SYNCHRONOUS OCCURRENCE OF ACINIC CELL CARCINOMA OF SOFT PALATE AND SQUAMOUS CELL CARCINOMA OF LUNG: A CASE REPORT

Abstract

Acinic cell carcinoma (AcCC) is a low-grade malignant salivary neoplasm and constitutes approximately 6% to 8% of all salivary gland neoplasms. Although it has low-grade histology, AcCC has a significant tendency to metastasize. We report the first case of AcCC in our facility of a 74-year-old man who presented with a slow-growing mass on the left soft palate. A diagnosis of AcCC was made based on the characteristic histologic features of an infiltrative tumor of large polygonal cells with dark, round, eccentric nuclei and having PAS-D-positive basophilic granules along with immunohistochemical findings positive for CK7. The presence of intravascular invasion was evident. Concurrently, contrast-enhanced computed tomography of the thorax showed a suspicious nodule at the right upper lobe of the lung. Initially we suspected lung metastatic tumor based on the fact that AcCC has a significant tendency to metastasize to the lung and cervical lymph nodes. A wedge biopsy from the lung was done and revealed squamous cell carcinoma. Immunohistochemical studies on this tumor also showed different findings with immunopositivity with P63 and negativity for CK7. A probability of tumor metastasis to the lung was ruled out with the finding of a new primary tumor of the lung. AcCC can be misinterpreted due to its benign appearance, absence of malignant features, and histologic similarity to normal acinar cells. Pathologists should be aware and vigilant when reporting this entity. AcCC of the soft palate in this case is relatively rare and synchronous occurrence of other primary tumors makes it extremely unusual.