Clinical and therapeutic features of polymorphous low-grade adenocarcinoma

Polymorphous adenocarcinoma of minor salivary gland: Case presentation and literature review

INTRODUCTION AND IMPORTANCE

Polymorphous low-grade adenocarcinoma (PLGA) is a rare neoplasm arising from minor salivary glands, representing approximately 3 % of head and neck tumors. The clinical presentation of PLGA is defined as a painless, slow-growing tumor, mostly occurring in the palate. We report a case of PLGA with a rare presentation.

CASE PRESENTATION

A 76-year-old male, known case of hepatitis B, diabetes, and hypertension, presented to the emergency department complaining of spitting blood and dysphagia. Imaging showed a heterogeneous enlarged left tonsil with hyperemia of the mucosa, and air foci. Biopsy with excisional biopsy confirmed the diagnosis of PLGA. The patient underwent completion tonsillectomy and selective neck dissection which yielded tonsillar tissue with underlying PLGA, and reactive lymph nodes with no malignant tissue respectively, margins were negative for malignancy.

CLINICAL DISCUSSION

Polymorphous low-grade adenocarcinoma is a rare lesion with clinical behavior resembling that of a benign neoplasm. Predominantly occurring in the oral cavity, especially on the hard palate, buccal mucosa, and retromolar region, with fewer cases in the upper lip. Occurrence in the nasopharynx and oropharynx is rare. PLGA presents as painless slow-growing masses, typically in females aged 50-60. Local excision with careful margin evaluation is the preferred treatment, with good prognosis compared to other carcinomas.

CONCLUSION

PLGA is rare, with limited reported case from around the world. It is mostly seen in adults between their fifth and sixth decades with female predominance. PLGA is diagnosed using imaging, immunohistochemistry. Owing to the limited cases there is no standard approach to treating PLGA. However, most cases are managed with local excision and showed an excellent response in terms of tumor nonrecurrence.

Polymorphous Adenocarcinoma: A Rare Case Report with Unique Radiographic Appearance on CBCT

BACKGROUND

Polymorphous low-grade adenocarcinoma (PLGA) is a slow growing malignant tumor of minor salivary glands and is generally of indolent nature. However, according to the most recent WHO Classification of Salivary Gland Tumors (2017), the cancer is classified as Polymorphous AdenoCarcinoma (PAC). PAC presents as a less aggressive tumor, though it could on rare occasions demonstrate distant metastasis. Case Presentation. A 47-year-old man who was referred by a private practitioner for a CBCT scan in reference to a proliferative soft-tissue growth in the hard palate. The growth was mild and tender and there was Grade III mobility in relation to all the maxillary teeth. Panoramic radiograph taken previously had revealed evidence of alveolar bone loss in relation to the maxillary teeth and was inconclusive of any other findings. The CBCT scan revealed evidence of moth-eaten appearance of maxilla with destruction of medial and lateral walls and floor of maxillary sinus. There was also evidence of involvement of right eustachian tube, ethmoidal wall, and nasopalatine canal. An intraosseous malignancy of the palate was suspected, and a total maxillectomy was performed. The tissue sample was sent for histopathological assessment wherein changes diagnostic for polymorphous low-grade adenocarcinoma of the palate were observed.

CONCLUSION

PAC is a distinct, yet commonly occurring, minor salivary gland tumor with varied clinical and histologic appearance. This case report highlights the importance of CBCT in diagnosing the intraosseous involvement of such tumors which can help shed some light in enhancing our knowledge about the minor salivary gland malignancies like PAC.

Polymorphous Adenocarcinoma

Polymorphous adenocarcinoma (PAC) is typically originated from the minor salivary glands and is characterized by cytology uniformity and architectural diversity. PAC commonly harbors PRKD1 E710D mutation. PAC has an excellent prognosis. However, greater than or equal to 10% papillary or greater than or equal to 30% cribriform pattern is an independent adverse prognostic factor. Cribriform adenocarcinoma of salivary gland (CASG) is a controversial entity that is considered within the same histologic spectrum of PAC in current classification schemes; however, it is regarded by some pathologists as a separate entity. CASG shows a propensity to base of tongue location, a lobulated growth pattern, a predominant solid/cribriform architecture, and a high frequency of PRKD1/2/3 fusion.

Autophagy and salivary gland cancer: A putative target for salivary gland tumors

Salivary gland carcinomas are a group of heterogeneous tumors of different histological subtypes, presenting relatively low incidence but the entire variable of types. Although novel treatment options for salivary gland carcinomas patients' outcomes have improved, the treatment of this type of cancer is still not standardized. In addition, a significant number of patients, with a lack of optimal treatment strategies, have reduced survival. In the last two decades, a plethora of evidence pointed to the importance of autophagy, an essential catabolic process of cytoplasmatic component digestion, in cancer. In vitro and in vivo studies highlight the importance of autophagy in salivary gland carcinomas development as a tumor suppressor or promoter mechanism. Despite the potential of autophagy in salivary gland carcinomas development, no therapies are currently available that specifically focus on autophagy modulation in salivary gland carcinomas. In this review, we summarize current knowledge and clinical trials in regard to the interplay between autophagy and the development of salivary gland carcinomas. Autophagy manipulation may be a putative therapeutic strategy for salivary gland carcinomas patients.

Polymorphous adenocarcinoma of the salivary glands: reappraisal and update

Although relatively rare, polymorphous adenocarcinoma (PAC) is likely the second most common malignancy of the minor salivary glands (MiSG). The diagnosis is mainly based on an incisional biopsy. The optimal treatment comprises wide surgical excision, often with adjuvant radiotherapy. In general, PAC has a good prognosis. Previously, PAC was referred to as polymorphous low-grade adenocarcinoma (PLGA), but the new WHO classification of salivary gland tumours has also included under the PAC subheading, the so-called cribriform adenocarcinoma of minor salivary glands (CAMSG). This approach raised controversy, predominantly because of possible differences in clinical behaviour. For example, PLGA (PAC, classical variant) only rarely metastasizes, whereas CAMSG  often shows metastases to the neck lymph nodes. Given the controversy, this review reappraises the definition, epidemiology, clinical presentation, diagnostic work-up, genetics, treatment modalities, and prognosis of PAC of the salivary glands with a particular focus on contrasting differences with CAMSG.

Palatal Polymorphous Adenocarcinoma with High-Grade Transformation: A Case Report and Literature Review

Polymorphous adenocarcinoma (PAC) is the second most common intraoral malignant neoplasm of the minor salivary glands. However, it is very rare for PAC to show high-grade transformation (HGT) and to our knowledge, the English literature only seven reported cases. HGT tends to be observed when PAC recurs, and it is extremely rare to be seen at initial presentation. Here we report a 43-year-old Japanese male patient with PAC of the right palate showing HGT at initial presentation. Histopathologically, the tumor was characterized by a prominent solid and papillary-cystic growth pattern, with nuclear atypia and necrosis in area of HGT. The immunohistochemical staining pattern was consistent with PAC, as the tumor cells showed diffuse positivity for cytokeratin, vimentin and S-100, and focal positivity for bcl-2, ɑ-SMA and EMA. The tumor cells in HGT areas were markedly positive for AR and Ki-67 (about 40%/HPF), and also focally positive for cyclin D1 and p53, whereas HER2/neu, ER, PgR, p63, D2-40, GCDFP-15, and mitochondria were negative. Here we present a very rare case of palatal PAC with HGT at initial presentation.

Current State of Knowledge on Salivary Gland Cancers

Salivary gland cancers (SGCs), categorized as head and neck cancers (HNCs), constitute about 6% of head and neck cancer diagnoses based on estimate by American Head and Neck Society. Salivary gland tumors originate from different glandular cell types and are thus morphologically diverse. These tumors arise from any of the three major and various minor salivary glands. The incidence of SGCs has slowly increased during the last four decades. The etiology of SGCs is mostly unknown; however, specific gene mutations are associated with certain types of salivary tumors. Treatment options include surgical resection, radiation therapy (RT), chemotherapy, and multimodality therapy. HNC patients treated with RT often develop xerostomia and salivary hypofunction due to damaged salivary glands. In this review, we discuss etiology of SGCs, present findings on the role of autophagy in salivary tumorigenesis, review adverse effects of radiation treatment, and examine remedies for restoration of salivary function.

Plasmacytoid-Type Cellular Differentiation in Polymorphous Low-Grade Adenocarcinoma

INTRODUCTION

Polymorphous low-grade adenocarcinoma (PLGA) occurs more frequently in minor salivary glands. The diagnosis of PLGA, in general, is not difficult but in occasional tumors showing limited invasion or in small biopsy specimens, PLGA may be confused with cellular pleomorphic adenoma (PA). Plasmacytoid cells, a usual component of PAs, have been considered helpful for correct tumor identification.

OBJECTIVE

The aim of this study was to verify the frequency (if any) of plasmacytoid-type cellular differentiation (PD) in PLGA.

MATERIALS AND METHODS

Thirty-two cases of PLGA were reviewed. PD was recognized in 2 cases (6.25%), in which immunohistochemical expression of AE1/AE3, CK7, CK14, vimentin, α-SMA, p63, S-100, calponin, GFAP, and Ki-67 was evaluated.

RESULTS

The 2 cases presented conventional areas of PLGA and variable quantities of cells with PD forming aggregates in the stroma and lining ductal structures. Cells with PD showed positivity for AE1/AE3, CK7, S-100, and vimentin and were negative for CK14, calponin, and GFAP in both cases. In case 1, cells with PD did not present α-SMA and p63 positivity whereas in case 2 they were positive, but for α-SMA such reactivity was restricted to cells forming solid aggregates.

CONCLUSION

Although PD in PLGA is rare, it is necessary to be aware of this possibility, particularly in small incisional biopsies and in PLGA with limited invasion, to avoid confusion with cellular PA.

Polymorphous low-grade adenocarcinoma of the upper lip: 11 cases of an uncommon diagnosis

OBJECTIVE

The aim of this case study was to describe an international case series of polymorphous low-grade adenocarcinoma (PLGA) affecting the upper lip.

MATERIAL AND METHODS

Over a 30-year-period, the files of five pathology services were reviewed for PLGA affecting the upper lip. Hematoxylin and eosin-stained slides were reviewed by three oral and maxillofacial pathologists, and microscopic features were described. Clinical data were retrieved from patients' medical records.

RESULTS

The review identified 11 cases of upper lip PLGAs, with a complete set of clinical data available for 5 cases. There was a male predominance (1.2:1), and the mean age was 58.7 years. Most cases presented as small asymptomatic swellings that resembled benign tumors. All patients underwent surgery, and no recurrences or metastases were reported in the 8 cases from which follow-up data were available. Microscopically, the typical polymorphic architectural arrangement of PLGA was seen in all cases, with lobular, trabecular, papillary, and cribriform patterns identified. Perineural invasion, normal gland entrapment, Indian filing, and concentric growth were frequently identified.

CONCLUSION

PLGA must be included in the list of differential diagnoses of tumors affecting the upper lip because of its similar clinical presentation to benign entities. The follow-up data available from 8 of 11 cases suggest that these tumors follow a low-grade clinical course, similar to the majority of palatal cases of PLGA.

Not just another paediatric neck lump: metastatic cribriform adenocarcinoma of the palate in an adolescent

Objective:

This paper reports the case of a 13-year-old girl with a 2-year history of left cervical lymph node swelling that was diagnosed as metastatic cribriform adenocarcinoma of the tongue and minor salivary gland.

Case report:

A 13-year-old girl with a left, level II cervical lymph node underwent excisional biopsy after an ultrasound suggested suspicious features. The histology indicated polymorphous low-grade adenocarcinoma, and a primary lesion in the left palate was identified. The patient underwent left maxillectomy, neck dissection and reconstruction. Histological analysis of resection specimens led to a revised diagnosis of cribriform adenocarcinoma of the tongue and minor salivary gland.

Conclusion:

Cribriform adenocarcinoma of the tongue and minor salivary gland has recently been described as a separate entity to polymorphous low-grade adenocarcinoma in light of histological and behavioural differences, including higher rates of metastasis at presentation. This is the first report in the world literature of an adolescent with this entity. It is possible that some previous reports of polymorphous low-grade adenocarcinoma in childhood would have been more accurately described as cribriform adenocarcinoma of the tongue and minor salivary gland.

Polymorphous Low-Grade Adenocarcinoma of the Palate: A Rare Case Report

Introduction

Polymorphous low-grade adenocarcinoma (PLGA) has been known as a comparatively less aggressive malignant tumor that predominantly occurs in the minor salivary glands. It has presented as a painless, slow growing tumor in the oral cavity. It has been reported to occur rarely in the palate and the prognosis of this lesion is far better than adenocarcinoma as the regional metastasis would be very minimal. A clear difference between the biologic behaviors of adenocarcinoma and PLGA has been reported in literature.

Case Presentation

A 63-year-old female reported at our institute with a swelling in relation to her upper left back region of her jaw for three months, gradual in onset and associated with pain. After clinical and radiological examination, the differential diagnosis were consolidated abscess or minor salivary gland tumor. An incisional biopsy was done and the lesion was diagnosed as PLGA. The lesion was treated by wide excision and reconstruction with immediate obturator. The post-operative follow up showed no evidence of recurrence and the healing was satisfactory.

Conclusions

The site of predilection of PLGA is more in favor of palate (49 - 77.8%) followed by either upper lip or buccal mucosa (7.4 - 13.4%). There are sporadic reports of metastasis sometimes even transformation to a high grade adenocarcinoma, sometimes ending in mortality. Cervical lymph node metastasis is rare with reported incidence of 5 - 15% and is more commonly seen in recurrent tumor than the initial diseases. Extra palatal PLGAs present with significant papillary growth or arising from ventral surface of tongue frequently metastasize to cervical lymph nodes. Distant metastasis is very rare with an incidence of 7.5% and the site involved is the lung which is attributed to the inadequate control of the disease.

Polymorphous low-grade adenocarcinoma of the head and neck

Polymorphous low-grade adenocarcinomas are rare tumors that can arise from many areas of the head and neck. We reviewed the pertinent literature pertaining to the incidence, diagnostic evaluation, and treatment strategies for this malignancy. Histopathologic diagnosis always involves careful analysis of tissue and especially characteristic immunohistochemical staining patterns. Common differential diagnoses include adenoid cystic carcinoma, pleomorphic adenoma, and other benign or malignant salivary gland neoplasms. Although the ideal treatment is debated, surgical resection at times combined with adjuvant radiation therapy is preferred by many physicians. Further research will be needed to delineate optimal management.

Surface Papillary Epithelial Hyperplasia (Rough Mucosa) is a Helpful Clue for Identification of Polymorphous Low-Grade Adenocarcinoma

The purpose of this study is to evaluate surface papillary epithelial hyperplasia, a microscopic finding that corresponds to the clinical finding of rough or stippled mucosa, as a predictor of polymorphous low-grade adenocarcinoma (PLGA). We conducted a retrospective review of minor salivary gland neoplasms submitted to our biopsy service from 1991 to 2013. Our review was limited to lesions involving the oral cavity/soft palate with the following diagnoses: PLGA, pleomorphic adenoma (PA), mucoepidermoid carcinoma (MEC), and adenoid cystic carcinoma (ACC). A total of 202 minor salivary gland neoplasms were included in the study. Among cases in which surface epithelium was present for evaluation (n = 112), surface papillary epithelial hyperplasia was evident in 30 % of PLGA and 1 % of non-PLGA (i.e., MEC, ACC, PA). The greater frequency of surface papillary epithelial hyperplasia in the PLGA versus non-PLGA cases and in the benign versus malignant cases was significant (p = .0001 and p = .041, respectively). The sensitivity and specificity of papillary epithelial hyperplasia for PLGA were 30 % (95 % confidence interval (CI) 11.97-54.27 %) and 99 % (95 % CI 94-99.82 %), respectively. The clinical presentation of PLGA appeared relatively nonspecific, with all analyzed tumor types exhibiting a predilection for females, middle-aged to older adults, palatal location, pink/tan/normal color, and firm consistency. In conclusion, papillary epithelial hyperplasia was evident in only a minority of PLGA. However, when present within the context of a palatal salivary gland neoplasm, it appears to indicate a high probability of PLGA. Accordingly, rough mucosa may be a useful clinical pearl for identification of PLGA.

Proton beam therapy and continuous intra-arterial chemotherapy for polymorphous low-grade adenocarcinoma in the hard palate

Polymorphous low-grade adenocarcinoma is a rare malignant tumor that mainly occurs in salivary glands, particularly in the hard palate. To date, surgery has been the most commonly used treatment method with the aim of achieving negative margins of resection. Here, we report a case of a 51-year-old woman who presented with a painless growing mass in her oral cavity with Rouviere's lymph node metastasis. Laboratory data showed severe anemia because of bleeding from the tumor. We inserted two catheters into the bilateral external carotid arteries via the superficial temporal arteries, and began continuous intra-arterial infusion with cisplatin and a cisplatin-neutralizing agent. The bleeding stopped after the first infusion, and we continued with weekly arterial cisplatin infusion and proton beam therapy (70.4 GyE in 32 fractions). A decrease in tumor volume has been maintained for 2 years, with no evidence of new metastasis.

Polymorphous low-grade adenocarcinoma--management and reconstruction with temporalis myofacial flap

Polymorphous low-grade adenocarcinoma is a rare, malignant salivary gland tumor, which is found almost exclusively in minor salivary glands. It is more frequent in the third-seventh decade of life, with a clear female predilection in a 2:1 ratio. It is usually located in the hard or soft palate, although it may be found in the rest of the oral cavity too. It is rare in major salivary glands. In general it has good prognosis, with recurrence rates in the range of 17-24%. Although rare, metastasis to regional lymph nodes has been reported. We report a case of 38 year old female patient who reported with recurrent low grade polymorphous adenocarcinoma in the hard palate, who has been treated with wide excision of the lesion, with reconstruction of the defect using temporalis myofacial flap.

Polymorphous low grade adenocarcinoma: literature review and report of lower lip lesion with suspected lung metastasis

Polymorphous low grade adenocarcinoma (PLGA) is an uncommon tumour that affects minor salivary glands mainly. It was known to be clinically benign and histologically polymorphic; sometimes misdiagnosed as pleomorphic adenomas, monomorphic adenomas, malignant pleomorphic adenomas, adenoid cystic carcinomas and adenocarcinoma not otherwise specified. More information about PLGA is cumulating in the current literature with new evidences suggesting that the tumour may not be as indolent as it was previously thought. A thorough understanding of the clinical and histological behaviour of the lesion has serious implications in management. Here, a case of lower lip lesion with suspected lung metastasis is reported to exemplify how the clinical behaviour of the lesion may affect management.

[Polymorphous low-grade adenocarcinoma of the maxilla simulating an odontogenic cyst]

INTRODUCTION

In 1990, the WHO classified Polymorphous Low Grade Adenocarcinoma as a low-grade malignant tumor of the minor salivary glands. This tumor often originates from the hard or soft palate minor salivary glands. We report the first case revealed as an infected maxillary odontogenic cyst around an impacted tooth.

CASE REPORT

A 50-year-old female presented 20 months ago with a bulging, painful oral mass in the right superior vestibule. The diagnosis was infected odontogenic cyst associated with an impacted canine tooth. A course of oral antibiotics was given and cyst enucleation and tooth extraction were performed 6 days later. Ameloblastoma was suggested on macroscopic findings; nevertheless, the pathologic end diagnosis was Polymorphic Low-Grade Adenocarcinoma of minor salivary gland origin. After negative carcinological screening, wide surgical resection was performed. Postoperative external radiotherapy was applied to the operated area as well as to cervical lymph node areas.

DISCUSSION

Most of the 565 published cases concern a palatine location. Even though wide surgical resection is sufficient, external radiotherapy may be used on a case-by-case basis.

Update on selected salivary gland neoplasms

CONTEXT

Malignancies of the salivary gland are uncommon and account for 0.3% of all malignancies. In addition to their rarity, diagnosing these tumors can be challenging given the histologic overlap among various subtypes, their morphologic heterogeneity, and the recent recognition of new entities.

OBJECTIVE

To provide an overview of 4 salivary gland malignancies that we often see in consultation, with a focus on essential diagnostic features and the importance of reporting pertinent diagnostic information to ensure appropriate clinical management.

DATA SOURCES

Review of the literature, supplemented by the personal experience of the authors, which is based on their respective institutional experiences and consultation services.

CONCLUSIONS

When diagnosing carcinoma ex pleomorphic adenoma, pathologists must report several important pieces of information to allow for optimal clinical management. In addition to histologic subtype, the degree of differentiation as well as the degree of invasion, if any, must be reported because all have prognostic relevance. Polymorphous low-grade adenocarcinoma can be a challenging diagnosis on biopsy specimens. Evaluation of the tumor periphery and nuclear features should lead to the correct diagnosis in most cases. Salivary duct carcinoma is an aggressive malignancy characterized by histologic resemblance to breast carcinoma, high-grade cytologic features, and expression of androgen receptor. Benign and malignant myoepithelial neoplasms have a broad morphologic spectrum, and immunohistochemistry is important in reaching the correct diagnosis.

Misleading initial histological diagnosis of a polymorphous low-grade adenocarcinoma in situ ex pleomorphic adenoma-a case report

INTRODUCTION

Polymorphous low-grade adenocarcinoma (PLGA) are frequent tumours of palatinal minor salivary glands. They appear clinically as solid mass located beneath intact surface epithelium, thus quite similar with benign neoplasm. PLGA displays a low tendency of aggressive behaviour. The correct aetiology of this disorder is still unknown.

CASE REPORT

In this contribution, a PLGA is reported which was located in a pleomorphic adenoma (PA). Out of an initially incisional biopsy, only the benign part of the lesion was diagnosed. Definitive histological examination of the whole tumour revealed a small malignant fraction of the specimen besides a major part of benign tissue formations (PA).

CONCLUSION

This case shows the uncertain confidence of incisional biopsy, the variably biologic behaviour of PA, providing hints for consideration of the PLGA aetiology and highlights both the necessity to remove whole PA-like lesions as well as to perform systematically histological examination of whole specimens.

Polymorphous low-grade adenocarcinoma: a review regarding an unusual presentation as infected odontogenic cyst

The World Health Organisation (WHO) classified polymorphous low-grade adenocarcinoma (PLGA) in 1990 as a low-grade malignancy; ICD-O 8525/3 being the assigned international code. It has been frequently described as occurring in hard- or soft-palate accessory salivary glands: some cases being described in the tongue and in major salivary glands. We present an extensive literature review about PLGA and the most common diagnostic pitfalls. We also report the first case where it was seen surrounding an impacted maxillary tooth and discuss it in regard to our review.

Low-grade papillary adenocarcinoma of the palate: the significance of distinguishing it from polymorphous low-grade adenocarcinoma

Low-grade papillary adenocarcinoma (LGPA) represents a relatively rare histological variant of polymorphous low-grade adenocarcinoma (PLGA). There has been a debate as to whether LGPA is associated with greater aggressive potential compared to PLGA; this is further obfuscated by the fact that diagnostic criteria for LGPA have not been well-defined. We believe that this is the first report of a patient with LGPA who developed metastases to the femur and scalp. We review the published evidence for classifying LGPA as distinct from PLGA. The weight of published data does support the idea that LGPA is oncologically distinct from LGPA. However, as uniform diagnostic criteria are lacking, we suggest a cut-off value of 10% or greater papillary formation as being necessary to separate LGPA from PLGA.

Primary polymorphous low-grade adenocarcinoma of the bronchus: complete tumor removal with bronchoscopic resection

Primary polymorphous low-grade adenocarcinoma (PLGA) is an uncommon malignant tumor arising from the minor salivary glands, but its occurrence as a primary tumor of the tracheobronchial tree is very rare. Herein, we have reported a rare case of endobronchial PLGA in a 56-year-old woman presenting with chronic cough and progressive exertional dyspnea. Chest CT clearly demonstrated an endobronchial tumor obstructing the distal part and bifurcation of the left main bronchus and causing distal atelectasis. She underwent rigid bronchoscope with electrocautery and bronchoscopic resection of the tumor. PLGA was diagnosed histologically. Subsequent left pneumonectomy was performed and showed no evidence of residual tumor.

Relative frequency of intra-oral minor salivary gland tumors: a study of 380 cases from northern California and comparison to reports from other parts of the world

BACKGROUND

The relative frequency of individual intra-oral minor salivary gland tumors (IMSGT) is not well documented in the literature. The aim of this study was to determine the relative frequency and distribution of IMSGT in an oral pathology biopsy service and to compare the data with similar studies from different parts of the world.

METHODS

Files from the Pacific Oral and Maxillofacial Pathology Laboratory of the University of the Pacific, San Francisco, California served as a source of material for this study. Files were systematically searched for all cases of IMSGT during a 20-year period. Tumors were classified according to the 2005 WHO classification of salivary gland tumors.

RESULTS

IMSGT were identified in 380 (0.4%) cases of 92 860 accessed. This is the largest series of IMSGT from one source reported in recent years. Of the 380 tumors, 224 (59%) were benign and 156 (41%) were malignant. Of the benign tumors, pleomorphic adenoma (PA) was the most common (39.2%), followed by cystadenoma (6.3%), canalicular adenoma (6.1%), ductal papillomas (4.4%), basal cell adenoma (1.6%), and myoepithelioma (1.3%). Of the malignant tumors, mucoepidermoid carcinoma was the most common (21.8%), followed by polymorphous low-grade adenocarcinoma (7.1%), adenoid cystic carcinoma (6.3%), adenocarcinoma, not otherwise specified (NOS; 2.1%), acinic cell carcinoma (1.6%), clear cell carcinoma, NOS (1.0%), and carcinoma ex PA (0.5%).

CONCLUSIONS

Studies related to the relative frequency of individual IMSGTs from different parts of the world are difficult to compare because many studies are outdated, the number of cases is small, the list of tumors is limited, and new entities are not included. To determine the true relative frequency, more studies should be conducted, on a large number of cases from one source, by experienced pathologists in the field of salivary gland tumors.

Primary polymorphous low-grade adenocarcinoma of lung treated by sleeve bronchial resection: a case report

We report a surgical case of primary polymorphous low-grade adenocarcinoma (PLGA) of the minor salivary gland-type of the lung. A PLGA originating from the right upper lobar bronchial inlet was successfully treated by sleeve right upper lobectomy. PLGAs are thought to be indolent tumors that are preferentially localized to the palate, and they affect the minor salivary glands almost exclusively. Until now, two cases of distant metastases to the lung have been reported in the English literature. To the best of our knowledge, only one case of PLGA of minor salivary gland-type of the lung without evidence of a previous oropharyngeal primary tumor has been reported in the English literature. But the case was not a single lesion; it was bilateral tumors accompanied by tumors of the cervical lymph nodes. We report here the first case of a single primary PLGA of the minor salivary gland-type of the lung, which was successfully treated by sleeve bronchial resection of right upper lobe.

Retrospective Study and Review of Polymorphous Low-Grade Adenocarcinoma

OBJECTIVES/HYPOTHESIS

We review a single institution's experience with polymorphous low-grade adenocarcinoma. To our knowledge, this is the largest patient series of polymorphous low-grade adenocarcinoma with clinical follow-up in the otolaryngology literature.

STUDY DESIGN

We retrospectively identified 19 patients with polymorphous low-grade adenocarcinoma who had adequate clinical follow-up and pathologic specimens available for examination.

METHODS

All pathologic materials were reviewed by one head and neck pathologist.

RESULTS

The median follow-up was 9.6 years. The most frequently affected sites were the hard palate (12 patients) and soft palate (9 patients). Fifteen patients had their initial treatment at our institution, and four patients presented with a recurrent tumor. Five patients had a local recurrence after surgery; of those patients, two had initially presented with recurrent tumors. Local tumors recurred as late as 15 years after the initial surgery. One patient had regional nodal disease 20 years after the initial procedure, and another had lung metastasis. No patients received chemotherapy. The most common initial diagnoses were polymorphous low-grade adenocarcinoma, adenoid cystic carcinoma, and pleomorphic adenoma.

CONCLUSIONS

Polymorphous low-grade adenocarcinoma is an increasingly recognized malignancy that originates predominantly in the minor salivary gland. Our experience confirms good local control after a wide local excision is performed, but local recurrences can occur despite having negative margins after surgery. The delayed local recurrences and regional nodal metastases noted in our series show that prolonged follow-up is needed. This series also reports one of the first pathologically confirmed cases of distant metastasis.

Polymorphous Low-Grade Adenocarcinoma of the Parotid Gland

Polymorphous low-grade adenocarcinoma (PLGA) of the parotid gland is rare. We describe a new case in which the patient underwent parotidectomy only to experience an extensive recurrence 2 years later. The recurrence was treated with radical surgical excision and radiation therapy, and the patient remained disease-free at 5 years of follow-up. We also review the literature on primary parotid PLGA.

Polymorphous low grade adenocarcinoma presenting an uncommon radiographic aspect

The aim of this study was to present clinical, histological and immunohistochemical aspects of a polymorphous low grade adenocarcinoma occurring in the mandible. A radiolucent tumour, located in the right mandible, was removed from a 40-year-old woman. Radiographic and CT exams revealed that the lesion expanded bucco-lingual cortical plates and presented an irregular scalloping of the bone. The surrounding lining mucosa was intact. The patient underwent total surgical removal of the lesion with an intraoperative biopsy. Histological diagnosis was polymorphous low-grade adenocarcinoma confirmed by immunohistochemical study. One-year follow up was uneventful. The accurate diagnosis of lesions presenting unusual clinical aspects, as the one presented here, is critical for correctly handling treatment.

Adenoid cystic carcinoma and polymorphous low-grade adenocarcinoma of minor salivary glands: a comparative immunohistochemical study using the epithelial membrane and carcinoembryonic antibodies

OBJECTIVE

The purpose of this study was to investigate immunohistochemically the expression of epithelial membrane antigen (EMA) and carcinoembryonic antigen (CEA) in adenoid cystic carcinoma (AdCC) and polymorphous low-grade adenocarcinoma (PLGA) in an attempt to assess the ability of these markers to distinguish AdCC from PLGA when the histological features on routine hematoxylin and eosin are equivocal.

MATERIALS AND METHODS

Fourteen specimens of AdCC, 10 PLGA, and five normal minor salivary glands fixed in 10% formalin and embedded in paraffin, were retrieved from the files of our department and were retrospectively studied with the streptavidin-biotin complex method using the epithelial membrane and carcinoembryonic antibodies.

RESULTS

The immunoreactivities and the expression patterns of EMA and CEA in AdCC and PLGA were similar.

CONCLUSIONS

The results of this study suggest that the immunostaining of AdCC and PLGA with EMA and CEA could not offer an adjunctive aid in differential diagnosis between these two tumors.

Polymorphous low-grade adenocarcinoma of the palate

OBJECTIVE

Polymorphous low-grade adenocarcinoma (PLGA) is a rare tumor that mostly affects minor salivary glands. The purpose of this study is to report six new cases followed-up during a long period. We also review the literature concerning clinical, histological and immunohistochemical features, as well as the proper management.

METHODS

Malignant tumors of the salivary glands diagnosed in our department from 1990 to 1999 were reviewed. A total of 66 cases were registered. Six of these cases were diagnosed as PLGA. All cases satisfied the histopathological criteria for this entity, and at least 3 years follow-up was available.

RESULTS

In the six cases the primary location was the mucosa of the palate. Hard palate was affected in 83.3% of the cases. There were no cases of extraoral PLGA in our series. Tumors were ulcerated in a 16.6% of the cases, and exofitic in the other 86.4%. Histologically, it was observed a tumoral proliferation of round clusters of uniform cells with round-to-oval clear nuclei and small nucleoli. All the cases underwent surgical management with local excision with surgical margins, five of them with bone extirpation associated. No recurrence was observed in four cases, whereas the remaining two cases showed recurrence in the follow-up. In one of the patients, lococervical recurrence appeared 12 months after the surgery, and this patient died after a few months. The remaining patients have been followed-up for 11, 7, 4 and 3 years postoperatively, with no evidence of recurrence.

CONCLUSION

Our results for a long follow-up period support the idea for a low grade of malignancy and good prognosis of this tumor, but the appearance of recurrences many years after the surgery must induce us to be very careful and systematic with the follow-up.

Intraoral minor salivary gland neoplasms: review of 213 cases

PURPOSE

Minor salivary gland tumors (MSGTs) constitute a heterogeneous group of neoplasms with great histomorphologic variation. This study reviews a large series of benign and malignant salivary gland tumors of the oral region and determines the incidence and the correlation of the histopathologic features with the clinical characteristics.

MATERIALS AND METHODS

Two hundred thirteen cases of MSGT were retrospectively studied. Hematoxylin-eosin-stained slides were examined in all cases. Special stains and immunohistochemical stains were used in selected cases. Clinical characteristics of the neoplasms were also noted.

RESULTS

One hundred nineteen tumors were benign (56%), and 94 tumors were malignant (44%). Pleomorphic adenoma was the most common benign tumor (93 of 119). Canalicular adenoma was the second most common benign MSGT in our series (25 of 119). Of the 94 malignant MSGTs, mucoepidermoid carcinoma (MEC) (45 of 94), adenoid cystic carcinoma (22 of 94), and polymorphous low-grade adenocarcinoma (18 of 94) were the most common. Most MECs (34 of 45) were low-grade lesions. Of 5 central MECs, 3 cases occurred in the maxilla and 2 cases arose in the mandible.

CONCLUSIONS

Benign intraoral MSGTs are slightly more common than malignant MSGTs. Pleomorphic adenoma is the most common MSGT, and MEC is the most common malignant variety. The palate is the most common site for minor gland neoplasms. Benign labial salivary gland neoplasms are more common in the upper lip, and malignant labial tumors are more common in the lower lip.

Polymorphous low-grade adenocarcinoma—a rare and aggressive entity in adolescence

Polymorphous low-grade adenocarcinoma (PLGA) is an uncommon tumour that usually affects the minor salivary glands, particularly in the palate. It is rare in young patients, and here we report a case in a teenage girl. She presented at the age of 16, although the lesion had been noticed 2 years previously. The tumour showed histopathological features of PLGA, but recurred locally, behaved aggressively, and ultimately metastasised to cervical lymph nodes. This was accompanied by an altered histological picture, with a papillary cystic pattern and necrosis becoming progressively more prominent. PLGA is not always a low-grade lesion and some tumours, notably those with a papillary cystic growth pattern, may require more aggressive treatment.

Polymorphous low-grade adenocarcinoma of the major salivary glands: report of three cases in an unusual location

AIMS

Polymorphous low-grade adenocarcinoma (PLGA) is the second most common type of malignant neoplasm in minor salivary glands. Its origin in major salivary glands is considered exceedingly rare. Herein, we present three cases of de novo PLGA arising in major salivary glands.

METHODS AND RESULTS

Three cases of PLGA were identified in a large series of primary tumours of major salivary glands. We investigated their clinicopathological profiles, including immunohistochemical features. The three patients (two men and one woman) were 51, 65, and 79 years old. The tumours were 20-30 mm large; two were in the parotid gland and one in the submandibular gland. Histologically, all the tumours had a polymorphous architectural pattern showing predominantly solid, tubular, and cribriform features and invasive growth. Papillary areas were observed focally in two tumours and an 'Indian-file' array in one. The tumour cells had a bland cytological appearance and low mitotic count. Two tumours showed perineural invasion. No preexisting pleomorphic adenoma component was identified. In all cases, tumour cells were positive for epithelial markers, S100 protein, and vimentin but negative for alpha-smooth muscle actin, muscle-specific actin, and glial fibrillary acidic protein. Proliferative activities assessed with the Ki67 labelling index were 4.3%, 7.1%, and 7.6%; no p53 overexpression was observed. Two patients had local recurrence, but none had metastasis or died of tumour.

CONCLUSIONS

PLGAs arising in major salivary glands and those in minor salivary glands have similar clinicopathological and immunohistochemical characteristics. It is important to recognize that PLGA can occur ab initio in the major salivary glands, although it is extremely rare.

Polymorphous low-grade adenocarcinoma of the tonsil: report of a case and review of the literature

Polymorphous low-grade adenocarcinoma (PLGA) is a relatively common malignancy of the oral cavity, representing 7% to 11% of all intraoral minor salivary gland tumors, and 19% to 26% of those that are malignant. However, it is a rare finding in the oropharynx, with only 6 cases reported in the medical literature. The clinical features of a case of PLGA of the tonsillar fossa in a 64-year-old gentleman are presented, only the second such case reported in the medical literature. A review and discussion of the literature pertaining to PLGA of the oral cavity and the oropharynx is provided. (Am J Otolaryngol 2002;23:297-299.

Polymorphous low grade adenocarcinoma with distant metastases and deletions on chromosome 6q23-qter and 11q23-qter: a case report

Polymorphous low grade adenocarcinomas (PLGAs) are thought to be indolent tumours that are localised preferentially to the palate and affect the minor salivary glands almost exclusively. Metastases to locoregional lymph nodes occur in only 6-10% of cases. Recently, two cases of PLGA with microscopically confirmed distant metastases have been reported. This study reports a third case of PLGA with histologically and immunohistochemically confirmed distant metastases. It is the first case with multiple pleural, as well as pulmonary parenchymal, metastases and metastases in cervical and paraoesophageal lymph nodes. In most cases, PLGAs are salivary gland tumours with limited potential to metastasis and a good prognosis after local treatment. However, the recently reported cases reveal that the tumour can give rise to widely spread metastases. To obtain more information about the incidence of distant metastases, periodic chest x ray examination during follow up is desirable.

Polymorphous low-grade adenocarcinoma: a study of 40 cases with long-term follow up and an evaluation of the importance of papillary areas

Forty cases of polymorphous low-grade adenocarcinoma with a minimum of 10 years of follow up were reviewed. The patients included 13 men and 27 women age 22 to 71 years (median age, 54 years); 30 were white and 10 were black. The tumors were all intraoral, and the palate was the most common site (n = 24). Histologically, the neoplasms were characterized by nonencapsulated, infiltrative borders: bland, regular nuclei; and highly variable growth patterns, including tubular, solid, papillary, microcystic, cribriform (with true lumens), pseudoadenoid cystic (without true lumens), fascicular, single file, and strand-like. Papillary areas of more than focal extent were present in 17 cases, but these cases were otherwise similar to the remainder and were considered to form part of the spectrum of polymorphous low-grade adenocarcinoma. Thirteen patients had local recurrence, which was not controlled by subsequent treatment in six; six patients had cervical lymph node metastasis; three patients had distant metastasis; and five patients died of or with tumor after prolonged periods. There was a statistically significant relationship between more than focal papillary growth and cervical lymph node metastasis, and between positive or unknown surgical margins and local recurrence (although not uncontrolled local recurrence); however, these were the only independent statistically significant correlations found between any clinical or pathologic parameter and any aspect of tumor behavior or patient survival.

The surgical pathology of salivary gland neoplasms

The accurate and precise classification of salivary gland tumors is imperative. The various types of salivary gland tumors are distinct in their clinical behavior and response to treatment, and the surgical pathology diagnosis weighs heavily on therapeutic decisions and patient prognosis. The surgical pathology of salivary gland tumors is indeed challenging, but it need not be overwhelming. This review emphasizes those morphologic patterns and cellular features that are most helpful in accurately classifying the primary epithelial neoplasms most commonly encountered in the major and minor salivary glands.

Cytologic diagnosis of adenoid cystic carcinoma of salivary glands

The cytomorphologic features in fine-needle aspiration (FNA) biopsies from 31 primary and 33 recurrent adenoid cystic carcinomas (ACC) were investigated. The correct FNA diagnosis was established in 24 of 31 primary ACC (77%). The diagnostic clue in aspirates from ACC are large globules of extracellular matrix, partially surrounded by basaloid tumor cells. In FNAs with predominance of basaloid tumor cells, but lacking characteristic globules, all other benign and malignant salivary gland tumors of epithelial-myoepithelial differentiation should be considered in the cytologic diagnosis. Pleomorphic adenoma is most frequently confused with ACC, and therefore, the cytologic findings in FNAs from 50 pleomorphic adenomas were compared with those diagnosed as ACC. Furthermore, rare neoplasms of salivary glands with epithelial-myoepithelial cell differentiation, including basal-cell adenoma and carcinoma, epithelial-myoepithelial carcinoma, and polymorphous low-grade adenocarcinoma, as well as some nonsalivary gland neoplasms presenting an adenoid cystic pattern, must be considered. The cytologic features of these entities are discussed in detail with respect to the cytologic diagnostic criteria of ACC.

Fine-needle aspiration cytology of polymorphous low-grade adenocarcinoma of the tongue

The cytologic features derived from a fine-needle aspiration of polymorphous low-grade adenocarcinoma (PLGA) of the base of the tongue are described. The tumor cells were composed of cuboidal epithelial cells and short, spindle-shaped myoepithelial-like cells, and they formed large cell clusters. In the central portion of the clusters, myxoid materials were present, and palisading tumor cells occasionally surrounded them. Histological examination revealed solid proliferation of the epithelial cuboidal and spindle cells. The former frequently formed tubular and papillary structures. The tumor was not encapsulated, and invasion of adjacent muscle tissue was noted. Although the cytologic differentiation from cellular variants of pleomorphic adenoma and myoepithelioma is difficult, the feature of palisading tumor cells may be useful in the differential diagnosis.