Application of α-smooth muscle actin and c-kit in the differential diagnosis of adenoid cystic carcinoma from polymorphous low-grade adenocarcinoma

Immunohistochemical Profile of Polymorphous Adenocarcinoma of Minor Salivary Gland: A Systematic Review and Meta-Analysis

Polymorphous adenocarcinoma (PAC) is a rare variant of minor salivary gland tumors. Because of its architectural diversity, histological diagnosis of PAC can be difficult especially for small biopsies, and immunohistochemistry is of great help in differentiating it from its histologic mimics. The aim of this study is to conduct a systematic literature review to identify reliable immunohistochemical markers for PAC. We conducted an electronic literature search of the MEDLINE, ScienceDirect, SpringerLink, and Wiley Online Library databases, covering the literature published in the period between 1988 and 2021. The eligibility criteria included case reports and retrospective studies of PAC cases with details of immunohistochemical markers. Following the search and selection process, 32 studies with 409 cases were included in this systematic review. Overall, > 90% positivity was observed for pan-cytokeratin (CK) (97.3%), CK7 (96.8%), CK7/8 (97.4%), E-cadherin (90.0%), Vimentin (92.5%), S100 (97.0%), p63 (91.7%), and SOX10 (100%), while little to no positivity was observed for CK20 (0.0%), p40 (0.0%), and GFAP (5.0%). The average MIB-1 labeling index was 3.78%. The results of this systematic review indicate that CK7+/CK20-, p63+/p40-, S100+, Vimentin+, and GFAP- immunophenotype have diagnostic value for PAC. In addition, the use of S100, MSA, p40, and c-Kit provide additional layers of information helpful to differentiate PAC from adenoid cystic carcinoma, one of challenging differential diagnoses.

Microsecretory Adenocarcinoma of Salivary Glands: An Expanded Series of 24 Cases

Microsecretory adenocarcinoma (MSA) is a recently described salivary gland tumor with a characteristic histologic and immunophenotypic profile and recurrent MEF2C-SS18 fusions. Because only six cases of MSA have been published, its complete clinicopathologic spectrum is unclear, and its biologic behavior has not been documented. Here, we present an updated and expanded experience of 24 MSA cases. All cases of MSA were obtained from the authors' files. Immunohistochemistry for S100, SOX10, p63, p40, SMA, calponin, and mammaglobin was performed. Molecular analysis was performed by targeted RNA sequencing, SS18 break apart fluorescence in situ hybridization, and/or reverse transcriptase polymerase chain reaction for MEF2C-SS18 fusion. Clinical follow-up was obtained from medical records. A total of 24 MSA cases were collected, from 13 women and 11 men, ranging from 17 to 83 years (mean 49.5 years). The vast majority (23 of 24) arose in the oral cavity, with the palate (n = 14) and buccal mucosa (n = 6) as the most frequent subsites. Tumors showed consistent histologic features including: (1) microcystic tubules, (2) flattened intercalated duct-like cells, (3) monotonous oval hyperchromatic nuclei, (4) abundant basophilic luminal secretions, (5) fibromyxoid stroma, and (6) circumscribed borders with subtle infiltration. The tumors were very consistently positive for S100 (24 of 24), p63 (24 of 24), and SOX10 (14 of 14) and negative for p40 (0 of 21), calponin (0 of 12) and mammaglobin (0 of 16), while SMA (4 of 20) was variable. MEF2C-SS18 fusion was demonstrated in 21 of 24 cases; in the remaining 3 cases with insufficient RNA, SS18 break apart FISH was positive. Treatment information was available in 17 cases, all of which were managed with surgery only. In 14 cases with follow-up (1-216 months, mean 30), no cases recurred or metastasized. MSA is a distinct salivary gland neoplasm with remarkably consistent clinical, histologic, immunophenotypic, and genetic features that generally behaves in an indolent manner following surgery alone. These observations solidify MSA as a unique, low-grade salivary gland carcinoma that warrants inclusion in the next version of the WHO classification of head and neck tumors.

Utility of p63 and p40 in Distinguishing Polymorphous Adenocarcinoma and Adenoid Cystic Carcinoma

Objective:

Adenoid cystic carcinoma and polymorphous adenocarcinoma are primarily the tumor of minor salivary glands. Both show certain morphological similarities, which limit their proper diagnosis in settings where there are obscuring factors and limited biopsy material. However, there is a considerable difference in treatment and prognosis, which raises the need to distinguish these two entities. In this study, we discuss the utility of two immunohistochemical stains, p63 and p40, in different combinations for distinguishing polymorphous adenocarcinoma from adenoid cystic carcinoma.

Materials and Methods:

Two immunohistochemical stains, p63 and p40, were performed on 47 cases of adenoid cystic carcinoma and 23 cases of polymorphous adenocarcinoma.

Results:

36 out of 47 cases of adenoid cystic carcinoma showed p63+ve/p40+ve immunoprofile, followed by p63-ve/p40-ve immunoprofile, which is seen in10 cases of adenoid cystic carcinoma. However, 22 out of 23 cases of polymorphous adenocarcinoma displayed p63+ve/p40-ve immunoprofile. p63-ve/p40+ve is the least frequent observed immunoprofile, which is seen in only one case of adenoid cystic carcinoma.

Conclusion:

On combining all possible immunoprofile combinations, p63+ve/p40-ve immunoprofile appears to be the most sensitive profile for distinguishing polymorphous adenocarcinoma from adenoid cystic carcinoma.

Utility of smooth muscle actin and CD117 as reliable markers in the diagnosis of salivary gland neoplasms

Objective:

The aim of this study is to analyze the utility of immunohistochemical markers such as CD117 and smooth muscle actin (SMA) in the diagnosis of various benign and malignant salivary gland neoplasms.

Materials and Methods:

The study comprises 17 samples categorized into three groups: Group I consisted of 5 histopathologically normal salivary gland tissue; Group II comprised 7 cases, of which 3 cases were pleomorphic adenoma, 3 cases were myoepithelioma and 1 case was Warthin's tumor; and Group III consisted of 5 cases, of which 1 was mucoepidermoid carcinoma and 4 cases were adenoid cystic carcinoma. The selected cases were subjected to immunohistochemistry (IHC) procedure to assess the expression pattern of CD117 and SMA.

Results:

In SMA, 85.8% showed severe-to-moderate intense expression among the tumor cells in benign salivary gland tumor. All the 5 malignant tumors showed the expression of SMA and 3 cases demonstrated severe expression among the tumor cells. An intense expression pattern of SMA was observed in both benign and malignant neoplasms in the periphery and stromal components of the tumor. Only two cases were positive for CD117, and connective tissue components were completely negative in both malignant and benign salivary gland neoplasms.

Conclusion:

Alpha-SMA can be utilized as reliable IHC markers for salivary gland neoplasms due to its diagnostic importance in tumors with myoepithelial origin indicative of the histogenesis of salivary gland tumors.

Diagnostic utility of C-kit protein (CD117) expression in differentiating adenoid cystic carcinoma and polymorphous low grade Adenocarcinoma

Background & Objective:

To evaluate usefulness of immunohistochemical marker C-kit (CD117) in differentiating Adenoid cystic carcinoma (AdCC) from Polymorphous low-grade adenocarcinoma (PLGA) in patients of salivary gland carcinomas. AdCC is a malignant salivary gland neoplasm with poor prognosis. PLGA is a salivary gland malignancy with indolent growth pattern. Differentiating between the two entities is a diagnostic challenge. We evaluated the role of C-kit in differentiating the two.

Methods:

This is a Cross sectional study. Samples of 19 tumors including 12 AdCC and 4 PLGA was evaluated at Department of Histopathology, Armed Forces Institute of Pathology, Rawalpindi from December 2015 to August 2016. Immunohistochemical techniques were used to analyze the level of c-kit expression in AdCC (n = 12), polymorphous low-grade adenocarcinoma (PLGA) (n = 6). Samples were stained using monoclonal antibody against C-kit. Statistical analysis of the data was done using SPSS version 21.

Results:

Strong diffuse cytoplasmic reactivity was observed in more than 50% of the tumor cells of AdCC whereas less than 20% of cells showed negative to weak positivity in PLGA. Hence, the difference in the expression of c-kit between AdCC and PLGA was statistically significant (p value <0.002).

Conclusions:

CD117 expression itself can be used as a marker in differential diagnosis of salivary gland neoplasms. However, the percentage of the CD117 immunoreactive cells and the staining intensities appeared to be important factors in distinguishing AdCC from PLGA.

Diagnosis and Management of Malignant Salivary Gland Tumors of the Parotid Gland

Malignant parotid tumors are heterogeneous and diverse. Accurate diagnosis requires a pathologist familiar with the various histologic subtypes, immunohistochemistry stains, and common translocations. Clinical course varies according to tumor subtype, ranging from indolent, slow-growing adenoid cystic carcinoma to rapidly progressive, possibly fatal, salivary ductal carcinoma. Histologic grade is important in prognosis and therapy. Surgery remains the mainstay of treatment when negative margins can be achieved. Radiation improves locoregional control of tumors with high-risk features. Chemotherapy for parotid tumors can be disappointing. Studies of new targeted therapies have not offered significant benefits.

Polymorphous low-grade adenocarcinoma of the epiglottis: A case report

Polymorphous low-grade adenocarcinoma is an uncommon malignant tumor derived from the terminal duct cells of the salivary glands. The present study described a rare case of polymorphous low-grade adenocarcinoma, T2N0M0 stage 2, in a 65-year-old man, who presented with a sore throat and painful dysphagia. Computed tomography revealed an infiltrative heterogenous enhancing mass involving the left aryepiglottic fold. He underwent a tumor removal with frozen section for evaluating the surgical margin. Subsequent supraglottic laryngectomy was performed. Polymorphous low-grade adenocarcinoma was diagnosed histologically, characterized by cytologic uniformly, morphologic diversity and an infiltrative growth pattern. Epiglottic cartilaginous invasion by the tumor is demonstrated. Clinical, radiological, endoscopic and pathological features with briefly reviewed relevant literatures are discussed. This is the first reported description in the literature, to the best of our knowledge, of an epiglottic polymorphous low-grade adenocarcinoma receiving successful supraglottic laryngectomy with 7 year disease free survival.

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.

Polymorphous low grade adenocarcinoma has a consistent p63+/p40- immunophenotype that helps distinguish it from adenoid cystic carcinoma and cellular pleomorphic adenoma

Polymorphous low grade adenocarcinoma (PLGA) is a tumor of minor salivary glands that exhibits considerable morphologic overlap with adenoid cystic carcinoma and cellular pleomorphic adenoma, especially in small biopsy specimens. Unlike these other tumor types. PLGAs do not harbor a myoepithelial component, yet their frequent positivity for p63 diminishes the usefulness of this particular myoepithelial marker as a discriminating immunostain. p40 is an antibody that recognizes ΔNp63, a p63 isoform that is more specific for true myoepithelial differentiation. As such, p40 immunostaining could help distinguish PLGAs from adenoid cystic carcinomas and pleomorphic adenomas. In this study, p63 and p40 immunohistochemistry was performed on paraffin embedded, formalin fixed tissue from 11 PLGAs, 101 adenoid cystic carcinomas, and 31 pleomorphic adenomas. All 11 PLGAs (100 %) were positive for p63 but completely negative for p40. Among adenoid cystic carcinomas, 91 of 101 (90 %) were positive for p63 and 90/101 (89 %) were positive for p40. The single discordant p63+/p40- adenoid cystic carcinoma exhibited solid architecture and high grade features not typically seen in PLGA. Among pleomorphic adenomas, 21/31 (68 %) were positive for p63 and 13/31 (42 %) were positive for p40. For the pleomorphic adenomas, the discordant p63+/p40- staining pattern was seen only in the overtly mesenchymal chondromyxoid stroma. The cellular epithelial component of the pleomorphic adenomas demonstrated concordant p63+/p40+ or p63-/p40- immunophenotypes. PLGA consistently exhibits a p63+/p40- immunophenotype that can help distinguish it from adenoid cystic carcinoma and cellular pleomorphic adenoma, tumors that characteristically demonstrate concordant p63 and p40 immunostaining patterns. A p63/p40 immunohistochemical panel can provide a valuable tool for making the distinction between these morphologically similar but clinically divergent entities.

Evaluation of c-kit protein (CD117) expression in common salivary gland neoplasms

BACKGROUND

Adenoid cystic carcinoma (AdCC) is a malignant salivary gland neoplasm with poor long-term prognosis. Differentiating between AdCC and other salivary gland neoplasms can be a diagnostic challenge, particularly in examining tissues obtained from small incisional biopsies.

AIM

The aim of this study was to evaluate c-kit expression in four common benign and malignant salivary gland neoplasms.

MATERIALS AND METHODS

Immunohistochemical techniques were used to analyze the level of c-kit expression in normal salivary gland (n = 10) and four different types of salivary gland tumors: Pleomorphic adenoma (PA) (n = 17), AdCC (n = 9), polymorphous low-grade adenocarcinoma (PLGA) (n = 4) and mucoepidermoid carcinoma (MEC) (n = 6). Samples were immunostained using monoclonal antibody against c-kit.

RESULTS

The immunoreactivity for c-kit was found in all cases of AdCC, PLGA and MEC and majority of PAs. Positive reactivity was observed in more than 50% of the tumor cells of AdCC and less than 50% in PLGA. PA did not show strong immunostaining and c-kit was predominantly localized to the cell membrane. Furthermore, the difference in the expression of c-kit between the benign and malignant neoplasms was not statistically significant.

CONCLUSIONS

CD117 expression itself cannot be used as a marker in differential diagnosis of salivary gland neoplasms. However, the percentage of the CD117 immunoreactive cells and the staining intensities appeared to be important factors in distinguishing AdCC from PLGA and PA.

Immunohistochemical clue for the histological overlap of salivary adenoid cystic carcinoma and polymorphous low-grade adenocarcinoma

It remains difficult to distinguish adenoid cystic carcinoma (ACC) from polymorphous low-grade adenocarcinoma (PLGA). Although these neoplasms exhibit nearly similar histologic patterns, their biologic behavior is significantly different. This study was carried out in an attempt to overcome the histological overlap between these tumors using immunohistochemical method for c-kit and galectin-3 proteins on twenty cases of salivary gland tumors including twelve ACC and eight PLGA. Results revealed positive cytoplasmic reactivity for c-kit in 100% of ACC cases and only in 25% of PLGA. On the other hand, galectin-3 expression was observed in 100% of both ACC and PLGA cases. Moreover, solid variant of ACC showed overexpression of both proteins than cribriform and tubular subtypes. Significant positive correlation between the two studied proteins in ACC and PLGA was also observed (p < 0.05). Upon these results, over expression of c-kit and galectin-3 in ACC cases supports the concept of solid variant as a high-grade tumor. Moreover, c-kit may be used as a helpful marker to distinguish ACC from PLGA in cases where the diagnosis can be challenging.

Polymorphous low-grade adenocarcinoma: an analysis of epidemiological studies and hints for pathologists

Background

This study is an analysis of the prevalence of polymorphous low grade adenocarcinoma (PLGA) in epidemiological surveys of salivary tumors published in the English language from 1992 to 2012.

Methods

These surveys included studies from different researchers, countries and continents. The 57 surveys for which it was possible to calculate the percentage of PLGAs among all malignant minor salivary gland tumors (MMSGT) were included in this review.

Results

The statistical analyses show significant differences in the PLGA percentage by time period, country and continent in the studies included in this review. The percentage of PLGAs among MMSGTs varied among the studies, ranging from 0.0% to 46.8%. PLGA rates have varied over the period studied and have most recently increased. The frequency of reported PLGA cases also varied from 0.0% to 24.8% by the country in which the MMSGT studies were performed. The PLGA percentages also varied significantly by continent, with frequencies ranging from 3.9% in Asia to 20.0% in Oceania

Conclusion

Based on these results, we concluded that although the accuracy of PLGA diagnoses has improved, they remain a challenge for pathologists. To facilitate PLGA diagnoses, we have therefore made some suggestions for pathologists regarding tumors composed of single-layer strands of cells that form all of the histological patterns present in the tumor, consistency of the cytological appearance and uniformly positive CK7, vimentin and S100 immunohistochemistry, which indicate a single PLGA phenotype.

Virtual slide

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1059098656858324

Myofibroma of the oral mucosa: a case report

OBJECTIVE

To report a case of coexisting irritation fibroma and myofibroma in oral mucosa.

CLINICAL PRESENTATION AND INTERVENTION

One case with two painless, nodular masses, adjacent to each other in the buccal mucosa, was clinically examined with a provisional diagnosis of irritation fibroma, salivary gland tumors, neurofibroma and schwannoma. Histological examination of the smaller swelling showed features of irritation fibroma, while the features of the other mass were compatible with myofibroma or leiomyoma. Additional immunohistochemical examination established the diagnosis of myofibroma.

CONCLUSION

This was a case of a myofibroma that was clinically similar to an adjacent irritation fibroma, which highlights the possibility of misdiagnosis of a myofibroblastic tumor and underlines the importance of histologic examination together with immunohistochemical and/or histochemical analysis if necessary to establish the accurate diagnosis.

Expression of c-kit and Slug correlates with invasion and metastasis of salivary adenoid cystic carcinoma

The overexpression of c-kit seems to be frequent and specific in salivary adenoid cystic carcinoma (ACC), however, there is little information on correlation between c-kit expression and the invasion and metastasis. Recently, the data showed that Slug, a transcription factor of epithelial-mesenchymal transitions (EMT), is a molecular target that contributes to the biological specificity of c-kit signaling pathway. In this study, the expression of c-kit and Slug was evaluated in two ACC cell lines and 121 patients with ACC. The results of real-time RT-PCR and Western blot showed that ACC-2 and ACC-M cell lines expressed c-kit and Slug mRNA and protein. The immunohistochemical assay in patients demonstrated that positive expression of c-kit and Slug was observed in 108/121 (89.26%) and 87/121 (71.90%) of cases, respectively, and that c-kit and Slug expression was significantly associated with tumor site, TNM stage, histological pattern, perineural invasion, local regional recurrence and distant metastasis of patients with ACC (P<0.05). Furthermore, there was a significant association between the positive expression of c-kit and that of Slug (P=0.046). These findings indicated that c-kit/Slug pathway might participate in the invasion and metastasis of salivary ACC.

Immunohistochemical expression of vimentin, calponin and HHF-35 in salivary gland tumors

Myoepithelial cells present a complex immunophenotype, with the expression of proteins varying according to the stage of normal or neoplastic differentiation of the cell. In order to evaluate the immunohistochemical markers expressed by these cells, a panel of antibodies composed of vimentin, calponin and HHF-35 was applied to 28 salivary gland tumors. The results demonstrated a higher percent sensitivity of vimentin and calponin compared to HHF-35. However, calponin and HHF-35 presented a focal labeling pattern in contrast with the diffuse distribution of vimentin. The cells predominantly stained by all tested antibodies included nonluminal cells in duct-like and tubular structures, such as those seen in pleomorphic adenomas and adenoid cystic carcinomas, as well as cells in the cords and nests of polymorphous low-grade adenocarcinomas and peripheral cells of sheets and nests of myoepitheliomas. In conclusion, the combination of calponin and vimentin is suggested for the identification of myoepithelial cells in salivary gland tumors.