Vascular lesions: Avoiding diagnostic pitfalls

Seattle - Accurate diagnosis of vascular proliferations can be both difficult and critical, given a relatively wide disparity in clinical outcome between the different types of lesions, according to Omar P. Sangueza, M.D., professor and director of dermatopathology at the Wake Forest University School of Medicine, Winston-Salem, N.C.

In a presentation at the 42^nd Annual Meeting of the American Society of Dermatopathology in Seattle, Dr. Sangueza presented clinical cases that highlighted this point, explaining the diagnosis of relatively innocent lesions that can be mistaken for Kaposi's sarcoma or angiosarcoma.

"My purpose here is to teach people how to recognize a variety of lesions and give them their proper name so that appropriate treatment is provided," Dr. Sangueza tells Dermatology Times. "Avoiding overdiagnosis is crucial because the clinical outcome of Kaposi's sarcoma and angiosarcoma are typically very poor."

Historically, Kaposi's sarcoma was a rare form of relatively benign cancer that tended to occur in elderly men of Mediterranean or African heritage and immunocompromised patients. But in the early 1980's, several cases of a more aggressive form of Kaposi's sarcoma was identified in the United States among homosexual men with advanced HIV infection. Today, in the United States, Kaposi's sarcoma is known as a clinically aggressive, AIDS-defining illness in which morbidity can occur from extensive cutaneous, mucosal or visceral involvement.

Kaposi's sarcoma can be easily confused with a number of other soft tissue lesions, including, Dr. Sangueza says, several benign vascular proliferations. Two important examples would include benign lymphangioendothelioma and spindle cell hemangioma, both of which occur in young adults.

Benign lymphangioendothelioma clinically presents as large infiltrative plaques usually on the lower extremities. Histologically, the lesions are very similar to those of Kaposi's sarcoma, except for the absence of plasma cells.

Spindle cell hemangioma is histopathologically comprised of well-circumscribed, non-encapsulated nodules having features of both hemangioma and Kaposi's sarcoma. Nodular forms of Kaposi's sarcoma constitute a singular differential diagnosis with spindle cell hemangioma. The nodules of Kaposi's sarcoma distinguishingly have very few dilated blood vessels, generally without epithelioid round cells with vacuolated cytoplasm. Additionally, the presence of the human herpes virus 8 in Kaposi's sarcoma individualizes the lesion.

Angiosarcomas

Angiosarcomas are rare vascular neoplasms that tend to be clinically aggressive and difficult to treat, with a low survival rate. Patients who present at advanced stages and do not undergo extensive excision are likely to have higher rates of recurrence and distant metastasis, as well as worsened survival. Although the etiology of most cases of angiosarcoma is unknown, lesions have been observed after mastectomy for breast carcinoma and in areas that have been irradiated.

According to Dr. Sangueza, poorly differentiated angiosarcomas demonstrate solid proliferations of polygonal or spindle-shaped pleomorphic endothelial cells, with prominent mitotic activity and poorly-formed vascular spaces. This can make them difficult to distinguish from carcinoma, melanoma, or a high-grade fibrosarcoma.

In these cases, the presence of cytoplasmic vacuoles within the neoplastic cells is valuable in the differential diagnosis of poorly differentiated angiosarcomas. In addition, few-to-no erythrocytes are present within the vascular spaces.

These and other histopathological considerations in differential diagnosis can reduce over-and under-diagnosis of aggressive disease and subsequent risk to the patient, Dr. Sangueza says.

"That's why it is so important to make a proper diagnosis of a vascular proliferation," he concludes. "This area of study has become very important today."

Disclosure: Dr. Sangueza reports no disclosures pertinent to this article.

For more information:
http:// http://www.wfubmc.edu/pathology/faculty/sangueza.htm
http:// http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?CMD=search&DB=pubmed/
http:// http://www.asdp.org/search_member.php?ID=35113/