Sunila Hussain, Nadia Naseem, Rabia Anjum, Ihtesham-ud din Qureshi, Ah Nagi.
Histopathological spectrum of pleomorphic adenoma reported at tertiary care hospitals in Lahore.
Pak Oral Dental J Jan ;36(4):565-71.

Pleomorphic adenoma (PA) is reported to be commonest benign neoplasm of salivary glands in Pakistan constituting 80-90% of all benign salivary gland tumours. Owing to the high prevalence and scarcity of local data in relation to the spectrum of its histological features, this study was designed to describe the various morphological patterns of this tumour with potential diagnostic pitfalls. This descriptive study was conducted at the Department of Morbid Anatomy and Histopathology/ Oral Pathology, University of Health Sciences Lahore, Pakistan. Paraffin embedded blocks and detailed clinical data of 63 cases of pleomorphic adenoma reported at local tertiary care hospitals from Jan. 2013 to Sep. 2015 was retrieved. The histologic diagnosis was made on Hematoxylin and Eosin staining. The tumours were classified into classic, cell-rich and stroma-rich subtypes. The tumoral parenchyma was observed according to the presence of cuboidal, spindle, stellate, plasmacytoid & squamous. The epithelial architectural pattern was studied with respect to the ducts, trabeculae, solid nests while mesenchymal component was divided into myxoid, chondroid and chondromyxoid elements. Unusual epithelial and /or stromal differentiations were observed and reported accordingly. The most frequently observed age group of the patients was the 2nd and 3rd decades (43%) with mean age of 35.57 (± 16.993). Females reported more frequently (69.9%) than males (30.1%) (F: M ratio= 2.3:1). Parotid gland (62%) was the commonest site involved followed by submandibular gland (19%) and palate (12.6%). Histologically, classic variant (46%) was the commonest subtype followed by cell-rich (32%) and stroma-rich (22%) types. Cuboidal (81%) and spindle (62%) cells dominated most cases. Ducts (92%) and trabeculae (22.2%) were the most common epithelial patterns seen while myxoid (90%) and chondroid (55.5%) were the most frequently encountered mesenchymal patterns. Unusual patterns of lipomatous (6.3%), osteoid (17.4%) and extensive squamous differentiation with keratin pearl formation were also observed (20.6%). Pleomorphic adenoma occurs in a younger age group in Pakistani population with a female predilection. The most favoured site for PA is the parotid gland while the commonest minor salivary gland site is palate. Classic variant of PA is the commonest subtype followed by cell-rich variant. A variety of histological patterns can be encountered in pleomorphic adenoma which may cause diagnostic pitfalls and thus have serious therapeutic and prognostic implications. Hence there is a dire need for meticulous approach in reporting these lesions.

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