Polymorphous low-grade adenocarcinoma

ABSTRACT

@#A 60-year-old woman with a 3-year history of a gingivoalveopalatal mass underwent an incision biopsy. Microscopically, the lesion centered in the stroma is infiltrative (Fig. 1) and architecturally diverse, having cystic (Fig. 2), linear or “Indian file” (Fig. 3), solid, and tubular (Fig. 4) patterns. The cells are uniform in size, round to oval, and have bland cytologic features, with vesicular nuclei and inconspicuous nucleoli (Figure 4). The clinical data and histomorphologic features characterized by architectural diversity yet cytologic blandness lead us to the diagnosis of polymorphous low-grade adenocarcinoma. Polymorphous low-grade adenocarcinoma (PLGA) is a malignant epithelial tumor characterized by cytologic uniformity, morphologic diversity, an infiltrative growth pattern, and low metastatic potential.1 It is the second most common intraoral malignant salivary gland tumor 1 following mucoepidermoid carcinoma. The tumor is found almost exclusively in minor salivary glands and is rare in extraoral locations, including major salivary glands.2 The tumor affects a wide age range (16 – 95 years; mean 60 years), with only 2 pediatric cases reported,1 and has a female predilection.3,4 It usually presents as a painless mass located within the oral cavity,3 60% of which are located in the palate.1 They are characteristically unencapsulated, although well-circumscribed.