Sclerosing Polycystic Adenosis of Salivary Glands: A Review with Some Emphasis on Intraductal Epithelial Proliferations

Abstract

Sclerosing polycystic adenosis (SPA) is a rare condition of salivary glands. The most common site is the parotid gland (80 % of cases). SPA shows no gender predilection and occurs over a wide age spectrum (9-84 years). SPA is mostly unifocal, but may rarely be multifocal. Histologically, SPA are sharply circumscribed mostly unencapsulated lesions composed of acinar and ductal components with variable cytomorphological characteristics, including foamy, vacuolated, apocrine, mucous, clear/ballooned, squamous, columnar and oncocyte-like cells. Characteristic for SPA is the presence of large acinar cells with abundant eosinophilic cytoplasmic granules. The stroma is densely collagenized, frequently harbouring a variably intense chronic inflammatory infiltrate and may contain fat. Rarely the stroma is myxoid. Some degree of intraductal epithelial proliferations have been reported in at least 50 % of cases. The proportion of cases with epithelial proliferations that fulfill criteria for high-grade ductal carcinoma in-situ is \10 %. Immunohistochemically, both ductal and acinar cells are positive for broad spectrum cytokeratins. There is variable immunoreactivity for epithelial membrane antigen and S-100 protein. CEA, p53 and HER2 is reportedly negative. Gross cystic disease fluid protein-15 is strongly expressed in the acinar component. There is consistent but variable expression of estrogen and progesterone receptors. The proliferative index (Ki-67) is low (1-2 %) in the benign (acinar and ductal) components. Using HUMARA methodology (non-random inactivation of X-chromosomes), six cases with atypical epithelial proliferations have been shown to be clonal processes. Recurrences have been reported in up to 19 % of cases.

Newly described salivary gland tumors

“…Patients range in age from 9 to 84 years with a slight female predominance; the mean age at presentation is around 40 years. 80 Most tumors involve the major salivary glands, in particular the parotid gland and less commonly, the submandibular gland. 76 Only rare definite cases have been reported in the minor salivary glands of the oral cavity, 59,64,65,68 sinonasal tract 75 and in the lacrimal gland.…”

Salivary Gland Tumor “Wishes” to Add to the Next WHO Tumor Classification: Sclerosing Polycystic Adenosis, Mammary Analogue Secretory Carcinoma, Cribriform Adenocarcinoma of the Tongue and Other Sites, and Mucinous Variant of Myoepithelioma

“…To date, there are 63 cases reported [1][2][3][4][5][6][7][8][9][10][11][12][13]. Patients range in age from 9 to 84 years with a male to female ratio of 27:36.…”

Fine-Needle Aspiration Cytology of Cellular Basaloid Neoplasms of the Salivary Gland

“…However, cytoplasm is typically somewhat more abundant and granular than other basaloid salivary tumors, even when acinar and/or apocrine differentiation is not present. 2,16 Occasionally, basaloid adnexal tumors of the deep dermis of the skin of the face or neck may be mistaken for salivary gland origin on physical examination or radiographically. Squamous differentiation or the presence of anucleate squamous cells is often seen in basaloid adnexal tumors on FNA (eg, pilomatrixoma, trichilemmal cyst), which can provide a hint in such cases.…”