Objective: To summarize the diagnosis and treatment outcomes of basal cell adenocarcinoma (BCAC) of the parotid gland, a rare low-grade malignancy, at a single institution, and to investigate the treatment approach for this rare malignancy.
Methods: We conducted a retrospective analysis of 9 patients with BCAC during 20 years from September 1999 to December 2019. Forty-five patients with basal cell adenoma (BCA), who were treated during the same time period, were used for comparison. The clinical characteristics of BCAC, diagnostic imaging, the usefulness of fine-needle aspiration cytology (FNAC) and frozen section biopsy (FSB), histological assessment of malignancy, and treatment outcomes were investigated.
Results: There were no marked differences in sex, age, tumor diameter, or tumor location between BCAC and BCA cases. Among the 9 patients with BCAC, one patient was noted with pain/tenderness, and two patients were observed with adhesion to the surrounding tissues. Only one patient was diagnosed as malignant based on MRI/US. FNAC for BCAC was suspicious for malignancy in 6 of the 9 cases, which included one patient with the correct grade of malignancy, one patient with malignancy only, and 4 patients suspicious for malignancy. FSB was suspicious for malignancy in 8 of the 9 cases. Malignancy grade was determined based on infiltration to the surrounding tissues and expression of Ki-67, p53, and bcl-2. One patient with infiltration to the surrounding tissue was diagnosed as intermediate-grade malignancy, while the remaining 8 patients were diagnosed as low-grade malignancy. The BCAC cases included 7 patients with T2 and 2 patients with T1. Conservative resection was performed for all patients, and all cases are surviving cancer-free.
Conclusion: The malignancy of BCAC can be suspected before surgery based on symptoms/signs, diagnostic imaging, and FNAC. FSB enables the diagnosis of not only malignancy but also the grade of malignancy, which may help determine the appropriate surgical resection. Although all 9 patients with BCAC are surviving free from cancer, a long-term follow-up is warranted.
Keywords: Basal cell adenocarcinoma; Basal cell adenoma; Fine-needle aspiration cytology; Frozen section biopsy; Parotid carcinoma.
Copyright © 2020. Published by Elsevier B.V.