Case Diagnosis and Discussion

Diagnosis

Epithelioid Angiosarcoma of the duodenum and stomach.

Discussion

Angiosarcoma involving the gastrointestinal tract is very rare, is often multicentric, and may involve the gastrointestinal tract as a primary tumor, a metastatic tumor, or by direct extension from a retroperitoneal tumor [1]. Gastrointestinal tract angiosarcoma usually presents with gastrointestinal bleeding, anemia, and/or melena and due to this non-specific presentation, there may be a delay in the initial diagnosis [1]. These tumors more commonly involve the colon and small intestine and are rare in the stomach [1].  Gastrointestinal tract angiosarcomas have a dismal prognosis and most patients die within 6 months, usually of uncontrollable hemorrhage [1].

The epithelioid variant of angiosarcoma, originally described in cutaneous tumors by Rosai et al. [2], has a propensity to masquerade as other tumors, particularly primary or metastatic poorly differentiated carcinoma, as well as melanoma, lymphoma, or mesothelioma [1]. Confounding this diagnostic pitfall, the epithelioid variant of angiosarcoma is well-known to aberrantly express cytokeratins [1, 3]. CD31 is a reliable immunohistochemical stain to resolve this differential diagnosis and is consistently positive in epithelioid angiosarcoma [1].

Endoscopically, gastrointestinal tract angiosarcomas are described as red or red-brown, polypoid mucosal-based lesions [1]. Histologically, epithelioid angiosarcomas of the gastrointestinal tract are composed of diffuse sheets of epithelioid cells with subtle clefting suggestive of vascular differentiation that fill the lamina propria [1]. The glands are typically preserved and there may be overlying erosions [1]. Cytologically, the cells are epithelioid with amphophilic to eosinophilic cytoplasm and hyperchromatic nuclei with prominent nucleoli [1]. There may be occasional intracytoplasmic lumina containing red blood cells [1].

Although angiosarcoma is a very rare tumor of the gastrointestinal tract, it is important to be aware of this entity and its ability to impersonate a poorly differentiated carcinoma, both morphologically and immunophenotypically; this is especially true when dealing with small endoscopic biopsy material.

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References:

1. Allison KH, Yoder BJ, Bronner MP, Goldblum JR, Rubin BP. Angiosarcoma involving the gastrointestinal tract: a series of primary and metastatic cases. Am J Surg Pathol. 2004;28(3): 298-307.
2. Rosai J, Sumner HW, Kostianovsky M, Perez-Mesa C. Angiosarcoma of the skin. A clinicopathologic and fine structural study. Hum Pathol. 1976;7(1):83-109.
3. Fletcher CDM, Beham A, Bekir S, Clarke AMT, Marley NJE. Epithelioid angiosarcoma of deep soft tissue: a distinctive tumor readily mistaken for an epithelial neoplasm. Am J Surg Pathol. 1991;15(10):915-924.

This case was presented in abstract format at the College of American Pathologists 2013 annual meeting in San Diego, CA.