially comprised only of endothelium. Thrombosis is seen in some of the vascular channels, and eosinophilic fibrinoid material is seen in some of the intervening tumor parenchyma. Mitotic figures are not evident. There are no areas of necrosis. Focal bone formation is seen, particularly adjacent to the dura, although focal areas of bone are also seen within the tumor parenchyma. Some of the latter are associated with adjacent hyaline matrix. The tumor is reticulin-positive, the reticulin outlining the blood vessels as well as individual and groups of cells between blood vessels. PAS positivity is seen between tumor cells. Alcian blue positivity is seen in the areas adjacent to the bone as well as in the walls of some of the blood vessels.
Immunocytochemistry shows the tumor is positive for vimentin. It is negative for epithelial membrane antigen and keratin. Immunocytochemistry for CD31 and CD34 show positivity in the endothelium. Some cells between vessels show positivity for CD34, but it is difficult to discern whether these are truly cells or collapsed thin-walled blood vessels. The tumor is positive for O13. No areas of S100 positivity are seen in the tumor. Generally scattered nuclei are positive for the cell proliferation marker MIB-1; however, there are several clusters of cells where most cells are positive.
Electron microscopy shows the tumor is comprised of numerous blood vessels. The vessels are so numerous that it is difficult to be certain which cells are those of blood vessels and which are intervening cells. In the extracellular space, there is collagen, some of which appears to be wide-spaced collagen, and amorphous material which is consistent with basement membrane material.
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