DOG1, alpha-amylase and p63 expression in acinic cell carcinoma of salivary gland; immunohistochemical, clinical and radiological study

Introduction: Identification of serous acinar differentiation is the basic step for the diagnosis of acinic cell carcinoma (ACC). α-amylase was described to be specific for normal acinar cell but its affinity to malignant counterpart is being contentious. Recently discovered marker anoctamin (DOG1) specific for diagnosis of GISTs has been reported for its efficacy to stain the malignant acinar cells and so, it is being of value in ACC diagnosis. On the other hand, negativity of acinar cells to basal cell marker as p63 will give more pronouncement to ACC diagnosis. Objectives: The study were designed to scrutinize the expression of recent marker DOG1 versus α-amylase in ACC diagnosis. Also to correlate between clinical, radiological, histopathological and immunohistochemical findings in ACC cases. Material and methods: Fourteen cases of ACC were obtained and stained immunohistochemically for DOG1, α-amylase and p63. Clinical data as well as radiological findings were obtained from the patients’ file to form correlation with immunostaining results. Results: All ACCs (100%) revealed positivity toward DOG1 staining, 6 (44%) cases out of 14 showed α-amylase positivity, and 1 case (7%) showed focal positivity for p63. No significant correlation was found between clinical, radiological and immunostaining results. Significant correlation was obtained between results of DOG1 and α-amylase with p-value=0.034, also significant correlation was obtained between DOG1 and p63 with p-value=0.02. On the other hand, no significant correlation was obtained between results of both α-amylase and p63 with p-value=0.546. Conclusion: DOG1 has a higher efficacy in the diagnosis of ACC than α-amylase and must be used especially for cases with some conflicts as poor tissue sampling or suspicious cases with other carcinomas especially with carcinomas of clear cell features or having a vacuolated cytoplasm.