Myoepithelioma of the parotid gland initially diagnosed by fine needle aspiration cytology and immunocytochemistry: a case report.

Abstract

BACKGROUND:

Myoepithelioma is a rare, benign tumor of the salivary gland, most commonly affecting the parotid gland. Although the cytologic features of myoepithelioma are documented in a few case reports, it has rarely been diagnosed preoperatively by fine needle aspiration (FNA) cytology.

CASE:

A 33-year-old man presented with a left parotid swelling 2.5 cm in diameter and of about 5 years' duration. FNA smears showed bundles of spindle-shaped cells as well as plasmacytoid and stellate cells in sheets and dissociated forms. A few cells had nuclear grooves, and occasional cells showed intranuclear cytoplasmic inclusions. In May-Grünwald-Giemsa-stained smears, most of the cells had reddish cytoplasm. Red to purple, myxoid matrix was present as a scanty fibrillar substance and as globules surrounded by tumor cells vaguely reminiscent of adenoid cystic carcinoma. A cytodiagnosis of myoepithelioma was given and corroborated by immunocytochemical staining, which revealed a positive reaction for vimentin, smooth muscle actin and S-100 protein. Epithelial membrane antigen yielded a negative reaction except for a few plasmacytoid cells with weakly positive staining. Histopathology of the resected tumor and immunohistochemical staining confirmed the cytodiagnosis of myoepithelioma.

CONCLUSION:

FNA cytologic features together with immunocytochemical studies on smears can offer a preoperative diagnosis of myoepithelioma.

• Authors: Dilip K Das, Bahiyah E Haji, Mahmoud S Ahmed, Mohamad N Riyad Hossain
• Journal: Acta cytologica (Acta Cytol) 2005 Jan-Feb Vol. 49 Issue 1 Pg. 65-70 ISSN: 0001-5547 [Print] Switzerland
• PMID: 15717758 (Publication Type: Case Reports, Journal Article)

Chemical References

• S100 Proteins

Topics

• Adult
• Biopsy, Fine-Needle
• Cytodiagnosis
• Humans
• Immunohistochemistry
• Male
• Myoepithelioma (diagnosis, pathology)
• Parotid Neoplasms (diagnosis, pathology)
• S100 Proteins (chemistry)
• Staining and Labeling