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CD1a immunopositivity in perivascular epithelioid cell neoplasms: true expression or technical artifact? A streptavidin-biotin and polymer-based detection system immunohistochemical study of perivascular epithelioid cell neoplasms and their morphologic mimics

Summary Perivascular epithelioid cell neoplasms comprise a family of rare neoplasms composed of morphologically distinctive perivascular epithelioid cells exhibiting a “myomelanocytic” immunophenotype. The distinction of perivascular epithelioid cell neoplasms from other tumors with melanocytic and...

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Published in:Human pathology 2011-03, Vol.42 (3), p.369-374
Main Authors: Ahrens, William A., MD, Folpe, Andrew L., MD
Format: Article
Language:English
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Summary:Summary Perivascular epithelioid cell neoplasms comprise a family of rare neoplasms composed of morphologically distinctive perivascular epithelioid cells exhibiting a “myomelanocytic” immunophenotype. The distinction of perivascular epithelioid cell neoplasms from other tumors with melanocytic and smooth muscle differentiation can be difficult. A recent study has suggested that perivascular epithelioid cell neoplasms routinely express CD1a, a Langerhans cell–associated transmembrane glycoprotein involved in antigen presentation and that expression of this marker may be helpful in the distinction of perivascular epithelioid cell neoplasms from various mimics. We evaluated a series of perivascular epithelioid cell neoplasms and potential mimics for CD1a expression. A total of 54 cases (27 perivascular epithelioid cell neoplasms, 11 leiomyosarcomas, 10 melanomas, 6 clear cell sarcomas) were evaluated in 2 laboratories (Mayo Clinic Rochester: 31 cases, Carolinas Medical Center: 23 cases). Selected positive cases were retested at Carolinas Medical Center (11 cases) and Mayo Clinic Rochester (10 cases). Mayo Clinic Rochester methods were as follows: MTB1 clone (1:20, Novocastra, Newcastle-upon-Tyne, UK), heat-induced epitope retrieval in EDTA (pH 8.0), and Dako Advance detection system (Dako Corp, Carpinteria, CA) with background-reducing diluent. Carolinas Medical Center methods were as follows: MTB1 clone (1:30; CellMarque, Rocklin, CA), heat-induced epitope retrieval in Medium Cell Conditioner #1 (pH 8.0-9.0), and streptavidin-biotin detection system with diaminobenzidine chromogen, with and without biotin blocking. Scores were as follows: 1+, 5% to 25%; 2+, 26% to 50%; and 3+, more than 51%. Langerhans cells served as a positive internal control in all tested cases. All Mayo Clinic Rochester cases were negative. Sixteen Carolinas Medical Center perivascular epithelioid cell neoplasms (14 renal angiomyolipomas, 1 soft tissue perivascular epithelioid cell neoplasm, 1 pulmonary clear cell “sugar” tumor) showed CD1a immunopositivity (1+: 7 cases; 2+: 7 cases; 3+: 2 cases) when tested without biotin blocking, 11 of these cases were retested with biotin blocking and were negative. All non–perivascular epithelioid cell neoplasms were negative. All positive perivascular epithelioid cell neoplasms showed cytoplasmic staining only, without membranous staining. Ten Carolinas Medical Center positive perivascular epithelioid cell neoplasms were negative when retested a
ISSN:0046-8177
1532-8392
DOI:10.1016/j.humpath.2010.09.001