Salivary Adenoid Cystic Carcinoma: A Clinicohistologic Study in a Nigerian Tertiary Institution

Abstract

Background: Adenoid cystic carcinoma (ADCC) is a slow-growing salivary gland tumor with high recurrence and mortality rates. Histologic variants present variable aggression. This has not been investigated in Nigeria. This study aimed to investigate association of histologic variants with clinical aggression in Nigerian cases. Patients and Methods: Fifty‑nine ADCC from 363 salivary gland tumors were selected from the departmental oral biopsy archives. Clinical data were retrieved, and hematoxylin and eosin sections were reviewed for confirmation and categorization into solid, cribriform, and tubular (modified Perzin, Spiro and van Weert systems). Estimated mean tumor growth rates (EMTGRs) were computed and matched with histologic variants. Statistical analysis was Chi-square, Kruskal–Wallis, and Mann–Whitney’s test. P value was ≤0.05. Statistical package was SPSS. Results: Age ranged between 7 and 83 years (mean 49.2 ± 16.8 years). About 75.1% occurred in the 4th–6th decade (p = 0.02). Most common histologic variant was predominantly cribriform no solid (PCNS) pattern (40.7%). In major salivary glands, there was association between histologic variant and EMTGR (p = 0.025). PCNS had the highest EMTGR (0.840) followed by predominantly solid (PS) (EMTGR, 0.744). These were significantly higher than predominantly tubular no solid (PTNS) (EMTGR, 0.442) and predominantly tubular 30% solid (EMTGR, 0.115). In minor glands, there was also association between histologic variants and EMTGR (p = 0.017). However, the highest EMTGR (0.509) occurred in PTNS followed by PCNS (0.428). These were significantly higher than PS (0.259) with the least EMTGR. Conclusion: Trend of clinical aggression of histological variants based on EMTGR of ADCC varies depending on the type of salivary gland (major vs. minor).