BACKGROUND: Basal cell adenoma (BCA) is a rare benign tumor within the salivary glands. Basal cell adenocarcinoma (BCAC), the malignant counterpart of BCA, is also an exceedingly rare tumor with very limited clinical studies conducted. This study aims to investigate the clinical characteristics, demographics, and surgical outcomes of patients diagnosed with BCA and BCAC within the parotid gland.
METHODS: A retrospective analysis from May 2003 to August 2023 was performed for all patients undergoing parotidectomy for masses. Retrospective data on gender, age, tumor characteristics, and outcomes were collected. Surgical approaches, including negative margin attainment, capsule removal, and histological diagnosis, were also detailed.
RESULTS: The study included 1268 patients who underwent parotidectomy, resulting in 81 cases of BCA and 7 cases of BCAC. BCA patients, with a mean age of 55.1 years, showed diverse age distribution and predominantly presented in the 50s. In BCAC cases, seven female patients exhibited a predominant location in the deep lobes. FNA revealed BCAC in three out of seven cases, and subsequent parotidectomy was performed, resulting in no observed recurrences or metastases.
CONCLUSIONS: This study reports the largest number of BCA cases from a single institution and provides comprehensive insights into the demographics, tumor characteristics, and clinical outcomes of both BCA and BCAC. Although further research should be conducted, based on clinical follow-up results, appropriately including the capsule in the tumor excision indicates favorable outcomes, especially when the tumor size is not large.

Basal cell adenoma (BCA) is a rare, benign tumor originating from the epithelial cells of the salivary glands. It was earlier categorized as a subtype of monomorphic adenoma with distinctive histopathological features. BCA usually manifests as asymptomatic, slow-growing masses that exhibit a site and age predilection, commonly affecting the major salivary glands of elderly female patients. Histologically, solid, trabecular, tubular, and membranous patterns are recognized. It is imperative to establish a precise distinction between BCA, pleomorphic adenoma, and malignant salivary gland tumors before initiating treatment to ensure effective management. The standard treatment approach is surgical resection of the tumor. Recurrence and malignant transformation rarely occur, except for the membranous subtype. This article aims to report an unusual case of BCA arising from a minor salivary gland in the upper lip. The post-operative course was unremarkable, with complete healing of the surgical site. No recurrence was observed during a one-year follow-up. BCA arising from a minor salivary gland in the upper lip is an extremely uncommon entity. A comprehensive review of BCA in the upper lip, reported from 1991 to December 2023, revealed only 14 cases.

OBJECTIVE: TRPS1 is a new, sensitive marker for breast carcinoma (BC). Salivary glands and breasts are both exocrine glands; thus, their tumors may share similar morphology and immunophenotype. Among salivary gland-type BC, TRPS1 is reported to be positive in secretory carcinomas (SCs) but negative in acinic cell carcinomas (AciCCs) and most adenoid cystic carcinomas (AdCCs). A subset of salivary duct carcinomas (SDCs) is positive for TRPS1. Herein, we investigate TRPS1 immunohistochemical expression in salivary gland tumors (SGTs).
METHODS: A retrospective search yielded 110 SGTs (97 primary and 13 metastatic). TRPS1 immunohistochemistry was scored as negative, low positive, intermediate positive, or strongly positive.
RESULTS: TRPS1 was expressed in 78% (14/18) of pleomorphic adenoma (PA) cases but negative/low positive in all Warthin tumors (6/6 [100%]). In basal cell adenoma (BCA), TRPS1 expression was intermediate to strong (13/14 [92%]) in the stromal cells, whereas ductal or basal cells showed low expression. TRPS1 expression varied in malignant SGTs, with intermediate to strong staining in 100% (15/15) of AdCCs, 100% (5/5) of basal cell adenocarcinoma, 100% (3/3) of intraductal carcinoma, 89% (8/9) of polymorphous adenocarcinoma, and 89% (7/8) of SDCs; negative/low positive expression was observed in 100% (3/3) of SCs, 89% (8/9) of AciCCs, and 50% (3/3) of mucoepidermoid carcinomas. In addition, strong and intermediate TRPS1 expression was observed in metastatic SGT to the lungs, lymph nodes, and soft tissue.
CONCLUSIONS: Overall, TRPS1 is strongly expressed in PA as well as malignant and metastatic SGT. In addition, TRPS1 is positive in stromal cells of BCA but negative or low positive in ductal and basal cells.

Infarction has rarely been reported in some types of salivary gland tumors. In this study, we present the first case of infarction occurring in salivary basal cell adenoma. A 62-year-old male presented with swelling in the left parotid region. Histopathological examination revealed extensive central necrosis surrounded by a rim of viable tumor tissue showing the typical histology of basal cell adenoma. Nuclear β-catenin expression and the CTNNB1 p.I35T (c.104 T > C) mutation were identified in the tumor. A diagnosis of basal cell adenoma with central necrosis was made, and the postoperative period was uneventful. In addition, we review the literature on CTNNB1 I35T mutations in basal cell neoplasms of the salivary glands. Awareness of the possible occurrence of infarction and the high frequency of the unique mutation in basal cell adenoma may help in the differential diagnosis of salivary gland tumors.

Basal cell adenoma is a rare benign neoplastic lesion of the parotid gland, therefore it is rarely diagnosed in preoperative work-up by fine needle aspiration cytology. This distinctive entity being regarded as one of the scarce salivary neoplasms is predominantly perceived in the female population, but is uncommon in young adults. It is extremely challenging to diagnose basaloid tumors predominantly basal cell adenoma of the salivary gland on cytopathology. Therefore present case report describes the fine needle aspiration cytology diagnosis of basal cell adenoma in the left parotid gland in a 40-year-old female. The case report also describes the cytomorphological characters, the cytological differential diagnoses and immunohistochemistry of basal cell adenoma.

Neoplasms of the salivary glands are of rare incidence, have a vague presentation, and follow a complex long-term clinical course. Both minor and major salivary glands have been implicated in dysplastic transformation, with parotid gland tumors being the most notable. Most of these tumors are benign in nature and are typically diagnosed and classified based on their histopathological presentation. In this report, we exhibit a rare case of basal cell adenomas (BCA), localized to the right parotid gland, in a 69-year-old male patient. Volume acquisition computed tomography (CT) imaging of the region was obtained with and without contrast, with relative reconstruction in both the coronal and axial planes. A soft tissue mass of 5 cm in diameter was detected in the superficial lobe of the right parotid gland. Fine needle aspiration (FNA) with ultrasound guidance revealed a population of basaloid cells that is monomorphic with minimal nuclear atypia and scattered fibrillary matrix. Thereafter, the patient was treated with partial excision of the right parotid gland under general anesthesia, and the post-operative pathology report confirmed the diagnosis of basal cell adenoma. The patient was doing well post-operatively with no complaints and maintained routine clinic follow-ups.

One of the rare tumors of the salivary gland is known as basal cell adenoma (BCA). Only a small percentage of salivary gland tumors affect the minor salivary gland of the oral cavity while the majority are found in the parotid gland. We present a rare case of BCA involving the left buccal mucosa of a 45-year-old female. Magnetic resonance imaging (MRI) showed well defined solid mass measuring 1.9 x 1.5 cm in the left buccal space inseparable from the buccinator muscle. The T2-weighted image demonstrates a hyperintense signal post-contrast. Ultrasound-guided fine needle aspiration cytology revealed cellular basaloid neoplasm of uncertain malignant potential. Thereafter excision of the mass was performed through a transoral approach under general anesthesia. Histopathology of the mass showed encapsulated basal cell neoplasm in favor of BCA. The patient was doing well after the surgery and has intact facial nerve and adjacent nerves such as the auriculotemporal nerve and great auricular nerve with no complications then she kept on routine clinic follow-ups, and the surgical site recovered successfully. Therefore, we conclude that MRI and biopsy provide useful information to differentiate between benign adenoma and malignant adenocarcinoma. BCA should be considered in a differential diagnosis of an isolated neck mass. Surgical excision demonstrates an excellent prognosis.

A 65-year-old female patient with a history of wearing a denture for 15 years reported with a complaint of pain in the floor of the mouth. On examination, a swelling measuring about 2.2 X1.2 cms was noted in the floor of the mouth on the left side. The lesion was excised under local anesthesia. Histopathology revealed a cystic lesion with basaloid cells arranged in tubules, nests and cribriform pattern. A diagnosis of basal cell adenoma was made and confirmed by immunohistochemistry. We report a rare case of Basal Cell Adenoma of the floor of the mouth which mimicked a ranula. The predominantly cystic nature of this basaloid tumor posed a diagnostic challenge. Histopathological and immunohistochemical analysis to arrive at a definitive diagnosis aid in treatment planning and prognostication.

Basal cell adenomas (BCA) arising from the nasal cavity or paranasal sinuses are very rare. A 64-year-old male patient was suspected of having a malignant tumor after undergoing preoperative computed tomography scans and magnetic resonance imaging. The intraoperative frozen section showed a malignant tumor; however, the final diagnosis revealed BCA with atypia, tubular pattern.

Adenoid cystic carcinoma (ACC) is one of the most common primary salivary gland cancers. ACC has several benign and malignant mimics amongst salivary gland neoplasms. An accurate diagnosis of ACC is essential for optimal management of the patients and their follow-up. Upregulation of MYB has been described in 85-90% of ACC, but not in other salivary gland neoplasms. In ACC, MYB upregulation can occur as a result of a genetic rearrangement t(6;9) (q22-23;p23-24), MYB copy number variation (CNV), or enhancer hijacking of MYB. All mechanisms of MYB upregulation result in increased RNA transcription that can be detected using RNA in situ hybridisation (ISH) methods. In this study, utilising 138 primary salivary gland neoplasms including 78 ACC, we evaluate the diagnostic utility of MYB RNA ISH for distinguishing ACC from other primary salivary gland neoplasms with a prominent cribriform architecture including pleomorphic adenoma, basal cell adenoma, basal cell adenocarcinoma, epithelial myoepithelial carcinoma, and polymorphous adenocarcinoma. Fluorescent in situ hybridisation and next generation sequencing were also performed to evaluate the sensitivity and specificity of RNA ISH for detecting increased MYB RNA when MYB gene alterations were present. Detection of MYB RNA has 92.3% sensitivity and 98.2% specificity for a diagnosis of ACC amongst salivary gland neoplasms. The sensitivity of MYB RNA detection by ISH (92.3%) is significantly higher than that of the FISH MYB break-apart probe (42%) for ACC. Next generation sequencing did not demonstrate MYB alterations in cases that lacked MYB RNA overexpression indicating high sensitivity of MYB RNA ISH for detecting MYB gene alterations. The possibility that the sensitivity may be higher in clinical practice with contemporary samples as compared with older retrospective tissue samples with RNA degradation is not entirely excluded. In addition to the high sensitivity and specificity, MYB RNA testing can be performed using standard IHC platforms and protocols and evaluated using brightfield microscopy making it a time and cost-efficient diagnostic tool in routine clinical practice.