Pathology of Epithelioid Angiosarcoma
Sakamoto A, Takahashi Y, Oda Y, Iwamoto Y. Aggressive clinical course of epithelioid angiosarcoma in the femur: a case report. World Journal of Surgical Oncology. 2014;12:281. doi:10.1186/1477-7819-12-281.
The epithelioid variant of angiosarcoma was first described in cases of cutaneous angiosarcoma by Rosai et al in 1976 and later documented in deep soft tissue by Weiss et al. and Fletcher et al.
Epithelioid angiosarcoma is a rare rapidly growing malignant vascular tumour with an aggressive course.
Death occurs two to three years after presentation.
Site: Epithelioid angiosarcoma often arises in the deep soft tissues of the extremities, although a variety of other primary sites, including the thyroid gland, skin, and adrenal glands, have also been reported.
vanishingly rare tumour presents in middle aged and elderly male
The tumor is composed of pleomorphic, epithelioid cells with prominent nucleoli and atypical mitotic figures (a) and necrotic areas (b) . Neoplastic cells are strongly positive for CD31 (c)
Tumour consists of solid and infiltrative sheets of epithelioid cells characterised by large, oval to round cells with abundant eosinophilic cytoplasm, vesicular nucleus and eosinophilic nucleolus.
Intracytoplasmic vacuoles containing red blood cells are present in some cells.
In most cases there are vascular channels or cystically dilated spaces.
Reticulin stain highlights tubular vasoformative architecture.
In the absence of obvious vascular differentiation, abundant intratumoral hemorrhage and intratumoral neutrophils are useful ancillary morphologic features that may suggest a vascular origin.
A distinctive starry-sky histologic pattern has also been reported in some cases of epithelioid angiosarcomas.
Immunohistochemistry: The neoplastic cells showed positivity for endothelial cell markers - CD31, CD34, factor VIII-related antigen, and Ulex europaeus agglutinin I ; Epithelial markers - cytokeratins and sometimes epithelial membrane antigen; and vimentin.Differential diagnosis:
Differential diagnosis includes epithelioid hemangioma, epithelioid haemangioendothelioma , metastatic carcinoma, metastatic melanoma, lymphoma, epithelioid sarcoma , and many sarcomas with epithelioid features.
Epithelioid hemangioma usually affects younger patients, forming well-circumscribed lesions in which the soft-tissue component is usually less marked.
Well-formed vessels are characteristic and severe nuclear atypia is absent, signifying the benign nature of the condition.
Metastatic carcinoma can be difficult to distinguish from epithelioid angiosarcoma.
Both tumors are composed of epithelioid tumor cells, and they tend to affect older individuals.
Identifying histologic features of epithelioid angiosarcomas, including the presence of well-formed vascular channels and cytoplasmic vacuoles that contain red blood cell fragments, is essential.
Negative staining for S-100 and HMB-45 helps to exclude melanoma.
Epithelioid hemangioendothelioma is also a differential diagnosis of epithelioid angiosarcoma, because both tumors share a number of histopathologic features of epithelioid cells with intracytoplasmic lumina.
However, epithelioid hemangioendothelioma is a low-grade malignant vascular tumor with minimal cellular pleomorphism.
Epithelioid hemangioendothelioma is less aggressive than epithelioid angiosarcoma.
Epithelioid sarcoma, particularly the proximal-type variant (PES), may be morphologically similar to Epithelioid Angiosarcoma being composed predominantly of large epithelioid cells with prominent nucleoli and with variable cytological atypia . PES is typically positive for vimentin, cytokeratin, and epithelial membrane antigen (EMA), PES also frequently stains positively for CD34 but is negative for other markers of endothelial cell origin including CD31, Fli-1 and Factor VIII-related antigen.
Other possibilities to consider in the differential diagnosis include anaplastic large-cell lymphoma, epithelioid rhabdomyosarcoma, and epithelioid variants of malignant nerve sheath tumors.
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