Benign Myoepithelial Neoplasms of Salivary Glands, Clinicopathologic Features and Review of the Literature

Introduction

Myoepitheliomas (ME) are rare, benign neoplasms composed of myoepithelial cells with a highly variable histologic presentation profile; recognized subtypes include spindle, plasmacytoid/hyaline, epithelioid, and clear. This article presents the largest single-center case series with regards to this neoplasm class. Cases were analyzed with emphasis placed on relevant histological presentation, clinical appearance, and demographics. A 15-year literature review is included as a point of comparison.

Materials and Methods

Institutional case series with accompanying 15-year, retrospective literature review.

Results

Institutional Case Series:</em> </strong>The retrospective search revealed 13 cases of myoepithelial salivary gland tumors—9 benign myoepitheliomas & 4 malignant myoepithelial tumors (included for comparison). Tumor morphology was analyzed—epithelioid pattern, 6 cases (4 benign, 2 malignant); spindle cell pattern, 6 cases (4 benign, 2 malignant); plasmacytoid pattern, 7 cases (6 benign, 1 malignant). The characteristics of connective tissue stroma were also analyzed. The stroma was myxoid in 2 cases (1 benign, 1 malignant), fibrous in 5 cases (4 benign, 1 malignant), and necrotic in 2 cases (2 malignant). The difference in reported clinicopathologic characteristics was not statistically significant, except for the presence of mitosis (p=0.001).

Literature Review

The search revealed 139 records. 32 articles including 34 cases were included. Cell morphology and stromal features were analyzed. The pattern of tumor cells included—epithelioid, 9 cases (29%); spindle cell, 13 cases (41%); plasmacytoid, 14 cases (45%). The stroma was myxoid in 11 cases (40%), fibrinous in 9 cases (33.3%), and necrotic in 2 (7.4%) cases.

Conclusions

Rare salivary gland tumors, especially those arising in atypical locations with ambiguous morphological patterns, present a unique diagnostic challenge. Due to myoepithelioma's ability to manifest in the various glandular structures of the head and neck, dental professionals and physicians who encounter head and neck pathology must recognize this entity as part of their differential diagnosis when clinically appropriate