Canalicular adenoma: a clinicopathologic and immunohistochemical analysis of 67 cases with a review of the literature

The basaloid-spectrum of salivary gland tumors: A focused review with practical diagnostic considerations

Basaloid salivary gland neoplasms are a diverse and varied group of benign and malignant tumors. The term 'basaloid' is broadly used in reference to cells with elevated nuclear to cytoplasmic ratio, sparse cytoplasm, and hyperchromatic nuclei. However, a subset may also fit within the "small round blue cell tumor" morphologic category or the "biphasic" salivary gland tumor category. Furthermore, there are no established thresholds for the proportion of basaloid tumor cells needed to consider a tumor within the basaloid spectrum. Given the implicit variability in what is considered a basaloid salivary gland tumor, one may question the inclusion of certain entities (canalicular adenoma, HMGA2::WIF1 pleomorphic adenoma, polymorphous adenocarcinoma) in this review based on classic morphologic features. However, salivary gland tumors with even minor basaloid components may appear 'basaloid' in small biopsy specimens and, thus, a choice was made to focus on common and uncommon diagnostic differentials with this in mind. Entities that will be covered in this review also include basal cell adenoma and basal cell adenocarcinoma, adenoid cystic carcinoma, lymphoepithelial carcinoma, sialoblastoma, adamantinoma-like Ewing Sarcoma, NUT carcinoma, and carcinoma showing thymus-like differentiation.

Canalicular Adenoma in the Parotid Gland: A Rare Case Study

Canalicular adenoma (CA) is a rare benign tumor of the salivary glands, predominantly affecting elderly females, with a strong predilection for the upper lip. While CA commonly arises in the minor salivary glands, its occurrence in the parotid gland is exceptionally rare. In this report, we present a unique case of CA in the parotid gland, adding to the scant literature with only 8 documented instances. The patient, a 57-year-old Asian male, presented with a painless swelling in the left parotid gland that had been persisting for 8 years. Clinical examination and imaging studies identified a lobulated mass, prompting surgical intervention. The patient underwent a superficial parotidectomy, and pathological examination of the excised tissue confirmed the diagnosis of CA, with no signs of malignancy. This case illustrates the diagnostic and management challenges associated with CA, particularly given its rare presentation in the parotid gland. Accurate diagnosis is reliant on surgical biopsy, and careful surgical planning is imperative, especially considering the proximity of the facial nerve. Our case underscores the need for heightened awareness of CA's unique presentations, particularly within the Asian population. Given the potential for recurrence, long-term follow-up is essential. Further research is needed to elucidate the biological behavior of CA and to refine management strategies for optimal patient outcomes.

Canalicular-Like Pleomorphic Adenoma of the Parotid Gland: A Recently Classified Tumor Highlighting the Use of Frozen Section Analysis and Surrogate IHC for Gene Rearrangement Defined Subtypes

Canalicular-like pleomorphic adenomas are a relatively recently described entity, that possess features of both canalicular adenomas and pleomorphic adenomas. The presence of unusual HMGA2-fusion partners (most commonly HMGA2::WIF1 gene fusions) has established canalicular-like pleomorphic adenoma as a distinct entity. The use of intraoperative frozen section analysis and surrogate HMGA2 IHC are 2 tools that can provide the surgical team with valuable insight into intraoperative decision making and final classification of rare tumors of the parotid gland, respectively. We present a case of canalicular-like pleomorphic adenoma and characterize its appearance on frozen section analysis. HMGA2 IHC staining was retroactively performed, assisting in the confirmation of the tumor subtype.

Clinicopathological characteristics of pleomorphic adenoma from the labial gland: A 20-year experience with 173 cases in one single institution

OBJECTIVE

Pleomorphic adenoma (PA) of the lip is not a common phenomenon, and existing literature provides limited information on the clinicopathological features of labial PA.

STUDY DESIGN

Patients diagnosed with labial PA at our single institution over the past 20 years (2001-2020) was retrospectively screened and analyzed to investigate the epidemiologic and clinicopathological features of these tumors.

RESULTS

A total of 173 cases were screened out, and the average age was 44.3 (range 7-82) years, with a peak incidence rate during the third decade. A slight predilection for men (52%) was observed, and PA occurs more frequently in the upper lip than in the lower lip, with a ratio of 14.7:1. On clinical examination, labial PAs usually present as painless masses that develop slowly with no systemic symptoms. Histologically, labial PAs contain myoepithelial and polygonal epithelial cells in myxoid, hyaline, fibrous, chondroid, and even osseous tissues, similar to those in other sites. Specifically, 15 of 173 patients with labial PA presented with cutaneous PA.

CONCLUSION

Labial PA presents over a wide age range and dominantly occurs at the upper lip. Surgical resection is the major treatment strategy, and postoperative recurrence or malignant transformation of labial PA was extremely rare.

Salivary gland pathologies: evolution in classification and association with unique genetic alterations

PURPOSE

The correct classification of salivary gland pathologies is crucial for choosing a treatment method and determining the prognosis. Better outcomes are now achievable thanks to the introduction of new therapy approaches, such as targeted therapies for malignant salivary gland tumors. To apply these in clinical routine, a clear classification of the lesions is required.

METHODS

The following review examines all changes from the first World Health Organization (WHO) Classification of salivary gland pathologies from 1972 to fifth edition from 2022. Possible developments in the diagnosis and classification of salivary gland pathology are also presented.

RESULTS

The current WHO classification is the fifth edition. With the development of new diagnostic methods, based on genetic alterations, it provides insight into the molecular basis of lesions. This has resulted in the evolution of classification, introduction of new entities and reclassification of existing ones.

CONCLUSIONS

Genetic alterations will become increasingly more significant in the identification of salivary gland pathologies in the future. These alterations will be helpful as prognostic and predictive biomarkers, and may also serve as targets for anti-cancer therapies.

A rare case of canalicular adenoma in the parotid gland: Highlighting diagnostic limitations of fine-needle aspiration

BACKGROUND

Canalicular adenoma is a rare, benign tumor of primarily salivary gland origin that presents mostly in the upper lip. However, there are only six reports in the English literature detailing canalicular adenoma of the parotid gland, none of which discuss discrepancy between preoperative cytology and surgical pathology. In this report, we present a rare case of parotid gland canalicular adenoma where preoperative ultrasound-guided fine-needle aspiration (USFNA) suggested malignancy. The patient was treated with deep lobe parotidectomy due to the FNA results and her multiple comorbidities. However, her tumor may have been treated with observation alone if canalicular adenoma had been suspected prior to surgery.

MAIN FINDINGS

A 59-year-old female with a history of heart and lung disease presented with a 1.6 cm well defined, enhancing lesion involving the superficial portion of the right parotid gland. This lesion was incidentally noted on CT angiography (CTA) of the neck and chest. The well-defined characteristics of this lesion on CT imaging suggested benign neoplasm. However, USFNA results were suggestive of a malignant parotid lesion. The patient subsequently underwent right deep lobe parotidectomy with facial nerve dissection and superficial musculoaponeurotic system (SMAS) rotational flap reconstruction. Surgical pathology and immunohistochemistry yielded a final diagnosis of benign canalicular adenoma.

CONCLUSIONS

USFNA diagnosis of CA is extremely difficult due to its low-grade neoplastic cells mimicking neoplastic cells in other benign and malignant tumors of the head and neck. FNA remains a useful tool for assessing malignancy risk, but the results always have some level of uncertainty and do not provide sufficient detail. Therefore, FNA results should be interpreted in concert with imaging and patients' medical history. Cytopathologists can also report salivary gland FNA results in a more uniform and detailed manner by utilizing the Milan System for Reporting Salivary Gland Cytopathology (MSRSGC).

Recurrent IDH2 Mutations in Salivary Gland Striated Duct Adenoma Define an Expanded Histologic Spectrum Distinct From Canalicular Adenoma

Striated duct adenoma (SDA) is a rare salivary gland neoplasm defined by histologic similarity to normal striated ducts. However, doubt persists about whether SDA represents a genuine entity distinct from canalicular adenoma and if a malignant counterpart exists. This study aims to evaluate the molecular underpinnings of SDA to clarify its pathogenesis and classification. We identified 10 SDA and 2 tumors called low-grade adenocarcinoma not otherwise specified that were retrospectively recognized to resemble SDA. All cases showed recurrent histologic features including (1) discrete monophasic tubules, (2) tall columnar eosinophilic cells, (3) monotonous oval nuclei, and (4) scant fibrous stroma, and most were positive for S100 protein (91%), SOX10 (80%), and CK7 (80%). Although 1 case was previously called adenocarcinoma based on interdigitation with normal acini, this pattern was also seen in some SDA, and likely does not indicate malignancy; the significance of growth surrounding nerve in 1 other case is less clear. Targeted sequencing identified IDH2 R172X mutations in all 8 cases with sufficient tissue, with positivity for IDH1/2 mutation-specific immunohistochemistry in 9 cases stained. In contrast, 5 canalicular adenomas lacked IDH2 mutations or other oncogenic alterations. Overall, IDH2 R172X mutations are a defining feature of SDA that, in combination with its recognizable pathologic profile, confirm it is a unique entity separate from canalicular adenoma. IDH1/2 mutation-specific immunohistochemistry may provide a convenient tool to facilitate diagnosis. Both morphology and IDH2 mutations raise parallels between SDA and breast tall cell carcinoma with reverse polarity.

HMGA2-WIF1 Rearrangements Characterize a Distinctive Subset of Salivary Pleomorphic Adenomas With Prominent Trabecular (Canalicular Adenoma-like) Morphology

Most of salivary gland neoplasms (benign and malignant) are characterized by recurrent gene fusions. Pleomorphic adenoma (PA), the most frequent salivary gland tumor, is driven by chromosomal rearrangements involving PLAG1 mapped to 8q12 and HMGA2 mapped to 12q13-15 in most cases. Multiple fusion partners have been identified including CTNNB1, FGFR1, LIFR, CHCHD7 and TCEA for PLAG1 fusions and NFIB, WIF1 and FHIT for HMGA2 fusions. To date, no data exist on the morphology of the few reported HMGA2-WIF1-rearranged PAs. We present 28 major salivary gland adenomas displaying distinctive trabecular and canalicular morphology associated with recurrent genotype. Patients were 15 females and 13 males aged 43 to 87 (median: 65). All tumors originated from the parotid. Their size range was 1 to 4 cm (mean: 2.3). Histologically, all tumors showed elongated or columnar cells arranged into bilayered to multilayered communicating and branching strands and trabeculae in a manner similar to canalicular adenoma of minor salivary glands or trabecular myoepithelioma with variable solid confluent intercalated duct-like areas. Fifteen tumors were exclusively canalicular/trabecular while 13 had intermingled or well-demarcated conventional (chondromyxoid) PA component comprising 5 to >50% of the tumor. The monomorphic areas expressed uniformly CK7 (28/28), vimentin (21/21), S100 (24/24), SOX10 (16/17) and variably p63 (8/21) and mammaglobin (6/16) but were negative with p40 (0/24), smooth muscle actin (0/24) and MUC4 (0/16). Targeted RNA sequencing revealed HMGA2 fusions in 14/16 (87%) assessable cases. Fusion partner was WIF1 (12), RPSAP52 (1) and HELB (1). Separate testing of the 2 components in 1 hybrid tumor showed same HMGA2/WIF1 fusion. HMGA2 immunohistochemistry was homogeneously positive in all cases including the 2 fusion-negative cases. A control cohort of 12 genuine canalicular adenomas revealed no HMGA2 fusions (0/4) and lacked HMGA2 immunoreactivity (0/12). This study highlights a distinctive variant in the spectrum of PA characterized by prominent trabecular and canalicular adenoma-like morphology. Our data confirm that canalicular adenomas in major salivary glands (either monomorphic or part of hybrid tumors) are distinct from canalicular adenoma of minor salivary glands. Their uniform genotype irrespective of presence or absence of a conventional PA component argues for classifying those tumors lacking a conventional PA component as "monomorphic variants of PA" rather than canalicular/basal cell adenomas, intercalated duct adenoma, trabecular myoepithelioma or true hybrid tumors.

A case of canalicular adenoma with anemia

An 81-year-old woman presented with bleeding from a soft elastic bulge on the right buccal mucosa. Her medical history included hypertension, chronic renal failure, hysterectomy and a goiter operation. Certain investigations, such as blood tests, which confirmed the minimum hemoglobin level of 5.3 g/dl, computed tomography and magnetic resonance imaging (MRI), were conducted. MRI revealed features confirming the presence of a tumor involving the right buccal mucosa with high signal in T2-enhanced image. Considering the provisional diagnosis and image findings, the tumor mass was excised and histopathological examination of the biopsy specimen confirmed the diagnosis of a canalicular adenoma. Under the diagnosis of various clinical departments, the anemic state of the patient might be chiefly attributed to the bleeding from the tumor. Herein, we report a rare case of a canalicular adenoma in the right buccal mucosa with anemia due to bleeding from the tumor.

Pleomorphic adenoma of the breast with cytologic atypia on cytopathology: A potential diagnostic pitfall and literature review

Pleomorphic adenoma of the salivary gland is a well-established and recognized diagnosis; however, pleomorphic adenomas of the breast are rare and can be difficult to diagnose on cytology or intraoperatively. We report a case that was misdiagnosed on a fine needle aspiration and frozen section. The pitfalls, differential diagnoses, and current management are discussed.

Practical immunohistochemistry in the classification of salivary gland neoplasms

Diagnosis of salivary gland neoplasms can be challenging for surgical pathologists due to low incidence of tumors as well as overlapping histologic features. On small biopsy, the most important information to be conveyed for clinical management is the distinction between a benign/low grade tumor and a high grade carcinoma. This review will discuss the differential diagnosis of salivary gland tumors based on four broad morphologic patterns: basaloid/tubular/cribriform, (micro)cystic/secretory/mucinous, solid-nested/clear-spindled, and oncocytic/oncocytoid. With the assistance of immunohistochemistry, demonstration of the number of cell types (mainly epithelial versus myoepithelial/basal) can further subclassify tumors within these morphologic categories. Additional tumor-specific immunomarkers are useful in some cases. Underlying tumor-specific genetic anomalies can be of value, however, immunohistochemical correlates are only available for some. When used judiciously, in the correct morphologic context, and with knowledge of their limitations, immunohistochemical stains can aid in differentiating tumors with similar morphology.

Canalicular adenoma: palatal presentation of an uncommon lesion

Canalicular adenoma is a unique, rare, benign salivary gland neoplasm whose reported prevalence varies in different studies. According to literature, this neoplasm has a marked predilection to occur in the upper lip of elderly women. Histological features are usually distinctive and diagnostic. This neoplasm has good prognosis after conservative surgical management but the propensity of multifocal nature and recurrence of this lesion mandates regular follow-up. This case report illustrates the case of a canalicular adenoma in the palate in a 71-year-old male patient. Here, we discuss the differential diagnosis with a brief review of literature.

Oncocytic Polyp in a Unicystic Mucoepidermoid Carcinoma of the Palate: A Unique Presentation

We report a palatal mucoepidermoid carcinoma (MEC) with unusual pathological features showing salivary duct cyst-like architecture, varied epithelial linings (excretory duct, mucous goblet cell, and apocrine epithelium phenotypes), scarce luminal tumor plaques, and a large intraluminal oncocytic polyp. To our knowledge, such a unicystic variant of MEC with pedicled oncocytic proliferation in the lumen is unprecedented in the literature. In this particular case, the microscopic diagnosis of MEC is problematic because of the large number of potential mimics.

Canalicular adenoma of the tongue: report of a unique case

Canalicular adenoma (CA) is a rare, unique benign salivary gland neoplasm, which usually involves the minor salivary glands of the upper lip, buccal mucosa and palate. It is usually seen in middle-aged or older individuals, has a female predilection, and commonly presents as a painless, slow-growing, non-ulcerated nodule or swelling. Its treatment involves surgical excision or enucleation. This case report describes a case of CA of the ventrum of the tongue diagnosed in a 41-year-old male patient, which could possibly be the first reported case of this lesion involving the tongue.

Canalicular adenoma of the hard palate: A rare case report

Canalicular adenoma (CA) is a rare, benign salivary gland tumor that has special tendency to occur in the upper lip. Buccal mucosa is the second most common site. It occurs more often in older patients with peak prevalence in the seventh decade of life. A definitive female predominance has been reported. According to the latest English published literature, 531 cases of CA have been reported. We present a case of CA of the hard palate that presented in a 29-year-old female patient. The histopathological and immunohistochemical findings showed typical features of CA and intense expression of pan-cytokeratin and S-100 protein. We also review its differential diagnosis from other salivary gland tumors.

Synchronous Multifocal Canalicular Adenomas

Canalicular adenoma (CAD) is an uncommon benign tumor of minor salivary glands with predilection for the upper labial mucosa. An 80-year-old female presented with nine submucosal nodules of the upper labial mucosa and bilateral buccal mucosa. Histopathologic examination revealed multifocal circumscribed tumor islands with a tubular growth pattern within a loose hypocellular myxoid background stroma. Interconnecting rows of columnar tumor cells imparted a canalicular morphology. In addition to the characteristic histopathologic findings, a comprehensive immunohistochemical panel supported a final diagnosis of multifocal CAD. Synchronous multifocality in CAD is an infrequent finding and this sine qua non clinicopathologic correlation article exemplifies such a case.

Canalicular adenoma with unicystic morphology. A rare entity

Background

Canalicular adenoma (CA) is a benign salivary gland tumor (SGT) almost exclusively affecting the minor salivary glands, predominantly of the upper lip, and exhibiting characteristic histopathologic features. As observed in several other SGTs, a commonly encountered finding is the presence of prominent cystic morphology. Even though a multicystic appearance is usually noticed, solitary cystic CAs may rarely occur.

Case Report

Two female patients (74 and 78 years old respectively) presented for the evaluation of submucosal asymptomatic masses of the oral cavity. In the 1st case a solitary nodule was noticed in the upper lip, while the 2nd patient exhibited two symmetrical lesions of the buccal mucosae. All three excised specimens displayed cystic morphology upon gross examination. Histopathologically, a solitary cystic formation lined by monomorphic cuboidal or basaloid cells arranged in solid or trabecular patterns was observed in the 1st case. With a differential diagnosis of CA vs basal cell adenoma immunohistochemical examination was performed. Positivity for S-100, CK7 and CD117 (c-kit) and negative reaction for GFAP, p63 and SMA rendered the diagnosis of CA. In the 2nd case both lesions displayed well-circumscribed proliferations by monotonous cuboidal or columnar cells arranged in single cords and occasionally forming beading patterns, while central solitary areas of marked cystic degeneration were noticed. Diagnosis of multifocal unicystic CA was disclosed.

Discussion

To our knowledge, only 11 additional cases of unicystic CA have been reported in the English-language literature. Although the exact clinical significance of unicystic morphology in CA is unknown, a tendency for occurrence within the context of multifocal tumors has been detected.

Key words:Canalicular adenoma, monomorphic adenoma, unicystic morphology, multifocal tumors, minor salivary glands.

Psammoma Bodies in a Large Myoepithelioma

Myoepithelioma is a rare benign tumor of the salivary glands, in which the vast majority of neoplastic cells are myoepithelial. A rare microscopic finding in salivary gland tumors, including myoepitheliomas, is the presence of psammoma bodies (PBs), whose etiology and role in the tumors are uncertain. The objective of this study is to describe the unusual histopathologic findings, such as psammomas, of a large myopephelioma on the palate and the prosthetic restorative treatment performed after resection of the tumor. A 52-year-old woman was referred for evaluation of a tumor-like lesion, of smooth surface and normal mucosal color, measuring approximately 5 cm, on the left side hard palate, which had been identified 4 years earlier. The diagnostic hypothesis was a pleomorphic adenoma (PA), and an incisional biopsy was performed. After histopathologic analysis, a PA was suggested, and surgical resection of the tumor was performed. The histopathologic findings were compatible with myoepithelioma showing numerous calcified basophilic structures compatible with PB. Sixteen months after resection of the tumor, a removable maxillary obturator prosthesis was made because of the communication into oral and nasal cavity due from the surgical procedure. The treatment of choice for myoepithelioma is surgical excision with a nonlesional area margin. In the present report, the authors achieve good postoperative results without recurrences. After installation of the prosthesis, the patient had an excellent adaptation and acceptance, thus restoring her function and psychologic condition.

Navigating small biopsies of salivary gland tumors: a pattern-based approach

Diagnosis of salivary gland tumors on small biopsy can be difficult because of overlapping morphology, limited tissue availability, and technical artifact. Although a specific diagnosis is not feasible in all cases, a cautious and thoughtful approach to the differential diagnosis and a keen awareness of clinical consequences can facilitate the most complete and useful classification possible. In this review, we present a general strategy for the evaluation of small salivary biopsies, including consideration of clinical and radiographic information, systematic assessment of histologic patterns, and judicious use of immunohistochemistry and molecular studies. We then focus on the distinctive differential diagnoses raised by 6 specific histologic patterns: tubular and cribriform architecture, squamous differentiation, mucin and other secretions, high-grade cytology, epithelial and lymphoid elements, and oncocytic features. Throughout this systematic and pattern-based approach, we focus on practical and cost-effective strategies to overcome the most common diagnostic challenges in limited material.

Analysis of the Clinical Relevance of Histological Classification of Benign Epithelial Salivary Gland Tumours

INTRODUCTION

A vast increase in knowledge of numerous aspects of malignant salivary gland tumours has emerged during the last decade and, for several reasons, this has not been the case in benign epithelial salivary gland tumours. We have performed a literature review to investigate whether an accurate histological diagnosis of the 11 different types of benign epithelial salivary gland tumours is correlated to any differences in their clinical behaviour.

METHODS

A search was performed for histological classifications, recurrence rates and risks for malignant transformation, treatment modalities, and prognosis of these tumours. The search was performed primarily through PubMed, Google Scholar, and all versions of WHO classifications since 1972, as well as numerous textbooks on salivary gland tumours/head and neck/pathology/oncology. A large number of archival salivary tumours were also reviewed histologically.

RESULTS

Pleomorphic adenomas carry a considerable risk (5-15%) for malignant transformation but, albeit to a much lesser degree, so do basal cell adenomas and Warthin tumours, while the other eight types virtually never develop into malignancy. Pleomorphic adenoma has a rather high risk for recurrence while recurrence occurs only occasionally in sialadenoma papilliferum, oncocytoma, canalicular adenoma, myoepithelioma and the membranous type of basal cell adenoma. Papillomas, lymphadenoma, sebaceous adenoma, cystadenoma, basal cell adenoma (solid, trabecular and tubular subtypes) very rarely, if ever, recur.

CONCLUSIONS

A correct histopathological diagnosis of these tumours is necessary due to (1) preventing confusion with malignant salivary gland tumours; (2) only one (pleomorphic adenoma) has a considerable risk for malignant transformation, but all four histological types of basal cell adenoma can occasionally develop into malignancy, as does Warthin tumour; (3) sialadenoma papilliferum, oncocytoma, canalicular adenoma, myoepithelioma and Warthin tumour only occasionally recur; while (4) intraductal and inverted papilloma, lymphadenoma, sebaceous adenoma, cystadenoma, basal cell adenoma (apart from the membranous type) virtually never recur. No biomarker was found to be relevant for predicting recurrence or potential malignant development. Guidelines for appropriate treatment strategies are given.

Challenges in Minor Salivary Gland Biopsies: A Practical Approach to Problematic Histologic Patterns

Evaluation of minor salivary gland biopsy can be fraught with a wide range of problems, including technical limitations due to the small size and distorted nature of tissue received and interpretive difficulties navigating the considerable morphologic and immunohistochemical overlap between widely disparate entities. As such, common pathologic findings can evoke a perplexing differential diagnosis that encompasses malignant, benign, and non-neoplastic processes. This review will present the diagnostic considerations that arise from four histologic patterns that are frequently encountered on minor salivary gland biopsies: squamous differentiation, tubular and cribriform growth, mucin production, and myxoid stroma. The discussion herein will emphasize practical strategies and priorities for navigating these differential diagnoses in a clinically-relevant and cost-effective manner.

Pleomorphic Adenoma of the Upper Lip: A Case Report

Pleomorphic adenoma is the most frequently encountered benign mixed tumor of the minor salivary gland and usually presents in the parotid; however, in the minor salivary gland, it is more common in the palate. Tumors of the minor salivary glands are uncommon, with the most common intraoral site reported being the hard and soft palate owing to the preponderance of minor salivary glands in this region followed by the lips. Pleomorphic adenoma arising from minor salivary glands of the lips tends to occur at an earlier age than it does at other sites. Pleomorphic adenoma of the lip is a rare neoplasm, and thus its diagnosis requires a high index of suspicion and a long-term follow-up. Here, the authors present a case of pleomorphic adenoma of the upper lip.

Canalicular adenoma: A systematic review

OBJECTIVE

Canalicular adenoma (CA) is an uncommon but unique benign tumor of salivary gland origin. It is the third most common benign tumor of minor salivary glands, representing less than 1% of all salivary neoplasms. A systematic review is presented of reported cases of CA, to determine trends in presentation, diagnostic features, treatment, and patient outcome.

METHODS

Searches of specific databases, as reported, were carried out to identify papers reporting CA. The variables were patient symptoms, tumor location, histopathological findings, demographics, treatment, follow-up, and recurrence.

RESULTS

430 cases were identified; the most common location was in the upper lip (66.3%), followed by hard palate (14.5%). The most common clinical presentation was a nodule (46.5%), followed by asymptomatic (29.5%), and discomfort (28.7%). CA was most frequently seen in females (64%). The average age was 66.3 years. 97% of cases were treated surgically. The average follow-up was 136.3 months, and recurrence was reported in 3% of the cases.

CONCLUSION

CA shows a strong predilection for the upper lip. CAs are frequently asymptomatic, but the principal symptom was pressure.

Synchronous Polymorphous Adenocarcinoma and Canalicular Adenoma on the Upper Lip: An Unusual Presentation and Immunohistochemical Analysis

Multiple salivary gland tumors (MSGTs) are most common in the major than minor salivary glands. The most MSGTs are synchronous, either benign or malignant. A 61-year-old woman was referred presenting nine submucosal nodules, firm to fluctuant, being five nodules on the right side and four nodules on the left side of the upper lip. An incisional biopsy was performed. Hematoxylin and eosin staining was performed in 5-µm sections for histopathologic analysis. Immunohistochemical reactions were carried out in 3-µm sections in accordance with manufacturer's instructions. The histopathological analysis showed focal area containing low-grade polymorphous adenocarcinoma (PAC) and multiple canalicular adenomas (CAs). Immunohistochemical analysis for each lesion was carefully investigated. Here, we present an unusual case of synchronous PAC and multiple CAs of the minor salivary glands, affecting the upper lip, which appears to be the first case showing PAC and CA.

Angioleiomyoma of the upper lip

This report describes a case of labial angioleiomyoma in a 52-year-old woman. The patient had noticed a slow-growing painless isolated mass in her upper lip for 6 months. The mass was surgically excised, and pathological examination was consistent with angioleiomyoma. Surgical excision was curative, and there was no recurrence at 12-month follow-up.

Striated duct adenoma presenting with intra-tumoral hematoma and papillary thyroid carcinoma-like histology

Striated duct adenoma of the salivary gland is a rare benign tumor characterized by unilayered duct epithelium and striations of the tumor cell membranes. To the best of our knowledge, only six cases have been reported in the literature. Here we report an additional case, which was complicated by an intra-tumoral hematoma on clinical presentation and by papillary thyroid carcinoma-like histology on intra-operative frozen section diagnosis. An asymptomatic 78-year-old male presented with a two-year-history of a painless tumor of the left parotid. An intra-tumoral hematoma, which is unusual for a salivary gland tumor, was suspected from results of pre-operative radiology. The patient then underwent a left parotidectomy. The intra-operative frozen section diagnosis indicated a benign tumor, although ectopic papillary thyroid carcinoma was raised as a differential diagnosis since the eosinophilic tumor cells occasionally possessed nuclear grooves and nuclear pseudo-inclusions. By precise histopathological examination using paraffin sections, the tumor was finally diagnosed as striated duct adenoma. This type of tumor has unique features of hypervascular stroma and papillary thyroid carcinoma-like nuclei. In our case, the former feature was associated with the intra-tumoral hematoma and the latter feature, with difficulty in frozen section tumor diagnosis.