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 Table of Contents  
Year : 2018  |  Volume : 2  |  Issue : 3  |  Page : 55-57

Basal cell adenoma of the buccal mucosa masquerading as irritation fibroma: A rare case report

1 Department of Oral Medicine and Radiology, Institute of Dental Sciences, SOA University, Bhubaneswar, Odisha, India
2 Department of Oral Pathology and Microbiology, Institute of Dental Sciences, SOA University, Bhubaneswar, Odisha, India

Date of Web Publication21-Sep-2018

Correspondence Address:
Dr. Ruchi Bhuyan
Department of Oral Pathology and Microbiology, Institute of Dental Sciences, SOA University, Bhubaneswar, Odisha
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/oji.oji_26_18

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Basal cell adenoma (BCA) is an uncommon benign epithelial neoplasm of salivary gland consisting of 1%–2% of all salivary gland epithelial tumors. Frequently, these tumors occur in major salivary glands, mostly in the parotid gland. These tumors rarely occur in minor salivary gland. We report a case of BCA in a 54-year-old male patient having a growth in the left upper gingivobuccal sulcus at maxillary tuberosity region with respect to 27 and 28, which was clinically presented as irritation fibroma and was histologically diagnosed as BCA. The dilemma in diagnosis of this rare lesion, histologic paradox, and insufficient descriptive studies has directed us to present this case to serve as a guide for clinicians for proper clinicopathological and radiological analysis of such lesions.

Keywords: Basal cell adenoma, irritation fibroma, minor salivary gland, upper gingivobuccal sulcus

How to cite this article:
Das P, Niyogi S, Bhuyan SK, Bhuyan R. Basal cell adenoma of the buccal mucosa masquerading as irritation fibroma: A rare case report. Oncol J India 2018;2:55-7

How to cite this URL:
Das P, Niyogi S, Bhuyan SK, Bhuyan R. Basal cell adenoma of the buccal mucosa masquerading as irritation fibroma: A rare case report. Oncol J India [serial online] 2018 [cited 2019 Jul 18];2:55-7. Available from: http://www.ojionline.org/text.asp?2018/2/3/55/241842

  Introduction Top

Salivary gland neoplasms constitute <1% of all tumors and 3%–5% of all head-and-neck tumors. Minor salivary gland tumors are infrequent consisting 10%–15% of all salivary gland neoplasms and most of the cases are located in the palate (50%), followed by lips (15%), cheek mucosa (12%), tongue (5%), and floor of the mouth (5%).[1],[2]

Basal cell adenoma (BCA) of the salivary gland is an uncommon type of benign monomorphic adenoma with high recurrence rate but good prognosis. Nearly 1%–2% of the salivary gland epithelial tumors have been reported as BCA. Majority of BCA cases arise in the major salivary glands, but minor salivary gland origin is rare.[3] Histologically, BCA has four characteristic patterns such as solid, trabecular, tubular, and membranous.[4] We report BCA in a 54-year-old male presenting as an asymptomatic swelling over the left side of the upper gingivobuccal sulcus and alveolar mucosa region.

  Case Report Top

A 54-year-old male presented with chief complaint of mild pain and swelling on the posterior aspect of left upper gum for 2 months. The general clinical examination was unremarkable with no history of weight loss, diabetes, hypertension, tuberculosis, or some other systemic diseases.

Intraoral examination showed an asymptomatic swelling over the left upper gingivobuccal sulcus extending to the buccal mucosa with respect to 27 and 28 and extending posteriorly in the tuberosity region with respect to 28. The swelling was ovoid in shape, measuring about 1.5 cm × 2 cm, with well-circumscribed borders extending from the mesial aspect of 27 to the distal aspect of 28 [Figure 1]. The mucosa over the swelling was pinkish-red in color and stretched. The swelling had an inflammatory erythematous appearance, and posteriorly, the growth of tissue appeared keratinized due to repeated trauma from lower 37.
Figure 1: A growth of size 1.5 cm × 2 cm located at the left maxillary tuberosity region

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The swelling was nontender, soft in consistency, compressible, and erythematous in appearance. The growth posterior to 28 is sessile, soft, smooth surface, and nontender. Bleeding on probing was present with respect to 28. The mucosa over the swelling was freely mobile. No other lymph nodes or masses were palpable in the head-and-neck region.

With the above clinical features of the lesion and the site of occurrence, we provisionally diagnosed the case as irritation fibroma.

Radiological analysis was made using intraoral periapical radiograph which showed no bony involvement. Contrast-enhanced computed tomography (CECT) scan of face and neck [Figure 2] revealed a soft-tissue density mass of 22 mm × 20 mm in the left maxillary tuberosity with mild erosion of adjacent maxilla and the lesion also involves posterior part of upper gingivobuccal fold with no definite infiltration of pterygoid muscle seen. Incisional biopsy was done. Microscopic examination of the specimen showed islands of dark staining basaloid cells arranged in the form of trabecular pattern. Trabecular area shows narrow cord-like basaloid cells, and small, round duct-like structure in the fibrous stroma, suggestive of trabecular variant of BCA [Figure 3].
Figure 2: A soft-tissue density mass of 22 mm × 20 mm in the left maxillary tuberosity

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Figure 3: Clusters of basaloid cells with peripheral palisading and absence of stromal invasion (H and E stain, ×100)

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After confirmation of the diagnosis, wide local excision with upper alveolectomy was done and histopathological examination showed similar features of BCA without the involvement of upper alveolus. The patient is on regular follow-up without any recurrence of the disease for the past 6 months of the surgery.

  Discussion Top

Kleinsasser and Klein designated the term BCA in 1967 and established it as a separate clinical and pathological entity and thus it was categorized as a type of monomorphic adenoma.[3] BCA accounts for 54% of monomorphic adenomas and 1%–3% of major salivary gland tumors with 7.5% incidence of primary epithelial parotid gland tumors.[5] Majority of the cases reported in the sixth decade of life with the mean age of presentation at 57.7 years, and there is a slight female gender predilection for the tumor, whereas the membranous variant has equal gender predilection.[3],[6]

The most common site of occurrence is the superficial lobe of parotid gland, while minor salivary gland is a rare location. Upper lip, buccal mucosa, lower lip, and palate are the sites for minor salivary gland origin of BCA.[3],[5] In our case, the tumor was located in the minor salivary gland of the buccal mucosa adjacent to the third molar region occurring in a 54-year-old male patient which is a rare presentation.

Majority of the cases present as a painless slow-growing mass not exceeding 3 cm in greatest diameter and there is no regional lymph node involvement, calcification, or cystic component present within the tumor.[5],[7] Clinically, BCA may resemble a mucocele of the oral mucosa, but the mucocele usually appears in the lower lip of young people, whereas BCA appears in the upper lip of the elderly.[4] In our case, the mass was located in the left upper gingivobuccal sulcus, ovoid in shape with smooth surface, measuring 2 cm in greatest diameter, and it is sessile, freely mobile, and soft in consistency. Clinically, we suspect the case as irritation fibroma which is the most common oral fibrous tumor-like growth representing reactive focal fibrous hyperplasia due to trauma or local irritation and the lesion appears as a sessile or pedunculated nodule, round to ovoid in shape with smooth surface, commonly located on the buccal mucosa along the plane of occlusion of the maxillary and mandibular teeth, and the diameter of the lesion may vary from 1 to 2 cm. Pyogenic granuloma, peripheral ossifying fibroma, metastatic cancer, fibroma, hyperplastic gingival inflammation, hemangioma, and angiosarcoma are the common differential diagnosis for the irritation fibroma.[8] However, our case ís pathologically confirmed as BCA.

Gross examination of BCA shows a well-circumscribed, encapsulated, yellowish-white tumor, soft to firm in consistency, and highly vascular in nature, and cut surface shows a uniform lesion of gray-white or tan-white color.[5]

Histopathology is the gold standard for the diagnosis of BCA. The presence of uniform and regular basaloid cells in the stroma is the histological characteristic feature of BCA, and these cells are surrounded by a dense fibrous connective tissue capsule. The BCA has two morphologic forms of cells such as basaloid cell and luminal duct cells. The first cell group is small cells having scanty cytoplasm with deeply basophilic rounded nuclei and is peripherally located in a palisading arrangement. The other group is large cells having eosinophilic cytoplasm with an ovoid pale staining nucleus and is centrally located. There is a presence of demarcation between the neoplastic cells and surrounding structure.[9]

Pan-CK, CK 5/6, and S100 may be expressed in BCA. Positivity of S100 and Pan CK in BCA indicates their relation to myoepithelial cells, but some authors suggest the independence of these markers to BCA.[4],[10]

Majority of pleomorphic adenoma and malignant salivary gland tumor show increased enhancement in delayed phases of computed tomography (CT). The patient's age and attenuation on unenhanced- and enhanced-CT help to differentiate BCA from pleomorphic adenoma.[5]

Surgical excision in the form of a superficial or total parotidectomy is the primary treatment of BCA in which parotid affectation exists, whereas extracapsular excision is performed if there is affectation of minor salivary glands in the oral mucosa. Due to possible unencapsulated nature of BCA, adequate local excision should be the best treatment in comparison to enucleation. The capsule should not be disrupted to minimize the risk of recurrence.

Due to the multifocal and multinodular growth pattern, membranous type has high recurrence rate (25%–37%) in comparison to the solid, trabecular, and tubular variants where it is almost nil. Malignant transformation is rare among BCA but more common in the membranous type (around 4.3%).[4]

In summary, BCA is a rare benign epithelial tumor of the minor salivary gland. The present case was clinically suspected as irritational fibroma of the buccal mucosa but histopathologically diagnosed as BCA highlighting the possibility of BCA in minor salivary glands during clinical practice.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Kulkarni HS, Kulkarni GH, Khaji SI, Iqbal E, Biradar JM. Monomorphic adenoma: A rare benign neoplasm of the minor salivary gland: Case report and review of literature. J Dent Allied Sci 2014;3:108-10.  Back to cited text no. 1
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Yih WY, Kratochvil FJ, Stewart JC. Intraoral minor salivary gland neoplasms: Review of 213 cases. J Oral Maxillofac Surg 2005;63:805-10.  Back to cited text no. 2
Yadav AB, Narwal A, Devi A, Kumar S, Yadav SK. Basal cell adenoma of palate, a rare occurrence with review of literature. J Dent (Shiraz) 2015;16:291-5.  Back to cited text no. 3
Bhagat Singh AD, Majumdar S, Ghosh AK, Gandi L, Choudaha N, Sharma I, et al. Basal cell adenoma-clinicopathological, immunohistochemical analysis and surgical considerations of a rare salivary gland tumor with review of literature. Niger J Surg 2015;21:31-4.  Back to cited text no. 4
Gupta N, Jadhav K, Ahmed MB, Amberkar VS. Basal cell adenoma in a relatively rare site. J Oral Maxillofac Pathol 2009;13:101-4.  Back to cited text no. 5
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Siddaraju A, Giraddi GB, Hemamythily P, Bhatt G, Nayaknur VA. Basal cell adenoma of palate – Report of a rare lesion. Arch Oral Sci Res 2013;3:51-5.  Back to cited text no. 6
Kanaujia SK, Singh A, Nautiyal S, Ashutosh K. Basal cell adenoma of parotid gland: Case report and review of literature. Indian J Otolaryngol Head Neck Surg 2015;67:430-3.  Back to cited text no. 7
Kolte AP, Kolte RA, Shrirao TS. Focal fibrous overgrowths: A case series and review of literature. Contemp Clin Dent 2010;1:271-4.  Back to cited text no. 8
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Kim CW, Kim SG. Basal cell adenoma misdiagnosed as an adenoid cystic carcinoma in the parotid gland. J Korean Assoc Oral Maxillofac Surg 2012;38:314-7.  Back to cited text no. 9
Chiu NC, Wu HM, Chou YH, Li WY, Chiou YY, Guo WY, et al. Basal cell adenoma versus pleomorphic adenoma of the parotid gland: CT findings. AJR Am J Roentgenol 2007;189:W254-61.  Back to cited text no. 10


  [Figure 1], [Figure 2], [Figure 3]


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