Oncocytic papillary cystadenoma of parotid gland: A diagnostic challenge on fine‐needle aspiration cytology

Dear Dr. Bedrossian: Oncocytic papillary cystadenomas (OPC) of the head and neck are rare tumors. They have been reported in accessory tear glands, minor salivary glands of buccal mucosa, soft palate and lip, nasopharynx, larynx, and infrequently in parotid glands. The lesion tends to occur more frequently in women; most patients are older then 50 years of age. The usual presentation is an asymptomatic mass present for several years before diagnosis. The biological behavior of this tumor is similar to that of Warthin’s tumor. Recurrences are unusual and probably represent mutifocality. The cytological features of this lesion have not been well documented in literature, and histopathology is mandatory to arrive at a final diagnosis. A 75-year-old male presented with a slightly painful swelling in right upper posterior cervical region, just below the angle of mandible, slowly increasing in size over a year. On examination, the swelling measured 2.5 cm in diameter, was firm, slightly tender, and mobile. The patient gave the history of root abscess in the 2nd right lower molar tooth and took antibiotics for it off and on. He was referred for fine-needle aspiration (FNA) with a clinical diagnosis of lymphadenitis. FNA was performed on two occasions at an interval of 1 week. Both times whitish turbid fluid was aspirated. The smears were air dried for Giemsa staining and wet fixed for Papanicolaou (Pap) staining. Smears from the first aspirate revealed a necrotic inflammatory background with presence of scattered atypical squamous cells including an occasional orangeophilic cell with pyknotic nucleus, tadpole and fibre cells on Pap stain (Fig. 1). The differential diagnoses considered were cystic squamous cell carcinoma, branchial cyst, infracted pleomorphic adenoma, and infracted Warthin’s Tumor. As there was no obvious primary malignancy and the patient was clinically well preserved, a second FNA from a different site was advised after a course of antibiotics. This aspirate showed a different picture, comprising of many vacuolated cells, some containing pinkish mucinous material and some with a signet ring appearance (Fig. 2). In addition, there were a few atypical squamous cells and an occasional multinucleated giant cell with atypical hyperchromatic nuclei against a mucoid inflammatory background (Fig. 3). The differential diagnoses offered included mucoepidermoid tumor, Warthin’s tumor, and cystic adenosquamous carcinoma. The CT scan of head and neck region performed at this time revealed a circumscribed swelling in the lower pole of parotid gland. The swelling was excised under local anaesthesia and on histopathology; a diagnosis of oncocytic papillary cystadenoma of parotid gland was returned (Fig. 4). There were no mucin-containing cells or features of squamous malignancy on histopathology sections. Because of these noncorrelating features on histology, the FNA smears were reviewed. No characteristic oncocytic cells or papillary structures were found in the smears even on review. The atypical squamous cells in a necrotic background seen on first FNA which prompted us to consider a presumptive diagnosis of cystic squamous cell carcinoma probably represented degenerative atypia in metaplastic squamous cells. Else, the oncocytic cells shed in the cyst fluid might have assumed squamoid appearance because of partial degeneration and stained deep blue on Giemsa; these cells were misinterpreted as atypical squamous cells (Fig. 5). In fact, an occasional elongated, columnar cell was identified on careful review of cytology smears, which appeared morphologically similar to the oncocytic cells shed off from the papillae in histology sections (Fig. 5, inset). Whether, these oncocytic cells *Correspondence to: Sanjay Gupta, M.D., Division of Cytopathology, Institute of Cytology & Preventive Oncology (ICMR), I-7 Sector 39, Noida 201301, India. E-mail: sanjaydr17@hotmail.com Received 22 February 2010; Accepted 14 June 2010 DOI 10.1002/dc.21501 Published online 2 November 2010 in Wiley Online Library (wileyonlinelibrary.com).