Aspirates of pleomorphic adenoma (benign mixed tumor; BMT) contain a combination of chondromyxoid stroma, sheets and clusters of epithelial cells, and mesenchymal cells.
Acinic cell carcinoma is a slowly growing, low grade malignant salivary gland tumor most often arising in the parotid. It is the most common malignant salivary gland tumor in children. Aspirates are usually very cellular, yielding many sheets and clusters of tumor cells that are larger than normal acinic cells, varying markedly in size and shape. Nuclei are small and eccentric and the cytoplasm may be pale or granular. Many round, naked nuclei also commonly are present.
Mucoepidermoid carcinoma is the most common malignant salivary gland tumor in adults. Low grade tumors consist of sparsely cellular, thick, mucoid material containing a combination of intermediate cells with small nuclei and larger mucus-producing cells with clear cytoplasm. High grade tumors usually yield specimens that are more cellular, containing malignant squamous cells, with a scant mucinous component. Squamous cells usually are not keratinized. Intermediate grade tumors may contain squamous cells that appear deceptively benign, in addition to occasional mucus-producing and intermediate cells.
Metastatic thyroid follicular carcinoma may display rosettelike microfollicles and would not have the acellular, spherical globules of metachromatic hyaline material shown in the photomicrograph.
This malignant tumor typically presents as a slowly enlarging, painful mass due to frequent involvement of the facial nerve.
