33 Special Types of Invasive Breast Carcinoma: Diagnostic Criteria ...

As noted above, any soft-tissue sarcoma or soft-tissue tumor can arise from breast
connective tissue, but a relatively rare malignant stromal tumor (sarcoma) showing
endothelial-cell differentiation deserves special consideration. This is known as
primary breast angiosarcoma, which can occur de novo within the breast parenchyma
or be secondary in patients following radiation therapy or long after radical
mastectomy complicated by chronic lymphedema (Stewart Treves Syndrome).
Conservative approaches to surgical therapy have largely eliminated Stewart Treves
Syndrome.
Angiosarcoma of the breast may be difficult to palpate and to find in mammograms,
but in some cases, a palpable mass may be discernible (142-146). Usually, breast
angiosarcomas produce soft, spongy, and hemorrhagic areas. Tumor cells form
irregular, invasive, anastomosing vascular channels that are lined by atypical
(hyperchromatic) endothelial cells, but the cytologic features may vary, ranging from
a highly undifferentiated solid tumor to one that is very bland cytologically and
difficult to distinguish from benign vessels (142-146). Malignant vessels of
angiosarcoma invade breast parenchyma diffusely and show no "respect" for normal
breast structures. Some authors have observed the prognosis of breast angiosarcoma to
correlate nicely with histologic grade, although traditionally breast angiosarcoma has
been considered to have a universally poor prognosis (144-146). In fact, Rosen and
coworkers report that the overall survival of patients with breast angiosarcoma is
roughly 33% at 5 years, but the majority of patients with well-differentiated tumors
will survive 5 years (144, 145). Tumor cells are positive for endothelial markers such
as factor VIII–related antigen (vVF), CD31, and CD34. Some high-grade epithelioid
tumors may mimic carcinoma, but the majority show immunoreactivity for the
aforementioned endothelial markers. The differential diagnosis of breast angiosarcoma
includes poorly differentiated breast carcinoma, metaplastic carcinoma, acantholytic
squamous carcinoma, various benign hemangiomas (hemangiomatoses),
hemangiopericytoma, cystic hygroma, cellular angiolipoma, and pseudoangiomatous
stromal hyperplasia (113, 142-156). Cellular angiolipoma may be particularly
troublesome, but it shows hyaline thrombi within cytologically bland capillaries and is
often well circumscribed. In this spectrum of vascular lesions, atypical vascular
lesions, lymphangioma-like nodules, and overt angiosarcomas of breast and/or
overlying skin have been reported following segmental resection with edema and after
radiation therapy (116, 117, 157-161). The latter phenomenon is somewhat
reminiscent of so-called lymphangiosarcoma of the upper extremities as a result of
long-standing postmastectomy lymphedema (Stewart-Treves syndrome) (142-146).
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