Lymphoid cell rich fine-needle aspirations of the salivary gland: What is the risk of malignancy?

Abstract

Objectives: Lymphoid cell rich fine-needle aspirations (FNAs) of the salivary glands pose a diagnostic dilemma, with a wide range of differential diagnoses that include several benign and malignant entities. There is limited literature regarding the entities that are commonly encountered in this situation. Our goal was to characterize the surgical outcome in these cases and to evaluate the risk of malignancy. Material and Methods: This is a retrospective study at a tertiary care institution. Our database was queried over a 10-year period. FNAs yielding a prominent population of well-visualized lymphoid cells were included in the study. Only cases with surgical follow-up were evaluated. FNAs with epithelial cells, diagnostic features of any entity (such as granulomas or chondromyxoid stroma), history of metastatic malignancy, or scant cellularity were excluded from the study. Lymphoid cells were classified as atypical according to morphologic findings (monomorphism, irregular nuclear contours, and abnormal chromatin patterns). Statistical analysis was performed. Results: Of the 224 lymphoid cell rich FNAs identified, 29 (28%) had surgical follow-up in our data records. Twenty-two were from the parotid and seven from the submandibular gland. Ten cases (35%) were non-neoplastic (benign lymphoepithelial cyst [n = 4], reactive lymph node [n = 5] and chronic sialadenitis [n = 1]). Benign epithelial neoplasms including pleomorphic adenoma (n = 2) and Warthin’s tumor (n = 1) were identified in 10% of the cases. One case with non-atypical lymphocytes proved to be a mucoepidermoid carcinoma (n = 1). Lymphomas were detected in 52% (n = 15). Of note, none of these patients had a history of lymphoid malignancy. 8/15 were low-grade and 7/15 were high-grade lymphoma. Most of these cases (11/15) had atypical lymphocytes on FNA. Ancillary studies were available in a few cases and supportive of the diagnosis of lymphoma, including cell block and immunohistochemistry (n = 7, 47%), flow cytometry (n = 3, 27%), and clonality polymerase chain reaction (PCR) (n = 1; 7%). Most of these were performed in cases with atypical lymphocytes. In cases with non-atypical lymphocytes, five cases were malignant on surgical excision (5/17). Morphology on FNA had a specificity of 92% for malignancy and sensitivity of 69%. The positive predictive value on FNA of atypical lymphocytes for malignancy was 92%. Conclusion: Lymphoid cell rich FNAs carry a 52% incidence rate lymphoma in our small study population. Specificity of FNA for malignancy is high (92%) and lymphocyte atypia is a strong predictor of malignancy. Ancillary studies may be of added value in FNAs with non-atypical lymphoid cells. FNA has a valuable role in triaging lymphoid lesions of the salivary glands.