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Year : 2021  |  Volume : 12  |  Issue : 1  |  Page : 44-47

Adenoid cystic carcinoma of the lower lip and buccal mucosa: A case report with review of literature

Department of Oral Pathology and Microbiology, SRM Dental College, Chennai, Tamil Nadu, India

Date of Submission23-Nov-2020
Date of Decision13-Jan-2021
Date of Acceptance22-Jan-2021
Date of Web Publication30-Mar-2021

Correspondence Address:
Dr. Amritha James
Department of Oral Pathology and Microbiology, SRM Dental College, Bharathi Salai, Ramapuram, Chennai - 600 089, Tamil Nadu
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/srmjrds.srmjrds_122_20

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Adenoid cystic carcinoma (AdCC) is an aggressive neoplasm that often carries a poor prognosis due to its high recurrence rate. Due to its indolent growth, it is often overlooked by the patients and early diagnosis is often challenging due to its deceptively benign clinical course. We report a case of AdCC in the lower lip and buccal mucosa of a patient with a review of the literature and added emphasis on their diagnosis and prognosis.

Keywords: Adenoid cystic carcinoma, buccal mucosa, cribriform, lower lip, prognosis

How to cite this article:
James A, Gunasekaran N, Shalini S G, Sherwin Samuel C S, Dolly A S, Shree Abiraami N S. Adenoid cystic carcinoma of the lower lip and buccal mucosa: A case report with review of literature. SRM J Res Dent Sci 2021;12:44-7

How to cite this URL:
James A, Gunasekaran N, Shalini S G, Sherwin Samuel C S, Dolly A S, Shree Abiraami N S. Adenoid cystic carcinoma of the lower lip and buccal mucosa: A case report with review of literature. SRM J Res Dent Sci [serial online] 2021 [cited 2022 Oct 3];12:44-7. Available from:

  Introduction Top

Adenoid cystic carcinoma (AdCC) is an aggressive malignant neoplasm of the salivary glands that account for about 10% of all malignant salivary gland neoplasms.[1] The exact etiology of the tumor remains unclear with many studies pointing toward a genetic mechanism.[2] The tumor most frequently arises within the minor salivary glands, but cases have also been reported in the major salivary glands and extra-oral sites such as the lacrimal glands, breast, vulva, and skin. The tumor most often exhibits an indolent growth and usually presents as a painless, asymptomatic lump which may or may not show surface ulceration. Histopathologically, the tumor is characterized by the proliferation of basaloid cells in solid, cribriform, and tubular patterns. The diagnosis of this lesion is often challenging due to its deceptively benign clinical course and often carries a poor prognosis due to its high recurrence rate.[3] We report a case of AdCC in the lower lip and buccal mucosa of a patient clinically mimicking mucocele with a literature review emphasizing their diagnosis and prognosis.

  Case Report Top

A 48-year-old male patient came to the Department of Oral Medicine with a chief complaint of swelling on the left side of the lower lip and cheek for the past 5 months. On eliciting history, the patient revealed that the swelling was initially small in size and in due course of time grew to the present size. Surgical history revealed that the patient had a similar swelling in the left cheek 6 months back which was surgically excised and diagnosed histopathologically as pleomorphic adenoma.

On intraoral examination, a single diffuse swelling was evident in the labial mucosa, measuring approximately 1.5 cm × 2 cm in dimension, extending from the midline of the lower lip to 1 cm in front of the left commissure of the lip mediolaterally [Figure 1]. The left buccal mucosa elicited a single diffuse swelling measuring approximately 1.9 cm × 2.5 cm extending anterio-posteriorly from the commissure of the lip to 46 regions along the occlusal plane [Figure 2]. The mucosa over both the swellings appeared normal with no evidence of secondary changes. On palpation, both the swellings were nontender and soft to firm in consistency.
Figure 1: Intra oral picture depicting the tumor on the lower lip

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Figure 2: Surgical removal of the tumor on the buccal mucosa

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Based on the history and clinical features, the swelling on the buccal mucosa was provisionally diagnosed with recurrent pleomorphic adenoma and the swelling on the lower lip was provisionally diagnosed with mucocele. The lesions were surgically excised under local anesthesia and submitted for histopathological examination [Figure 3].
Figure 3: Specimen submitted for histopathological examination

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Microscopic examination of both lesions revealed a similar histopathological picture. Sections showed solid sheets and nests of basaloid tumor cells arranged in a cribriform pattern and separated by collagenous stroma [Figure 4]. The islands of basaloid cells were interspersed with cyst-like spaces filled with basophilic mucoid material [Figure 5] and [Figure 6]. The tumor cells were also seen infiltrating into the deeper muscular tissues. Based on the microscopic findings, a final diagnosis of AdCC – Cribriform type was made. The patient was under our follow-up for 1 year during which there were no complications or signs of recurrence.
Figure 4: Histopathology ×10 depicting islands of tumor cells separated by collagenous stroma

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Figure 5: Histopathology ×20 depicting cribriform architecture showing characteristic Swiss cheese pattern

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Figure 6: Histopathology ×40 depicting pseudocystic spaces filled with basophilic mucoid material

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  Discussion Top

AdCC, is a malignant salivary gland neoplasm that was first reported in 1853. Theodor Billroth in 1859 coined the term “cylindroma” because of its characteristic histopathological appearance, the terminology was however later dropped because of its erroneous perception of a benign entity.[4] It was only later in 1953, that Foote and Frazel coined the term “adenoid cystic carcinoma” which is the currently accepted terminology followed by the World Health Organization.[5]

The exact etiology for the development of this tumor is unknown, but most of these tumors carry translocation of genes on chromosome t(6:9)(q22-23; p23-24) leading to the production of the fusion gene MYB-NFIB which is believed to drive the proliferation of the tumor cells in AdCC by regulating genes involved in various biological processes like cell cycle, DNA replication, and RNA processing.[6] The histogenesis and morphogenesis of the tumor have been attributed to the proliferation of both the ductal and myoepithelial cells with varying degrees of extracellular matrix production.[7]

AdCC mostly frequents the intraoral minor salivary glands, especially the palate followed by the tongue, but cases have been reported in the major salivary glands also. Cases have been reported in numerous extraoral sites such as lacrimal glands, breast, vulva, nasal cavity, ceruminal glands, and skin as well. In the current case, the lesion was noted on the lower lip and buccal mucosa which is extremely rare and worth highlighting.

The peak incidence is usually between the 5th and 6th decades of life with a predominant female predilection.[8],[9] Tumors of the minor salivary gland generally present as a painless swelling that often mimics benign tumors because of their indolent growth, which poses a diagnostic challenge to the clinician.[10] In the present case, the history and complete asymptomatic nature of the lesion made us incline toward a diagnosis of recurrent pleomorphic adenoma and mucocele. However, histopathology proved otherwise.

Histopathologically, AdCC is characterized by the proliferation of ductal and myoepithelial cells in various morphological patterns, notably cribriform, tubular and solid, with cribriform being the most common. The cribriform pattern is characterized by the presence of islands of basaloid cells that contain multiple cylindrical psuedocystic spaces often filled with basophilic Periodic acid–Schiff positive, mucoid material giving the characteristic “swiss cheese appearance.” The tubular pattern is composed of duct-like structures lined by cuboidal cells and surrounded by basaloid cells. The solid pattern is characterized by large islands and sheets of tumor cells exhibiting a central area of necrosis commonly termed as “comedo necrosis.” This pattern often shows varying degrees of cellular pleomorphism and mitosis, which is often sparse in other patterns.[11] AdCC also has a propensity to invade nerves and hence can be locally destructive, although distant metastasis is usually rare.

The diagnosis of AdCC is largely based on histopathological examination. The identification of fusion gene MYB-NFIB through in situ hybridization techniques has also proven successful in diagnosing this entity. One of the major differential diagnoses for AdCC is polymorphous adenocarcinoma because of its similar morphological architecture and proclivity for perineural invasion. Immunohistochemistry can aid in such cases, as AdCC is generally positive for SMA, p40, c-kit, while polymorphous adenocarcinoma is usually negative. The Ki-67 index is also higher (>10%) in AdCC when compared to polymorphous adenocarcinoma.[12],[13]

The treatment of AdCC involves wide local surgical excision with or without concomitant radiation therapy depending on the site of the lesion. Due to the anatomy of the head-and-neck region and the neurotrophism of the tumor, radiation therapy is often used as an adjunct following surgery.[14] The long-term prognosis of AdCC is generally poor. Factors that predict poor prognosis include tumor size, solid architecture, lymphovascular invasion, and perineural invasion.[3],[8],[15] Patients have to be followed up for long periods as this tumor is prone to loco-regional recurrence and eventual distant metastasis. Cases have also been reported to undergo dedifferentiation into high-grade carcinomatous and sarcomatous components.[16],[17]

  Conclusion Top

AdCCs of the lower lip and buccal mucosa are extremely uncommon and hence is often not included in the differential diagnosis of tumors in these areas. AdCC poses a diagnostic challenge even to experienced clinicians due to its indolent growth, often deceptively imitating benign salivary gland tumors as was seen in our case where the lesion on the lip clinically mimicked a mucocele while the lesion on the buccal mucosa gave us the impression of recurrent pleomorphic adenoma. This entity must however be considered as a differential diagnosis for all minor salivary gland tumors and treated at the earliest. Early detection of these tumors is often the key to a favorable prognosis and disease-free survival of the patients. This case report highlights the possibility of AdCCs occurring in uncommon sites within the oral cavity and often mimicking other benign entities.

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

Ciccolallo L, Licitra L, Cantú G, Gatta G, EUROCARE Working Group. Survival from salivary glands adenoid cystic carcinoma in European populations. Oral Oncol 2009;45:669-74.  Back to cited text no. 1
de Almeida-Pinto YD, Costa SFDS, de Andrade BAB, Altemani A, Vargas PA, Abreu LG, et al. t(6;9)(MYB-NFIB) in head and neck adenoid cystic carcinoma: A systematic review with meta-analysis. Oral Dis 2019;25:1277-82.  Back to cited text no. 2
Cao C, Ge M, Chen X, Xu J, Chen C. Clinical outcomes and prognostic factors of salivary gland adenoid cystic carcinomas: A case control study. Oral Surg Oral Med Oral Pathol Oral Radiol 2017;123:531-5.  Back to cited text no. 3
Ellis GL, Auclair PL, Gnepp DR, editors. Surgical Pathology of the Salivary Glands. Washington D.C: Saunders; 1991. p. 580.  Back to cited text no. 4
Foote FW, Frazell EL. Tumors of the major salivary glands. Cancer 1953;6:1065-133.  Back to cited text no. 5
Wysocki PT, Izumchenko E, Meir J, Ha PK, Sidransky D, Brait M. Adenoid cystic carcinoma: Emerging role of translocations and gene fusions. Oncotarget 2016;7:66239-54.  Back to cited text no. 6
Dwivedi N, Agarwal A, Raj V, Chandra S. Histogenesis of salivary gland neoplasms. Indian J Cancer 2013;50:361-6.  Back to cited text no. 7
[PUBMED]  [Full text]  
Atallah S, Casiraghi O, Fakhry N, Wassef M, Uro-Coste E, Espitalier F, et al. A prospective multicentre REFCOR study of 470 cases of head and neck adenoid cystic carcinoma: Epidemiology and prognostic factors. Eur J Cancer 2020;130:241-9.  Back to cited text no. 8
Mu X, Li Y, He L, Guan H, Wang J, Wei Z, et al. Prognostic nomogram for adenoid cystic carcinoma in different anatomic sites. Head & Neck. 2021;43:48-59.  Back to cited text no. 9
Oliveira GA, de Farias AC, Mosconi C, Fonseca FP, da Silva TA, de Mendonça EF, et al. Adenoid cystic carcinoma of salivary glands: Clinicopathologic analysis of 44 cases. Oral Surg Oral Med Oral Pathol Oral Radiol 2020;129:e137.  Back to cited text no. 10
Batsakis JG, Luna MA, el-Naggar A. Histopathologic grading of salivary gland neoplasms: III. Adenoid cystic carcinomas. Ann Otol Rhinol Laryngol 1990;99:1007-9.  Back to cited text no. 11
Rooper L, Sharma R, Bishop JA. Polymorphous low grade adenocarcinoma has a consistent p63+/p40- immunophenotype that helps distinguish it from adenoid cystic carcinoma and cellular pleomorphic adenoma. Head Neck Pathol 2015;9:79-84.  Back to cited text no. 12
Darling MR, Schneider JW, Phillips VM. Polymorphous low-grade adenocarcinoma and adenoid cystic carcinoma: A review and comparison of immunohistochemical markers. Oral Oncol 2002;38:641-5.  Back to cited text no. 13
Chen Y, Zheng ZQ, Chen FP, Yan JY, Huang XD, Li F, et al. Role of postoperative radiotherapy in nonmetastatic head and neck adenoid cystic carcinoma. J Natl Compr Canc Netw 2020;18:1476-84.  Back to cited text no. 14
Martins-Andrade B, dos Santos Costa SF, Sant'ana MSP, Altemani A, Vargas PA, Fregnani ER, et al. Prognostic importance of the lymphovascular invasion in head and neck adenoid cystic carcinoma: A systematic review and meta-analysis. Oral Oncol 2019;93:52-8.  Back to cited text no. 15
Dutta A, Arun P, Arun I. Adenoid cystic carcinoma with transformation to high grade carcinomatous and sarcomatoid components: A rare case report with review of literature. Head Neck Pathol 2020;14:1094-104.  Back to cited text no. 16
Chia N, Petersson F. Adenoid cystic carcinoma with dedifferentiation/expansion of the luminal cell component and preserved biphasic morphology - Early high-grade transformation. Ann Diagn Pathol 2020;50:151650.  Back to cited text no. 17


  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]


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