Original Contribution
Basal cell adenoma of salivary glands with a focal cribriform pattern: clinicopathologic and immunohistochemical study of 19 cases of a potential pitfall for diagnosis,☆☆,

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Abstract

Cribriform type of salivary basal cell adenoma (cBCA) is relatively rare and problematic in distinction from adenoid cystic carcinoma (AdCC). The aim of this study was to investigate the clinicopathology and immunoprofile of cBCA. Nineteen cases of cBCA with at least a 30% area of cribriform structure under microscope were analyzed by the description of their histopathologic and immunohistochemical features using the antibodies of matrix metalloproteinase-9 (MMP9), CK8&18, calponin, SMA, S100, P63, CD117, and laminin. The patients of cBCA ranged from 24 to 71 years with a distinct predilection for females (79%). The tumor was well-circumscribed and had no recurrent tendency after a local excision followed by a median of 67 months. Enhanced computed tomography (CT) showed that the tumor was rich in blood supply. Microscopically, it was mainly composed by the basaloid cells with the peripheral palisading. The cells around the cribriform pattern expressed P63 protein and had almost no immunoreactivity for calponin, SMA, S100, or CK8&18. The expression level of MMP9, laminin, and CD117 were significantly lower in cBCA than those in AdCC. Good circumscription, lack of infiltrative properties, and absence of MMP9, laminin, CD117, and myoepithelial marker (SMA, S100 and calponin) in the cells around the cribriform spaces, are the most reliable points for differential diagnosis of cBCA from AdCC.

Introduction

Basal cell adenoma (BCA) was first described by Kleinsasser and Klein in 1967 [1]. It’s a rare benign neoplasm characterized by the basaloid appearance of the tumor cells [2]. Nagao [3] first reported that some BCAs have cribriform patterns, pseudocysts of amorphous, basophilic material characteristic of adenoid cystic carcinoma (AdCC), which is a very difficult problem for differential diagnosis. Then Dardick [4] described this kind of adenoid cystic pattern or solid-cribriform type of BCA in 1992. Recently, 18 cases of cribriform BCA (cBCA) were reported having most of the clinicopathologic features of conventional BCA [5]. However, because of its rarity, more extensive review of this pattern is necessary.

The aims of this study were to analyze the clinicopathologic features and prognosis of cBCA with cribriform component and to compare the microscopic characteristics of cribriform pattern between cBCA and AdCC using matrix metalloproteinase-9 (MMP9), calponin, SMA, S100, P63, CK8&18, CD117 and laminin antibodies. It would allow clinicians to better understand the intrinsic quality of cBCA and choose an appropriate treatment.

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Materials and methods

The patients fulfilling the following criteria were included in our study: (i) a well-circumscribed tumor composed of the peripheral-palisading basaloid cells. (ii) cribriform patterns accounted for more than 30% in the tumor. Thus, a group of 19 cases from a total of 261 cases diagnosed as cBCA was retrieved from the files of Oral Pathology Department, Peking University School and Hospital of Stomatology from 1985 to 2012. All tissues were obtained in accordance with the protocols approved by

Clinical data

Nineteen cases of cBCA included 15 women and 4 men. The age at the time of diagnosis ranged from 24–71 years (average, 48 years). They all affected the parotid glands. The clinical symptom was only local swelling without pain. The enhanced CT revealed a well-defined solid mass that was rich in vascular (Fig. 1). The complete surgical removal with an extracapsular limit was performed. Grossly, the sizes of the tumors ranged from 0.8 to 5cm with the complete encapsulations (Fig. 2).

The follow-up

Discussion

Basal cell adenoma is the third most common of the benign parotid tumors, although its incidence is as low as accounting for 1% to 4% of all salivary gland tumors [7]. Nagao [3] reported that the incidence of BCA was 7.5% among 531 cases of primary epithelial tumors of the parotid gland, and adenoid cystic pattern accounted for 10% in BCA. Our data suggested that the percentage of cBCA was 7% (19/261). Basal cell adenoma can occur at any age but it happens most commonly in middle-aged and older

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Declaration of Conflicting Interests: The author declared no potential conflicts of interest with respect to the authorship and/or publication of this article.

Funding: The author received no financial support for the research and/or authorship of this article.

1

Contributed equally.

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