How are vascular sarcomas of the pleura differentiation from metastatic pleural disease?

Updated: Dec 25, 2019
  • Author: Joseph F Tomashefski, Jr, MD; more...
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Answer

One must always consider the possibility of metastatic pleural disease before concluding that a vascular sarcoma is primary in the pleura. Both EHE and epithelioid angiosarcoma can be mistaken for metastatic carcinoma involving the pleura. [97] In general, carcinomas exhibit necrosis, prominent desmoplastic stroma, greater cellular pleomorphism, and evidence of epithelial differentiation compared to EHE.

Intracytoplasmic lumina of EHE may resemble the appearance of signet ring cells; however, mucicarmine stain is negative. Strong immunostaining for cytokeratin and the absence of endothelial markers in carcinoma help differentiate these 2 entities. Pseudoangiomatous squamous carcinoma is notable for simulating angiosarcoma owing to a lack of keratin formation and acantholysis of squamous nests which simulate anastomotic vascular channels. [55] CD10 positivity in EHE may simulate metastatic renal cell carcinoma or other tumors which express CD10. [79]

Metastatic melanoma involving the pleura can be excluded based on its distinctive immunohistochemical profile.

Finally, epithelioid sarcoma, a low-grade sarcoma usually arising in the extremities of young adults, may metastasize to the pleura and resemble EHE. Compared to EHE, epithelioid sarcoma tends to be histologically more pleomorphic and may have focal necrosis. In contrast to EHE, epithelioid sarcoma lacks significant myxohyaline stroma, and the cells have more eosinophilic nonvacuolated cytoplasm. Epithelioid sarcomas consistently express cytokeratin and EMA in addition to vimentin and may also be positive for CD34. Epithelioid sarcoma, however, lacks the more specific endothelial markers CD31 and factor VIII–related antigen.


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