Acinic Cell Carcinoma Case Study

Acinic cell carcinoma is believed to arise from progenitor reserve cells of the intercalated ducts of salivary tissue. Although characteristically slow growing with clinical behavior reflective of a low-grade tumor, acinic cell carcinoma can recur in 25—50% of patients if not treated adequately [Spafford et al, 1991]. A subset of acinic cell carcinomas are clinically more aggressive with metastasis to regional lymph nodes and distant sites, particularly the lung, at presentation. Histologic grading of acinic cell carcinomas is controversial and, unlike clinical stage, histomorphology has not proven to be reliable in predicting behavior. The diagnosis of acinic cell carcinoma in both cytologic and resection specimens requires documentation of focal serous acinar differentiation, the hallmark of this tumor. When the tumor is composed of predominantly solid acinar-type cells, the diagnosis is straightforward. The wide range of cell types and architectural patterns that can be seen in some cases yields a broader differential diagnosis, which includes mucoepidermoid carcinoma, oncocytoma, cystadenoma, and cystadenocarcinoma. The identification of serous-type acinar differentiation and the absence of epidermoid and mucinous cells distinguishes acinic cell carcinoma from these other neoplasms. For diagnostically difficult cases, periodic acid Schiff (PAS) plus diastase, a special staining technology, can be used as an ancillary histochemical marker to highlight the cytoplasmic zymogen granules characteristic of acinar cells.
Diagnostic x-ray films are limited in their usefulness and sialograms provided only visualization of accessory glands for diagnostic purposes.[Formmer, 1977] Magnetic resonance imaging and CT sialography are useful for visualizing the accessory parotid gland tumors separately from the main parotid gland.[Hamano et al,