Bilateral syringomatous adenomas of the nipple: Case report with immunohistochemical characterization of a rare tumor mimicking malignancy.

OBJECTIVES

Syringomatous adenoma of the nipple (SAN) is a rare benign infiltrative neoplasm that may be confused with low-grade breast carcinomas. We report the case of 71-year-old woman with a fungating left breast mass and subareolar calcifications in the contralateral breast.

METHODS

Histomorphologic features were evaluated with standard H&E-stained sections. Both lesions were also evaluated by immunohistochemistry for further characterization. A literature review was performed to place the current case in context relative to previous observations.

RESULTS

Both lesions were infiltrating syringomatous adenomas, confirmed by detailed immunohistochemical analyses, which also provided new evidence for the putative sweat duct origin for these tumors. The debated presence of myoepithelial cells in these lesions was newly and convincingly supported in this study by strong diffuse immunostaining of the outer cell layer of the tubules for smooth muscle myosin, cytokeratin 34βE12, cytokeratin 5/6, and p63. Previous reports describing similar detailed immunophenotypical characterization of these uncommon tumors are lacking.

CONCLUSIONS

To our knowledge, this case represents only the second reported patient with bilateral SAN and the first such case to be reported in the pathology literature.