Cytological Variations and Diagnostic Challenges in Pleomorphic Adenomas

Abstract

BACKGROUNDPleomorphic Adenomas are the most common benign neoplasms of the salivary glands and are a diverse group of lesions. Most common site being major salivary glands, of which parotid gland constitutes 64% -80%. Fine Needle Aspiration Cytology (FNAC) of palpable salivary lesions is accepted as a useful preoperative diagnostic tool worldwide. Cytomorphological and histological diversity encountered in pleomorphic adenomas causes enormous diagnostic difficulty. Objective-The present study was done to evaluate the cytomorphological features of pleomorphic adenomas with an emphasis on differential diagnoses, challenges encountered during the diagnosis and addressing potential pitfalls. MATERIALS AND METHODSThis descriptive study was undertaken at the Upgraded Department of Pathology, Osmania General Hospital over a period of one (1) year and nine (9) months, that is from January 2016 to September 2017. Our study included 64 cases of pleomorphic adenoma diagnosed on fine needle aspiration cytology. Rapid Haematoxylin and eosin and Papanicolaou stains were used. Cytological smears were reviewed for nature of aspirate, patterns of epithelial component, type of mesenchymal matrix and degenerative changes like metaplastic and cystic changes. Radiological and histopathological correlation was available in all the cases. RESULTSA total number of 116 salivary gland lesions were aspirated, of which Pleomorphic adenomas were 64 (55.1%), chronic sialadenitis were 18 (15.5%), retention cysts were 12 (10.3%), sialadenosis were 8 (08-6.8%) and 3 cases of (03-2.5%) benign neoplasms-out of which two cases were Warthin's tumour and one case of monomorphic adenoma. Malignant lesions were 11 cases (9.4%). CONCLUSIONFNAC, though an accurate procedure for diagnosing pleomorphic adenoma, mostly poses diagnostic challenges because of the remarkable degree of cytomorphological diversity, for which pleomorphic adenoma earns a special distinction. Awareness of these variations is needed by the cytopathologist to avoid diagnostic errors.

Pleomorphic adenoma of the breast with cytologic atypia on cytopathology: A potential diagnostic pitfall and literature review

“…2,26,27 Usually, the distinction is readily made, except in PAs with a significant canalicular pattern (similar to cribriform), which will produce clumps of epithelial cells with balls of stroma, tubule formation, and myxoid stroma, mimicking adenoid cystic carcinoma. 28,29 This feature is found in approximately 5% of PA cases. 30 If the aspirate samples only this area, then the diagnosis may be missed.…”

“…PA has metachromatic and myxofibrillary stroma, whereas adenoid cystic carcinoma forms hyaline globules 2,26,27 . Usually, the distinction is readily made, except in PAs with a significant canalicular pattern (similar to cribriform), which will produce clumps of epithelial cells with balls of stroma, tubule formation, and myxoid stroma, mimicking adenoid cystic carcinoma 28,29 . This feature is found in approximately 5% of PA cases 30 .…”