|Year : 2022 | Volume
| Issue : 3 | Page : 765-769
Basal cell adenocarcinoma of the minor salivary gland - A rare case report involving the upper lip
A Jacob Prakash1, S Sushmitha Christina1, M Vijaya Lakshmi1, Naveen Polishetty2
1 Department of Oral and Maxillofacial Pathology, Lenora Institute of Dental Sciences, Rajahmundry, Andhra Pradesh, India
2 Department of Oral and Maxillofacial Surgery, Konaseema Institute of Dental Sciences, Amalapuram, Andhra Pradesh, India
|Date of Submission||25-Jan-2020|
|Date of Decision||06-Apr-2020|
|Date of Acceptance||22-Jun-2020|
|Date of Web Publication||25-Jul-2022|
M Vijaya Lakshmi
Department of Oral and Maxillofacial Pathology, Lenora Institute of Dental Sciences, Rajahmundry, Andhra Pradesh
Source of Support: None, Conflict of Interest: None
Minor salivary gland neoplasms constitute up to approximately 25% of all salivary gland tumors. The incidence of malignancy of these tumors is slightly greater than half. Basal cell adenocarcinoma (BCAC) is a rare salivary gland malignancy that occurs most commonly in the parotid gland. In this report, we describe a case of an older woman presenting with BCAC of the upper lip arising from the minor salivary gland.
Keywords: Basal cell adenocarcinoma, minor salivary gland neoplasm, upper lip lesion
|How to cite this article:|
Prakash A J, Christina S S, Lakshmi M V, Polishetty N. Basal cell adenocarcinoma of the minor salivary gland - A rare case report involving the upper lip. J Can Res Ther 2022;18:765-9
|How to cite this URL:|
Prakash A J, Christina S S, Lakshmi M V, Polishetty N. Basal cell adenocarcinoma of the minor salivary gland - A rare case report involving the upper lip. J Can Res Ther [serial online] 2022 [cited 2022 Aug 10];18:765-9. Available from: https://www.cancerjournal.net/text.asp?2022/18/3/765/348224
| > Introduction|| |
Basal cell adenocarcinoma (BCAC) is a rare salivary gland tumor, which is considered to be the malignant counterpart of basal cell adenoma (BCA). BCAC accounts for only 2.9% of all malignant salivary neoplasms, which was included in the 1991 World Health Organization (WHO) classification. In 2005, the WHO classification simply defined BCAC as being an infiltrative epithelial neoplasm. It affects predominantly the major salivary glands, and there are very few reports of them occurring in the minor salivary glands. BCAC may arise either de novo or from a preexisting BCA with which it shares demographic and histologic features. We report an interestingly rare case of BCAC affecting the upper labial mucosa in a 70-year-old female.
| > Case Report|| |
A 70-year-old female patient presented with a chief complaint of slow-growing painless swelling on the upper labial mucosa for the past 18 months that was sudden in onset and was smaller initially and gradually attained the present size. On clinical examination, extraorally, a solitary diffuse swelling was seen on the right corner of the upper lip measuring approximately about 2 cm × 1.7 cm in size extending superioinferiorly from the right nasolabial fold to the lower border of the upper lip and mediolaterally from 1 mm away from philtrum to the right corner of the upper lip [Figure 1]. The skin over the swelling is normal. Intraoral examination revealed a lobulated mass measuring 2.5 cm × 2 cm × 1 cm in diameter, with well-defined borders extending superioinferiorly from the upper right labial vestibule to the vermillion border of the upper lip and mesiodistally from the distal aspect of 11 to the mesial aspect of 14 region with no surface ulceration [Figure 2]. Upon palpation, the swelling was firm, nontender, noncompressible, nonpulsatile. Regional lymph nodes were not palpable. Based on clinical features, the lesion was diagnosed as neurofibroma. Complete surgical excision was done [Figure 3], and the specimen was sent to the department of oral and maxillofacial pathology for a definitive diagnosis.
|Figure 1: A diffuse solitary swelling is seen on the right corner of the upper lip|
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|Figure 2: Clinical appearance of a lobulated mass on the upper labial mucosa|
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On gross pathologic examination, it was a firm, unencapsulated, creamish brown oval mass with irregular surface and borders which was grossed into three bits [Figure 4] and was subjected to histochemical processing.
Microscopic examination with hematoxylin and eosin staining showed an unencapsulated salivary gland neoplasm consisting of infiltrative basaloid cells containing basophilic granular cytoplasm with hyperchromatic nuclei and cuboidal ductal cells. The neoplasm predominantly showed membranous growth pattern [Figure 5] with abundant hyalinized collagenous stroma surrounding the individual tumor islands [Figure 6] and with few areas arranged in tubulo-trabecular growth pattern, which was intermixed with the areas of necrosis. The neoplastic clusters comprised two-cell population with peripherally arranged hyperchromatic low cuboidal cells, showing palisading arrangement and central larger pale staining cells [Figure 7]. Tumor cells showed cellular and nuclear pleomorphism with few abnormal mitotic figures. Tumor islands were infiltrating the adjacent skeletal muscle [Figure 8] and perineural invasion was evident [Figure 9]. Based on these findings, a histopathological diagnosis of BCAC of membranous type was made.
|Figure 6: Individual tumor islands surrounded by hyalinized collagenous stroma (×40)|
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|Figure 7: Tumor islands showing a dual population of low columnar peripheral palisading hyperchromatic cells with central polygonal pale staining cells (×40)|
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|Figure 8: Infiltrative tumor islands into adjacent skeletal muscle (×40)|
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| > Discussion|| |
BCAC, previously known as basaloid salivary carcinoma, carcinoma ex monomorphic adenoma, and malignant BCA, accounts for 1.6% of all salivary neoplasms and 2.9% of all malignant salivary neoplasms., It appears to have been first described between 1974 and 1978, but it was not referred to as BCAC until 1988. First recognized as a salivary gland neoplasm by the WHO in 1991, BCAC was more specifically defined in 2005 as an epithelial neoplasm that has cytological characteristics of BCA, but a morphologic growth pattern indicative of malignancy. BCAC is a low-grade malignant neoplasm with a cytologic resemblance to BCA, but demonstrating invasive growth pattern, and sometimes demonstrates perineural or vascular invasion.
The overwhelming majority arise in the parotid (90%) and submandibular glands with very few reported in the minor salivary glands.
Luna et al. reported the first minor salivary gland BCAC, located in the palate. Minor salivary gland BCAC continues to be an extremely rare entity. The recent literature review lists a total of 72 cases of minor salivary gland BCAC documented, and the present case report adds to it.
Overall, minor salivary gland tumors typically are located on the hard palate; however, in the few available cases of minor salivary gland BCAC, they arise commonly from the buccal mucosa, in addition to the palate, followed by lip and tongue.
This tumor predominates at the seventh decade being more common in females as seen in the present case and is believed to arise from the pluripotent ductal reserve cells.,
Like most salivary gland tumors, swelling which is slow growing is the principal symptom, but pain or tenderness occasionally may be an associated complaint. Occasionally, the swelling has been described as rapid in onset, but it does not have any prognostic significance.
This tumor has four major histologic growth patterns: solid, trabecular, tubular, and membranous. A solid pattern – most common type of BCAC in which variable sized and shaped cell nests are separated by thin septa or thick bands of collagenous stroma. This pattern is predominant in about two-thirds of the tumors. In the membranous type, tumors produce excessive amounts of eosinophilic, hyalinized basal lamina material that forms intercellular droplets and surrounds individual tumor islands. Interconnecting cords and bands of the basaloid cells characterize the trabecular growth pattern. In the tubular type, there are luminal spaces among the basaloid cells.,,
BCAC is composed of two cell types – small cells with darkly staining nuclei and a high nuclear-to-cytoplasm ratio, and larger central polygonal cells with pale basophilic nuclei and eosinophilic-to-amphophilic cytoplasm – and sometimes may form squamous eddies within islands of the tumor. The cells are usually arranged in nests of varying size embedded in the collagenous stroma with a palisading pattern of smaller cells at the periphery of the nests. In both types of cells, the cell-to-cell boundaries are indistinct. Cytologic indices of malignancy are generally low. Tumor cell necrosis is notable in only small number of tumors. However, it exhibits invasive growth pattern. Nests and strands of the tumor cells insinuate into salivary gland lobules and into adjacent structures such as skeletal muscle and fat. About one-third tumors have displayed perineural invasion, and one-fourth have exhibited intravascular invasion.,
It is important to differentiate BCAC from other basaloid cell tumors of the minor salivary glands because of the prognostic and potential differences in treatment, particularly BCA, adenoid cystic carcinoma (ACC), basaloid squamous cell carcinoma (BSCC), and undifferentiated carcinoma.
ACC is similar to BCAC in that perineural and intravascular invasion are common to both as both are hyaline nodules within their basement membranes. However, ACC is ruled out in the present case due to the dual population of large pale cells and small dark cells of BCAC unlike ACC is composed of pale cells with irregularly angulated nuclei and with high mitotic rate and increased frequency of necrosis, which favors the diagnosis of ACC over BCAC. In addition, ACC is commonly associated with a cribriform pattern and pseudocysts filled with basophilic mucin and eosinophilic PAS-positive hyaline, which are not found in the present case. Differentiating between BCAC and ACC is of particular importance due to the differences in prognosis. The 10-year survival rate for BCAC is above 75%, whereas the 10-year survival rate for ACC is around 30%, owing to its tendency for hematogenous spread, especially to the lungs.
BSCC may also be mistaken for BCAC because of the similar characteristics in the basaloid morphology, hyaline deposits, and peripheral palisading. However, BSCC can be differentiated by histopathological findings of central necrosis, high tumor grade, and squamous differentiation, which were not found in our present case. Furthermore, BSCC is commonly found in the hypopharynx, base of the tongue, and supraglottic larynx, locations where BCAC is rarely encountered. The distinction between BSCC and BCAC is further aided by immunohistochemical findings: BSCC stains negatively for Ber-EP4, vimentin, and S-100 protein, whereas BCAC may stain positively for these three markers., Canalicular adenoma frequently occurs in the minor salivary glands of the upper lip, and its multifocal origin may be mistaken for malignant invasion. It can be differentiated from similar malignant neoplasms by its uniform beaded double strands of the columnar epithelium, cyst formation, loose vascular stroma, and lack of destruction or invasion.,
Distinguishing BCAC from BCA may be the most difficult of these distinctions, owing to their histopathological similarities. Often, BCAC shows considerable cytologic atypia and an increased mitotic rate compared with BCA (a proliferative index >10%, as measured by Ki-67 [mib-1] immunostaining, raises suspicion for malignancy). However, these differences alone are not sufficiently reliable to render a definitive diagnosis. The hallmark characteristics of malignancy are gross or microscopic invasion into the surrounding soft tissue and perineural or vascular invasion. In addition, BCA tends to be encapsulated, whereas BCAC typically is not. Some BCAs have features that imitate BCAC such as multinodularity, pushing growth pattern, or multifocal origin. The pathologist must take extra precaution in such cases to carefully distinguish both the entities.
The widely accepted treatment for BCAC is complete surgical excision. With major salivary glands, either superficial or whole-gland excision is recommended, depending on the gland and the depth of tumor invasion. Minor salivary gland tumors have a tendency for infiltration of adjacent soft tissues and therefore require wide local excision to ensure complete resection. Frozen section microscopic examination of the surgical margins should be performed to ensure complete excision of both major and minor salivary gland tumors.,,, These are considered as low-grade adenocarcinomas with a relatively good prognosis. Regional lymph node dissection is recommended only if there is evidence of metastatic disease to the cervical chain, and adjuvant radiation therapy has been used for invasive tumors and local recurrences.
| > Conclusion|| |
BCAC is a rare salivary gland tumor that carries a favorable prognosis. Our aim in presenting this case report is to increase awareness of minor salivary gland BCAC arising in the upper lip and better characterize of the disease. Although there are few reported cases of BCAC of minor salivary gland origin, BCAC should remain a diagnostic consideration. It is a low-grade, infiltrative, locally destructive malignant neoplasm with a predilection for local recurrence that rarely metastasizes. It is treated with complete surgical excision and possible adjuvant radiation therapy. Since these tumors typically require only local excision, they must be distinguished histologically from ACC, which has a poorer prognosis and often necessitates a more aggressive clinical approach.
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 her consent for her images and other clinical information to be reported in the journal. The patient understands that her name and initials will not be published and due efforts will be made to conceal her identity, but anonymity cannot be guaranteed.
I thank all the authors for their valuable contribution regarding this case report.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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