Journal Article

40 A Case of Atypical Myoepithelial Predominant Benign Mixed Tumor With Prominent Myxoid Stroma of the Salivary Gland

Lubna Alattia and Nestor Dela Cruz

in American Journal of Clinical Pathology

Published on behalf of American Society for Clinical Pathology

Volume 149, issue suppl_1, pages S17-S18
Published in print January 2018 | ISSN: 0002-9173
Published online January 2018 | e-ISSN: 1943-7722 | DOI: https://dx.doi.org/10.1093/ajcp/aqx116.039
40 A Case of Atypical Myoepithelial Predominant Benign Mixed Tumor With Prominent Myxoid Stroma of the Salivary Gland

Show Summary Details

Preview

Abstract

Background

Pleomorphic adenoma is a benign tumor characterized microscopically by the presence of epithelial and modified myoepithelial cells intermingled mainly with the chondroid, and less frequently with the myxoid stroma. The myoepithelial cells are usually positive for vimentin, glial acidic fibrillary protein (GFAP), c-kit, p63, and S100 protein.

Methods

We present unusual morphologic and immunophenotypic characteristics for a benign mixed tumor, in a 9-year-old African American boy who presented with a painless, gradually growing left parotid mass.

Results

Grossly, the lesion is a 4.6 x 3.9 x 3.2 cm solid mass that is firm, red, and irregular; also, it is entirely covered by a thin glistening capsule. Microscopic examination revealed a myoepithelial predominant benign mixed tumor with prominent myxoid stroma. The tumor is circumscribed, composed of irregular nests and cords of spindly epithelioid and plasmacytoid cells, some of which appear to have intercellular junctions. The myxoid stroma has areas of fibrosis with occasional mitosis and pyknotic cells. Invasive growth and perineural and intravascular spread are not seen. Immunohistochemistry stains show S100 is positive in 80% of the tumor cells, and the vimentin is diffusely positive; p63 is patchy positive in 5% of tumor. GFAP, p40, and c-kit are negative. The Ki67 is showing up to 6% nuclear staining. Pankeratin is positive; CK7 shows patchy staining. More specifically, muscle specific actin is 1 to 2+ diffusely positive, and smooth muscle actin is diffusely 2+ positive on myoepithelial markers cells.

Conclusion

We present a myoepithelial predominant pleomorphic adenoma, characterized by irregular nests and spindly epithelioid cords as well as plasmacytoid cells that are negative for GFAP and c-kit. It is positive for the more specific myoepithelial markers, such as smooth muscle actin.

Journal Article.  0 words. 

Subjects: Medical Skills ; Pathology

Full text: subscription required

How to subscribe Recommend to my Librarian

Users without a subscription are not able to see the full content. Please, subscribe or login to access all content.