Sclerosing Polycystic Adenosis of the Retromolar Pad Area: A Case Report

Sclerosing polycystic adenosis is a rare pathological lesion that affects salivary glands. The majority of cases involve the parotid and its occurrence in minor glands is exceedingly rare. Here, we report the first case of this lesion in the retromolar pad area and discuss its histological features and immunohistochemical reactivity with αSMA and Ki67 markers. A review of the literature on its immunohistochemical profile is also provided. Sclerosing polycystic adenosis has a diverse histomorphology and should be differentiated from other more important pathologic lesions. 1. Introduction To the best of our knowledge, 54 cases of sclerosing polycystic adenosis (SPA) of salivary glands have been reported. SPA characteristically arises in the major glands, and the majority of cases involve the parotid [1]. Some cases have also been reported in minor salivary glands of mucobuccal fold, hard palate, floor of mouth, and buccal mucosa [2, 3]. SPA has been reported in a wide age range from childhood to the eighth decade of life [1]. Here, we report the first case of SPA in the retromolar pad area. 2. Case Report A 60-year-old male presented with swelling in his retromolar pad area with two months’ duration. There was no tenderness or ulceration. Excisional biopsy of the lesion was performed and a well-circumscribed soft tissue lesion was excised. Histopathologic examination showed lobules of hyalinized connective tissue with epithelial components of ductal and acinar differentiation. Ductal structures formed variably sized cysts or they were packed as small ducts similar to the sclerosing adenosis of the breast. Ducts were lined by flattened to cuboidal epithelial cells and some cells had apocrine metaplasia. Mucous cells were frequently seen (Figures 1, 2, and 3). Periductal fibrosis with lamellar architecture was a common feature. Occasional hyaline globules were also present. Epithelial hyperplasia of ductal structures, formed solid nests, cribriform structures and intraductal anastomosing bridges. Few chronic inflammatory cells were infiltrated throughout the lesion. Figure 1: Large cystic spaces and cribriform structures were present throughout the lesion (×100). Figure 2: Apocrine metaplasia was evident throughout the lesion (×400). Figure 3: Mucous cells were frequently seen (×400). Immunohistochemical staining for αSMA and Ki-67 was performed. Myoepithelial cells, surrounding ductal elements, demonstrated immunoreactivity for αSMA (Figure 4). Immunohistochemical examination with Ki-67 revealed less than 1% positivity in lesional cells (Figure 5). The