Cytological features of carcinoma ex pleomorphic adenoma of the salivary glands: A diagnostic challenge

Abstract

Carcinoma ex pleomorphic adenoma (CXPA) of the salivary glands is a relatively rare carcinoma. The detection rate of the carcinoma component in the cytological specimens is not high and may be challenging in cytological examination. The purpose of the present study was to analyze the cytological specimens of CXPA with emphasis on the detection of the carcinoma component. We reviewed the cytological characteristics of patients histopathologically diagnosed with CXPA who underwent preoperative cytological examination. Of the 10 patients enrolled in the study, 8 had tumors located in the parotid gland, and 2 in the submandibular gland. A review of the cytological specimens revealed the presence of the carcinoma component in all 10 cases and the pleomorphic adenoma (PA) component in 6 cases, although initial cytodiagnosis detected the carcinoma component in 8 cases. The cytological feature of this component was the presence of variable‐sized clusters of polygonal cells with relatively rich cytoplasm and large round to oval nuclei in a necrotic background. Interestingly, carcinoma cells mixed with the PA component were also present. On histopathological analysis, 7 cases were intracapsular, and the remaining 3 cases were widely invasive CXPA. Further, 9 cases had salivary duct carcinoma as carcinoma component. In conclusion, these findings show that careful detection of the carcinoma cells, particularly within the PA component, is crucial for early detection of CXPA, and the presence of necrosis might help with the detection of the carcinoma component.

Spontaneous infarction of pleomorphic adenoma of the parotid gland: A case report

“…Presence of atypical metaplastic squamous cells positive for p40 in a necrotic background was characteristic cytological feature of infarcted PA. Although a necrotic background is an important indication of malignancy in the cytological diagnosis of salivary gland tumours (11), the presence of atypical metaplastic squamous cells in a necrotic background does not directly indicate malignant diagnosis. Though cytological diagnosis of infarcted PA is extremely difficult, pathologists and cytopathologists must consider that atypical metaplastic squamous cells may be present in benign salivary gland tumours, including infarcted PA.…”

The accurate cytological diagnosis of salivary carcinoma ex pleomorphic adenoma may be hampered by myoepithelial differentiation

“…Until 1999, the FNA findings in only 41 cases of carcinoma ex pleomorphic adenoma had been reported 3 . Since then, 33 additional cases with modern classification criteria have been retrieved from the literature 2‐4,9,16,17 . Of these, 19 showed non‐MED and 14 (including our case) showed MED (Table 1).…”

“…The cytology of myoepithelial carcinoma is challenging due to the variable cytomorphology with spindled, plasmacytoid, epitheloid or clear cell patterns 7 . Few reports describe the cytomorphological features in myoepithelial carcinoma or myoepithelial carcinoma ex pleomorphic adenoma 2‐4,8‐11 . Usually these studies encountered difficulties in recognising the malignant nature of myoepithelial carcinoma.…”

“…Only a limited number of reports describe fine needle aspiration (FNA) in the diagnosis of carcinoma ex pleomorphic adenoma 1,2 . The accuracy of cytological diagnosis is low in carcinoma ex pleomorphic adenoma, and depends on the growth pattern as well as on the histological category of carcinoma 2,3 .…”

“…Only a limited number of reports describe fine needle aspiration (FNA) in the diagnosis of carcinoma ex pleomorphic adenoma 1,2 . The accuracy of cytological diagnosis is low in carcinoma ex pleomorphic adenoma, and depends on the growth pattern as well as on the histological category of carcinoma 2,3 . There is an increased risk of a false‐negative FNA diagnosis on low‐grade encapsulated carcinomas compared to infiltrative high‐grade carcinomas 1‐3 .…”