LETTER TO EDITOR
Year : 2010 | Volume
: 53 | Issue : 1 | Page : 166--167
Polymorphous low-grade adenocarcinoma of left parotid gland
Ibrahim Gelincik1, Irfan Bayram2, Hakan Cankaya3,
1 Department of Pathology, Region Education and Research Hospital, Erzurum, Turkey
2 Department of Pathology, 100. Yil University, Faculty of Medicine, Van, Turkey
3 Department of Otorhinolaryngology, 100. Yil University, Faculty of Medicine, Van, Turkey
Department of Pathology, Region Education and Research Hospital, Erzurum
|How to cite this article:|
Gelincik I, Bayram I, Cankaya H. Polymorphous low-grade adenocarcinoma of left parotid gland.Indian J Pathol Microbiol 2010;53:166-167
|How to cite this URL:|
Gelincik I, Bayram I, Cankaya H. Polymorphous low-grade adenocarcinoma of left parotid gland. Indian J Pathol Microbiol [serial online] 2010 [cited 2021 Jan 25 ];53:166-167
Available from: https://www.ijpmonline.org/text.asp?2010/53/1/166/59217
Apropos the article by Arathi and Bage  published in your journal; we encountered a similar case which we would like to report.
Polymorphous low grade adenocarcinoma (PLGA) is a rare salivary gland malignant tumor which is less aggressive and originating from the intercalated duct. We report a case of PLGA of the left parotid gland.
A 35-year-old male presented with an asymptomatic painless left mass in the preauricular region which gradually increased in size over a period of 10 years. Ultrasound examination revealed a 3.7x3.1x2.3 cm multicystic tumoral mass in the left parotid gland. Macroscopically, the resected mass was well circumscribed, partly encapsulated, and measured 4x3x2.5 cm. The cut surface had yellow-brown solid areas intermingled with cystic spaces [Figure 1]. Microscopically, the lesion was composed of round to oval isomorphic cells with bland, minimally hyper chromatic oval nuclei, occasional nucleoli, and scant mitotic figures [Figure 2]a. These cells formed diverse patterns including papillary-cystic [Figure 2]b, cribriform [Figure 2]c and lobular, with predominance of the first two types. Isolated tumor cells were scattered in hyalinized material that resembled basal lamina. Neither perineural invasion nor vascular permeation was seen in the studied sections. Immunohistochemically, S-100 protein [Figure 3]a, and vimentin [Figure 3]b were positive but smooth muscle actin (SMA) and glial fibrillary acidic protein (GFAP) was negative in tumor cells. Ki67 + cells were determined by counting at least 1000 tumor cells. Proliferative activity assessed with the Ki67 labeling index was three per cent [Figure 3]c.
PLGA is characterized by its cytological uniformity with histomorphologic diversity, infiltrative growth and low metastatic potential. ,, Distinguishing PLGA from other tumors such as intra-oral salivary gland carcinoma arising within a pre-existing pleomorphic adenoma and adenoid cystic carcinoma is important because these tumors have much worse prognosis. In addition, they are more likely to recur, metastasize to regional and distant sites. 
Unlike PLGA, pleomorphic adenoma is nearly always circumscribed and composed of proliferating stromal, epithelial and myoepithelial cells. In the present case, smooth muscle actin (SMA) was immunohistochemically negative in tumor cells.
Myxoid tissue is present both in PLGA and pleomorphic adenoma. In addition, the myxochondroid and chondroid areas present in pleomorphic adenoma are not evident in PLGA. In the present case, there were no myxochondroid and chondroid areas.
The distinction between PLGA and adenoid cystic carcinoma is based primarily on cytologic features. Cells in PLGA are cuboidal or columnar. More over, they have vesicular nuclei, and often conspicuous eosinophilic cytoplasm without the basaloid features characteristic of adenoid cystic carcinoma. Papillary and fascicular growth patterns are extremely rare in adenoid cystic carcinoma. In the present case, cells were cuboidal and columnar. In addition, papillary growth patterns were present.
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