Lacrimal Gland Pleomorphic Adenoma and Carcinoma ex Pleomorphic Adenoma

Insights into the molecular alterations of PLAG1 and HMGA2 associated with malignant phenotype acquisition in pleomorphic adenoma

Pleomorphic adenoma (PA) is the most common neoplasm of the salivary gland, presenting with a variety of histological features. In some cases, PA can undergo malignant transformation to carcinoma ex pleomorphic adenoma (CXPA). The transition from PA to CXPA is associated with complex molecular alterations, particularly involving the pleomorphic adenoma gene 1 (PLAG1) and high mobility group protein gene (HMGA2). This review investigates the molecular alterations of PLAG1 and HMGA2 in all domains in the malignant transformation of PA. Our analysis highlights that these markers are key alterations in the etiopathogenesis of PA and CXPA, with gene fusion and amplification being frequently reported mechanisms. Although the exact role of PLAG1 and HMGA2 in the oncogenic process remains unclear, further studies on the HMGA2 and PLAG1, are needed particularly in HMGA2-PLAG1-IGF2 which is proving to be a potential pathway for the development of clinically applicable therapies, especially for CXPA management.

Malignant Salivary Gland Neoplasm of the Tongue Base with EWSR1::BEND2 Fusion: An Unusual Case with Literature Review

PURPOSE

Salivary gland malignancies may have overlapping architectural patterns, tumor morphology, and immunohistochemical phenotypes, presenting challenges in precise classification. Molecular phenotyping has become quite useful for providing an additional diagnostic modality, and potential drug targets. Here we reported a young female patient with salivary gland tumor of the tongue base harboring genetic alterations by next generation sequencing (NGS).

METHODS

The morphological, immunohistochemical and molecular features of this case were described, and related literature was reviewed.

RESULTS

The tumor showed an epithelial myoepithelial architecture arranged in cords and tubules interwoven with a chondromyxoid stroma, along with perineural invasion and adjacent striated muscle infiltration. Myoepithelial cells were positive for CK5/6, partially positive for P63 and CK7, and sporadically positive for S100. Immunoprofiling revealed a low density of infiltrating lymphocytes and macrophages and the absence of programmed death ligand 1 (PD-L1). Notably, RNA-based NGS showed EWSR1::BEND2 gene fusion in this tumor, and EWSR1 break-apart was confirmed by fluorescence in situ hybridization. This led to a final diagnosis of a minor salivary gland malignancy with EWSR1::BEND2 fusion. Only two other cases of salivary gland tumors with EWSR1::BEND2 fusion had been previously reported, which were also detected via RNA-based NGS.

CONCLUSION

This study emphasized that EWSR1::BEND2 fusion may drive the carcinogenesis in salivary glands neoplasia. In clinic RNA-based NGS could be essential for precise genotyping of EWSR1 fusion in this rare disease.

[Interdisciplinary Management of Orbital Diseases]

Diagnosis and therapy of orbital diseases is an interdisciplinary challenge, in which i.e. otorhinolaryngologists, ophthalmologists, radiologists, radiation therapists, maxillo-facial surgeons, endocrinologists, and pediatricians are involved. This review article describes frequent diseases which both, otolaryngologists and ophthalmologists are concerned with in interdisciplinary settings. In particular the inflammatory diseases of the orbit including orbital complications, autoimmunological diseases of the orbit including Grave´s orbitopathy, and primary and secondary tumors of the orbit are discussed. Beside describing the clinical characteristics and diagnostic steps the article focusses on the interdisciplinary therapy. The review is completed by the presentation of most important surgical approaches to the orbit, their indications and possible complications. The authors tried to highlight the relevant facts despite the shortness of the text.

Recurrence rate of pleomorphic adenoma of the lacrimal gland: systematic review and meta-analysis

PURPOSE

The aim is to increase the understanding of lacrimal gland pleomorphic adenoma's recurrence rate and the factors that influence it.

METHODS

A systematic search of PubMed, SCOPUS, Cochrane Library, and CINAHL was conducted following PRISMA guidelines. The data in the included studies were extracted and analyzed.

RESULTS

Twenty-two studies were included representing 963 patients from 12 different countries. The pooled analysis of the recurrence rate was 8.83% (95% CI: 5.08-13.50). In the event of recurrence, there was a 75.17% (95% CI: 65.98-82.94) chance of benign recurrence and a 28.35% (95% CI: 19.66-38.41) chance of malignant recurrences, with malignant recurrence occurring almost exclusively after a benign recurrence. The results showed that 47.09% (95% CI: 24.60 to 70.22) of recurrent tumors had a ruptured pseudocapsule and 6.35% (95% CI: 0.82 to 16.54) had an intact pseudocapsule with a significant difference between the two. Of the recurrent tumors, 51.50% (95% CI: 9.28 to 92.39) were biopsied compared to 8.83% (95% CI: 3.40 to 16.49) of the total; the difference between these two proportions was also found to be significant.

CONCLUSION

There was a statistically significant difference in the rates of recurrence between tumors that were either biopsied or had a ruptured pseudocapsule compared to those that did not. This evidence adds additional support for excisional biopsy being the procedure of choice for LGPA and reinforces the importance of keeping the pseudocapsule intact during surgical resection.

Recurrent lacrimal gland pleomorphic adenoma

Pleomorphic adenoma is the most common tumour of the lacrimal gland. Correct preoperative diagnosis is essential as the tumour should be removed en bloc. Incisional biopsy is contraindicated due to risk of recurrence and subsequent risk of malignancy. We identified 13 patients who were diagnosed with lacrimal gland pleomorphic adenoma in our institution over a 31-year period from 1990 to 2021. Of these, we describe four patients, three males and one female, who underwent incisional biopsy. One of these patients had a number of recurrences and required an orbital exenteration. The other two were treated with radiation to the orbit and experienced severe dry eye post-radiotherapy. All three patients are currently disease-free. The fourth patient underwent an incisional biopsy of his lacrimal gland pleomorphic adenoma (LGPA) within the last 6 months and has been referred for radiotherapy. The reasons for a lack of preoperative diagnosis of LGPA included clinical uncertainty and broad radiologic differential. None of the patients who had an en bloc resection experienced recurrence. We recommend that a fine needle aspirate (FNA) biopsy in lieu of a tissue biopsy should be performed where LGPA is included in the clinical and radiological differential diagnosis. If incisional biopsy is required, the suture track should be marked so that the entire biopsy track is removed with the specimen.

A rare case of mucoepidermoid carcinoma ex pleomorphic adenoma of the lacrimal gland

Carcinoma ex pleomorphic adenoma (CEPA) of the lacrimal gland is a rare malignant tumor that arises from a pre-existing pleomorphic adenoma. Lacrimal gland CEPA with mucoepidermoid histological subtype is exceedingly rare. Diagnosis can be aided by radiographic findings, though the gold standard is histopathological analysis following excisional biopsy. Management options include complete surgical excision with or without adjuvant radiation therapy based on tumor grade and invasiveness. We present a 76-year-old woman with 6 months of diplopia and unilateral proptosis. Her initial exam was remarkable for hypoglobus, proptosis, and limited elevation of the right eye. Computed tomography (CT) scan demonstrated a superior, well-circumscribed, extraconal orbital mass. An excisional biopsy was performed, and histopathological findings were consistent with mucoepidermoid carcinoma ex pleomorphic adenoma with positive margins in the tumor capsule. The patient received radiation therapy and remains markedly improved with no disease recurrence at 5 months post-operatively.

Carcinoma Ex Pleomorphic Adenomas: An Institutional Experience and Literature Review

OBJECTIVES

To provide an institutional experience with cases diagnosed as carcinoma ex pleomorphic adenoma (CXPA), including the cytologic and histologic findings and clinical follow-up, followed by a comparison to the experience documented in the literature.

METHODS

We identified cases of CXPA diagnosed at our institution from 2011 to 2021 and reviewed the cytologic and histologic diagnoses, as well as the treatment and clinical outcomes. Additionally, a literature review of the English literature was performed on CXPAs from 2011 to 2021.

RESULTS

Forty-one cases of CXPA were identified, with the majority subclassified as adenocarcinoma, not otherwise specified. Five tumors underwent cytogenetic studies and five underwent molecular studies. To date, 36 patients are alive, 8 of whom experienced locoregional recurrence or distant metastasis.

CONCLUSIONS

Our institutional experience was comparable to that reported in the literature. Further studies are required to inquire about the role of molecular profiles of CXPAs in clinical risk assessment.

Risk and Lag-time for Development of Lacrimal Gland Carcinoma Expleomorphic Adenoma: Observations and Conjectural Study

AIMS

To estimate the proportion of de novo lacrimal gland pleomorphic adenomas (PAs) and carcinomas expleomorphic adenomas (CEPAs), together with age at presentation and first symptom. Conjectural models of tumor growth are considered.

METHODS

Retrospective review of patients with orbital lobe PA or CEPA. The presenting age was examined for conformation to a Gaussian distribution and the cumulative distribution function derived for both tumor types. The risk of CEPA with age was estimated by logistic regression.

RESULTS

About one-sixth (27/172; 16%) of these primary orbital lobe tumors were CEPAs, with 145 PAs (76/145 male; 52%) and 27 CEPAs (12/27 male; 44%). The mean presenting age for PAs was 48.3 years (median 47.7; range 11-84 years) and 57.7 years for CEPAs (median 61.2, range 27-91 years) ( p = 0.0062), and the standard deviations for each group are almost identical (16.3 for PAs, 15.9 for CEPAs; p = 0.92). Five (3.4%) PAs and 1 (3.7%) CEPA were asymptomatic: otherwise, the median symptom duration was 24 months for both PAs and CEPAs ( U test: p = 0.65). The odds of CEPA rises significantly with age, increasing 1.04-fold annually ( p = 0.0079).

CONCLUSION

The almost identical measures of dispersion for the presenting ages of PA and CEPA suggests that, once malignant transformation occurs, there might be a relatively constant period before it is evident. CEPAs present about a decade after PAs, this unexpectedly later presentation for the malignancy possibly being explained by a gradual replacement of the PA by the newly arising carcinoma within the preceding benign tumor.

Chromosome Translocations, Gene Fusions, and Their Molecular Consequences in Pleomorphic Salivary Gland Adenomas

Salivary gland tumors are a heterogeneous group of tumors originating from the major and minor salivary glands. The pleomorphic adenoma (PA), which is the most common subtype, is a benign lesion showing a remarkable morphologic diversity and that, upon recurrence or malignant transformation, can cause significant clinical problems. Cytogenetic studies of >500 PAs have revealed a complex and recurrent pattern of chromosome rearrangements. In this review, we discuss the specificity and frequency of these rearrangements and their molecular/clinical consequences. The genomic hallmark of PA is translocations with breakpoints in 8q12 and 12q13-15 resulting in gene fusions involving the transcription factor genes PLAG1 and HMGA2. Until recently, the association between these two oncogenic drivers was obscure. Studies of the Silver−Russel syndrome, a growth retardation condition infrequently caused by mutations in IGF2/HMGA2/PLAG1, have provided new clues to the understanding of the molecular pathogenesis of PA. These studies have demonstrated that HMGA2 is an upstream regulator of PLAG1 and that HMGA2 regulates the expression of IGF2 via PLAG1. This provides a novel explanation for the 8q12/12q13-15 aberrations in PA and identifies IGF2 as a major oncogenic driver and therapeutic target in PA. These studies have important diagnostic and therapeutic implications for patients with PA.

Expression of cartilage oligomeric matrix protein (COMP) associates with capsular invasion in salivary gland pleomorphic adenoma

BACKGROUND

Accumulating evidence shows that pleomorphic adenoma (PA) exhibits a unique capsular invasion and with a crucial role in recurrence. This study was designed to explore RNA expression profiles in salivary gland PA in an attempt to further analyse genes associate with capsule invasion.

METHODS

We evaluated the expression profiles of 4 salivary gland PA patients by RNA-sequencing. The principal functions of the differentially expressed mRNAs (DEGs) were explored using GO and KEGG analysis. Then, RT-qPCR and correlation analyses were performed to verify the candidate DEGs in 59 PA patients, and immunohistochemical examinations were conducted to validate candidate DEGs. Finally, the COMP-related genes were screened using correlation and biological pathway enrichment analysis, and further validated by RT-qPCR.

RESULTS

A total of 974 DEGs were significantly upregulated and 1464 were downregulated (fold change ≥2.0; p < 0.05). Based on GO and KEGG analyses, extracellular matrix organization and the PI3K-Akt signaling pathway might play pivotal roles in the tumorigenesis of PA. 40 DEGs were screened and validated by RT-qPCR, 11 upregulated and 5 downregulated DEGs were consistent with the sequencing results. Cartilage oligomeric matrix protein (COMP) was identified to have a significant correlation with the capsular invasion of PA and expression of COMP in patients with invasive capsular PA was significantly stronger than PA. Finally, further results could reveal that 5 highest-scoring genes were screened as hub genes for COMP.

CONCLUSIONS

These findings suggested that COMP may be a prognostic target for PA and might contribute to its capsular invasion.

Proptosis Revealing a Rare Lacrimal Gland Tumor: A Case of Chondroid Syringoma in a 35-year-old Patient

Lacrimal gland chondroid syringoma is a very rare tumor with classic clinico-radiological symptoms that should be familiar to clinicians for appropriate patients’ management as the tumor has potential for recurrence and malignant transformation. We report herein a case of chondroid syringoma in a 35-year-old patient presenting with progressive painless proptosis for 2 years. He underwent complete surgical removal of the tumor, with subsequent clinical improvement of his symptoms.

Metabolic alterations in carcinoma ex pleomorphic adenoma development of lacrimal glands

PURPOSE

To evaluate metabolic alterations along with the carcinoma ex pleomorphic adneoma (CXPA) development of lacrimal glands (LG).

METHODS

Four samples of the normal LG (NLG), 9 of pleomorphic adenoma (PA), 4 of residual PA (rPA), and 4 of CXPA of LG were included. GLUT-1, HIF-1α, FASN, and adipophilin by immunohistochemical stains were performed in the selected cases.

RESULTS

Was observed higher expression of markers associated with glycolytic and lipid metabolism in the tumor tissue samples when compared to the NLG samples. Additionally, GLUT-1, FASN, and Adipophilin were more expressed in CXPA samples while HIF-1α in PA samples.

CONCLUSIONS

In conclusion, our results demonstrate overexpression of FASN and Adipophilin in CXPA which may reflect a metabolic shift toward lipogenesis in cancer cells.

Masses of the Lacrimal Gland: Evaluation and Treatment

Lacrimal gland lesions account for approximately 9 to 10% of all biopsied orbital masses. Potential causes include nongranulomatous and granulomatous inflammation, autoimmune disease, lymphoproliferative disorders, benign epithelial proliferation, malignant neoplasia, and metastatic disease. Inflammatory lesions and lymphoproliferative disorders are the most common and may be unilateral or bilateral; they may also be localized to the orbit or associated with systemic disease. Both benign and malignant epithelial lacrimal gland masses tend to be unilateral and involve the orbital lobe, but a more rapid onset of symptoms and periorbital pain strongly suggest malignant disease. On orbital imaging, both inflammatory and lymphoproliferative lesions conform to the globe and surrounding structures, without changes in adjacent bone, whereas epithelial lacrimal gland masses often show scalloping of the lacrimal gland fossa. Malignant epithelial lacrimal gland tumors can also have radiographic evidence of bony invasion and destruction. Masses of the lacrimal gland may be due to a broad range of pathologies, and a good working knowledge of common clinical characteristics and radiographic imaging findings is essential for diagnosis and treatment. All patients with inflammatory, lymphoproliferative, and epithelial neoplastic lesions involving the lacrimal gland require long-term surveillance for disease recurrence and progression.

Molecular Pathology of Salivary Gland Neoplasms: Diagnostic, Prognostic, and Predictive Perspective

Salivary gland neoplasms are an uncommon and widely heterogeneous group of tumors. In recent years, there has been considerable progress in efforts to reveal the molecular landscape of these tumors, although it is still limited and appears to be only the tip of the iceberg. Genomic aberrations, especially specific chromosomal rearrangements including CRTC1-MAML2 and CRTC3-MAML2 in mucoepidermoid carcinoma, MYB-NFIB and MYBL1-NFIB fusions in adenoid cystic carcinoma, PLAG1 and HMGA2 alterations in pleomorphic adenoma and carcinoma ex pleomorphic adenoma, ETV6-NTRK3 and ETV6-RET in secretory carcinoma, EWSR1-ATF1 and EWSR1-CREM in clear cell carcinoma, provide new insights into the molecular pathogenesis of various salivary gland neoplasms and help to better classify them. These genetic aberrations primarily serve as diagnostic tools in salivary gland tumor diagnosis; however, some also have promise as prognostic or predictive biomarkers. This review summarizes the latest developments in molecular pathology of salivary gland tumors with a focus on distinctive molecular characteristics.

Invasive Carcinoma Ex-Pleomorphic Adenoma of the Lacrimal Gland with a Cystadenocarcinoma Component: A Case Report and Review of the Literature

Lacrimal gland neoplasms comprise up to 18% of all orbital masses clinically and histologically. Much of our current core knowledge regarding lacrimal gland tumors stems from prior study of their more common counterparts, the salivary glands. The prognosis for each lacrimal gland tumor is contingent upon proper clinical evaluation and ultimately the histopathologic diagnosis. We describe a case of an invasive carcinoma ex-pleomorphic adenoma (Ca-ex-PA) with a cystadenocarcinoma component arising from the lacrimal gland in the absence of any previously diagnosed pleomorphic adenoma (benign mixed tumor) or prior incisional surgery. This case illustrates the importance of the histopathologic assessment including immunohistochemistry and genetic testing to narrow a differential diagnosis and potentially aid or guide therapy in the future. Our finding suggests that carcinoma of the lacrimal gland may be derived from previously undiagnosed and perhaps even subclinical pleomorphic adenoma.

Ductal Adenocarcinoma Ex Pleomorphic Adenoma of the Lacrimal Gland: a Rare and Morbid Malignancy

Carcinoma ex pleomorphic adenoma (Ca ex PA) is a rare malignant transformation of a benign primary pleomorphic adenoma (PA). We report the case of a 62-year-old male who presented with a swelling over his left temple. Imaging revealed a lytic lesion over the left orbital wall with soft tissue extension suggestive of malignancy. He underwent an en bloc resection of the mass with orbital exenteration, craniotomy, and reconstruction. Pathology demonstrated a lacrimal gland ductal adenocarcinoma arising from a PA which led to the diagnosis of ductal adenoCa ex PA. Postoperatively, he received chemotherapy with 6 cycles of cisplatin and concurrent radiation therapy (RT), but his course was complicated by recurrent bacterial meningitis and abscesses and he ultimately opted for comfort measures. Patients with PA of the lacrimal gland experience an insidiously enlarging painless swelling of the orbit with transformation to Ca ex PA highlighted by a rapid onset of bulbar enlargement, displacement, and often proptosis. Ductal adenoCa ex PA is aggressive with a poor prognosis and has no established standard of care. This case highlights the rarity of this condition and the need for more literature to help direct treatment.

Recurrent rearrangements of the PLAG1 and HMGA2 genes in lacrimal gland pleomorphic adenoma and carcinoma ex pleomorphic adenoma

PURPOSE

Lacrimal gland tumours constitute a wide spectrum of neoplastic lesions that are histologically similar to tumours of the salivary gland. In the salivary gland, pleomorphic adenoma (PA) is frequently characterized by recurrent chromosomal rearrangements of the PLAG1 and HMGA2 genes, a genetic feature retained in carcinoma ex pleomorphic adenoma (ca-ex-PA) that makes it possible to distinguish ca-ex-PA from de novo carcinomas. However, whether PLAG1 and HMGA2 gene rearrangements are found in lacrimal gland PA and ca-ex-PA is not known.

METHODS

Twenty-one lacrimal gland PAs and four ca-ex-PAs were retrospectively reviewed and subjected to break-apart fluorescence in situ hybridization (FISH) for rearrangements of the PLAG1 gene. Cases without PLAG1 abnormalities were subjected to HMGA2 break-apart FISH. Immunohistochemical staining for PLAG1 and HMGA2 protein was performed and correlated with gene status.

RESULTS

Sixteen of 21 PAs showed rearrangement of PLAG1 and were all positive for PLAG1 protein. Two of the remaining five PAs showed rearrangement of HMGA2 and were the only cases positive for HMGA2 with immunohistochemistry. The three FISH-negative PAs expressed PLAG1 protein. All four ca-ex-PAs showed rearrangement of PLAG1 and expressed PLAG1 protein. None of the de novo carcinomas showed rearrangement of either of the two genes or expression of the two proteins.

CONCLUSION

Rearrangement of PLAG1 and HMGA2 and expression of the corresponding proteins are frequent and specific findings in lacrimal gland PA and ca-ex-PA. The mechanism for PLAG1 overexpression in FISH-negative PAs is yet to be clarified.

Lacrimal gland tumors in Turkey: types, frequency, and outcomes

AIM

To evaluate the clinical, radiological, and treatment features of lacrimal gland tumors.

METHODS

Retrospective review of 99 eyes of 92 patients with lacrimal gland tumors diagnosed and managed in a single institution between January 1999 and March 2017. Clinical and radiological features, histopathology, treatment methods, and prognosis were evaluated.

RESULTS

The mean patient age was 40.3 (range: 7-80)y. The diagnosis was made histopathologically in 91 (91.9%) tumors and on a clinical and radiological basis in 8 (8.1%) tumors. Final diagnoses included idiopathic orbital inflammation (pseudotumor) in 46 (46.5%) lesions, pleomorphic adenoma in 14 (14.1%), adenoid cystic carcinoma in 12 (12.1%), granulomatous inflammation in 10 (10.1%), lymphoma in 5 (5.0%), benign reactive lymphoid hyperplasia in 3 (3.0%), dacryops in 3 (3.0%), carcinoma ex pleomorphic adenoma in 2 (2.0%), adenocarcinoma in 1 (1.0%), dermoid cyst in 1 (1.0%), cavernous hemangioma in 1 (1.0%), and leukemic infiltration in 1 (1.0%). Non-epithelial tumors comprised 64.6% (n=64) of all lacrimal gland tumors, epithelial tumors 32.3% (n=32), dermoid cyst 1% (n=1), cavernous hemangioma 1% (n=1), and leukemic infiltration 1% (n=1). There were in total 78 (78.8%) benign and 21 (21.2%) malignant tumors.

CONCLUSION

Overall, 65% of lacrimal gland tumors were of non-epithelial origin and 32% of epithelial origin. By histopathology and clinical evaluation, 79% of lacrimal gland tumors were benign. The most common lacrimal gland tumors include idiopathic orbital inflammation (46.5%), epithelial (32.3%), and lymphoproliferative (8.1%) lesions.

[Pleomorphic adenoma of the lacrimal gland in a young girl: a case report]

We present a case of a 13 year old girl with a diagnosis of Pleomorphic Adenoma (PA) located in the lacrimal gland of the left upper eyelid. The patient had a very satisfactory recovery after surgical excision of the tumor, with no recurrence after a two year follow-up. The clinical, radiological and histopathological characteristics of PAs are discussed.

Pleomorphic adenoma of the lacrimal gland: A review with updates on malignant transformation and molecular genetics

Pleomorphic adenoma (benign mixed tumor) is the most common epithelial neoplasm of the lacrimal gland. It is usually a slow growing, well-circumscribed, mass that is identical to its salivary gland counterpart. Patients generally have an excellent prognosis for vision and long-term survival after complete surgical excision. There is a tendency to reoccur, especially if there is an incomplete excision, and rarely, malignant transformation to carcinoma ex pleomorphic adenoma can occur, which has a much poorer prognosis. The molecular genetics of lacrimal gland pleomorphic adenomas have only recently been studies, but appear to display similar genetic aberration found in the salivary gland counterparts.

PLAG1 immunohistochemistry is a sensitive marker for pleomorphic adenoma: a comparative study with PLAG1 genetic abnormalities

AIMS

Pleomorphic adenoma gene 1 (PLAG1) gene rearrangement is the most common genetic abnormality in pleomorphic adenoma (PA), resulting in overexpression of PLAG1 protein. PA and carcinoma ex pleomorphic adenoma (CA ex-PA) can mimic various benign and malignant salivary gland tumours. The aims of this study are to evaluate the sensitivity and specificity of PLAG1 immunohistochemistry (IHC) in the differential diagnosis of PA and CA ex-PA and to compare the PLAG1 immunohistochemical results to PLAG1 gene abnormalities as detected by fluorescence in-situ hybridisation (FISH).

METHODS AND RESULTS

PLAG1 immunostaining was performed on 83 salivary gland tumours, including 23 PA, 15 CA ex-PA and 45 other salivary gland tumours. In addition, PLAG1 FISH was performed in 44 cases for the presence of gene rearrangements/amplifications. The results showed high sensitivity of PLAG1 IHC in 96% of PA; however, discordant results between PLAG1 FISH abnormalities and IHC were noted in 15 of 44 cases (34%). Seven PA, four de-novo myoepithelial carcinomas and one basal cell adenocarcinoma had negative FISH results, but were positive for IHC; while three salivary duct carcinomas (SDC) ex-PA were positive for FISH but negative for IHC. PLAG1 IHC can differentiate CA ex-PA from de-novo SDC (P = 0.02), but not from de-novo myoepithelial carcinoma. PLAG1 IHC is a sensitive marker for PA. This could be due to PLAG1 gene abnormalities beyond FISH resolution.

CONCLUSIONS

A negative PLAG1 IHC might be helpful in excluding a PA diagnosis. Interestingly, in the context of CA ex-PA, FISH is more sensitive than IHC in detecting PLAG1 abnormalities.

HMGA2 is a specific immunohistochemical marker for pleomorphic adenoma and carcinoma ex-pleomorphic adenoma

AIMS

Accurate classification of salivary gland neoplasms may be challenging, owing to morphological overlap, particularly in small biopsies. Recurrent translocations involving the high-mobility group AT-hook 2 (HMGA2) gene are present in a subset of pleomorphic adenomas (PAs) and carcinoma ex-pleomorphic adenomas (CA ex-PAs). The aim of this study was to evaluate immunohistochemical HMGA2 expression in 225 salivary gland tumours, including 56 PAs, 37 CA ex-PAs, and 132 potential histological mimics, to determine its diagnostic utility.

METHODS AND RESULTS

HMGA2 expression was identified in 19 PAs (33.9%) and nine CA ex-PAs (24.3%). Expression was strong and diffuse throughout all PAs, and in four of nine positive CA ex-PAs. In five CA ex-PAs, HMGA2 showed weak-to-strong multifocal staining within the carcinomatous component, and strong diffuse HMGA2 expression in the residual PA. Among histological mimics, six de-novo salivary duct carcinomas (28.5%), three epithelial-myoepithelial carcinomas (33.3%) and one case each of myoepithelioma and basal cell adenoma expressed HMGA2. Fluorescence in-situ hybridization for HMGA2 rearrangement performed on a subset of tumours that showed diffuse HMGA2 expression in PAs and CA ex-PAs was frequently associated with rearrangement of the HMGA2 locus, whereas cases of de-novo salivary duct carcinoma, or CA ex-PA with limited or no HMGA2 expression, had an intact HMGA2 locus.

CONCLUSIONS

HMGA2 expression is a highly specific (96.2%), but low-sensitivity (29.8%), marker for PA and CA ex-PA when compared with histological mimics, and is frequently associated with rearrangement of the HMGA2 locus.

An Update on Tumors of the Lacrimal Gland

Lacrimal gland tumors are rare and constitute a wide spectrum of different entities ranging from benign epithelial and lymphoid lesions to high-grade carcinomas, lymphomas, and sarcomas with large differences in prognosis and clinical management. The symptoms and findings of a lacrimal gland lesion are a growing mass at the site of the lacrimal gland, including displacement of the eyeball, decreased motility, diplopia, and ptosis. Pain is the cardinal symptom of an adenoid cystic carcinoma. Radiological findings characteristically include an oval, well-demarcated mass for benign lesions whereas malignant lesions typically display calcifications, destruction of bone, and invasion of adjacent structures. The diagnosis ultimately relies on histology, as does the choice of treatment and the prognosis. In recent years, the understanding of the biology of numerous types of lacrimal gland neoplasia has improved and the choice of treatment has changed accordingly and holds further promise for future targeted therapies. Treatment of benign epithelial lesions is surgical excision whereas carcinomas often require adjuvant radiotherapy and/or chemotherapy. In contrast, the cornerstone in management of lymphoid lesions is chemotherapy, often including a monoclonal antibody. This article presents an update on the clinical, radiological, histological, and molecular features, along with treatment strategies for tumors of the lacrimal gland.

Myths in the Diagnosis and Management of Orbital Tumors

Orbital tumors constitute a group of diverse lesions with a low incidence in the population. Tumors affecting the eye and ocular adnexa may also secondarily invade the orbit. Lack of accumulation of a sufficient number of cases with a specific diagnosis at various orbital centers, the paucity of prospective randomized studies, animal model studies, tissue bank, and genetic studies led to the development of various myths regarding the diagnosis and treatment of orbital lesions in the past. These myths continue to influence the diagnosis and treatment of orbital lesions by orbital specialists. This manuscript discusses some of the more common myths through case summaries and a review of the literature. Detailed genotypic analysis and genetic classification will provide further insight into the pathogenesis of many orbital diseases in the future. This will enable targeted treatments even for diseases with the same histopathologic diagnosis. Phenotypic variability within the same disease will be addressed using targeted treatments.

The landscape of gene fusions and somatic mutations in salivary gland neoplasms - Implications for diagnosis and therapy

Recent studies of the genomic landscape of salivary gland tumors have provided important insights into the molecular pathogenesis of these tumors. The most consistent alterations identified include a translocation-generated gene fusion network involving transcription factors, transcriptional coactivators, tyrosine kinase receptors, and other kinases. In addition, next-generation sequencing studies of a few subtypes of salivary neoplasms have revealed hotspot mutations in individual genes and mutations clustering to specific pathways frequently altered in cancer. Although limited, these studies have opened up new avenues for improved classification and targeted therapies of salivary gland cancers. In this review, we summarize the latest developments in this field, focusing on tumor types for which clinically important molecular data are available.

Usefulness of translocation-associated immunohistochemical stains in the fine-needle aspiration diagnosis of salivary gland neoplasms

BACKGROUND

Fine-needle aspiration diagnosis of pleomorphic adenoma (PA) and adenoid cystic carcinoma (ACC) is challenging due to cytologic overlap with one another and with other salivary gland tumors having prominent epithelial and myoepithelial components. Recognition of characteristic chromosomal aberrations in several salivary gland tumors, including PA and ACC, has the potential to resolve diagnostic uncertainty, but molecular diagnostics are not routinely available. To leverage these molecular alterations, the authors examined a panel of commercially available immunostains directed at commonly overexpressed proteins in translocation-associated PA (PLAG1 and HMGA2) and ACC (MYB) to assess their diagnostic usefulness.

METHODS

Immunohistochemistry was performed on cell block samples from 74 patients, including 11 ACC specimens and 31 PA specimens with antibodies to MYB, PLAG1, and HMGA2 as well as KIT (previously considered useful in the diagnosis of ACC).

RESULTS

ACCs demonstrated significantly greater staining for KIT compared with non-ACCs, while PAs had significantly greater staining for PLAG1 than non-PAs. MYB trended toward significance for ACC (P=.097) and HMGA2 trended toward significance for PA (P=.094). No ACC exhibited positive staining for PLAG1 or HMGA2. Only 12% of PAs were found to be positive for MYB or KIT. Combined positivity for MYB and KIT with negative PLAG1 and HMGA2 demonstrated a specificity and positive predictive value of 1.0 for ACC, whereas a positive PLAG1 or HMGA2 stain with negative MYB and KIT stains showed a sensitivity of 0.75, a specificity of 0.96, and a positive predictive value of 0.95 for PAs.

CONCLUSIONS

An immunohistochemical panel of MYB, KIT, PLAG1, and HMGA2 on fine-needle aspiration cell blocks is useful in distinguishing ACCs and PAs from each other and other salivary gland neoplasms. Cancer Cytopathol 2016;124:397-405. © 2016 American Cancer Society.

Genomic profiling of a combined large cell neuroendocrine carcinoma of the submandibular gland

A 69-year-old female with no previous medical history presented with a rapidly growing submandibular mass. Fine needle aspiration cytology suggested a small-cell carcinoma and PET-CT showed increased 18-FDG uptake in the submandibular mass as well as in a lung mass. Submandibular resection and selective neck dissection was performed and histopathologic examination revealed a combined large-cell neuroendocrine carcinoma (LCNEC) with a squamous component and without lymph node metastases. Resection of the lung tumor revealed a papillary adenocarcinoma that was morphologically distinctly different from the LCNEC. The patient died of her lung cancer after 19 months without evidence of recurrence of the LCNEC. Genomic profiling of the salivary gland LCNEC revealed a hypodiploid genome predominated by losses of whole chromosomes or chromosome arms involving chromosomes 3p, 4, 7q, 10, 11, 13, 16q and gains of 3q and 16p. In addition, there was a segmental gain of 9p23-p22.3 including the NFIB oncogene. Continued studies of salivary gland LCNEC may provide new knowledge concerning potential diagnostic biomarkers and may ultimately also lead to the identification of new treatment targets for patients with these aggressive carcinomas.

Tumors of the lacrimal gland

Tumors of the lacrimal gland comprise a wide spectrum, of which the most common demonstrate epithelial and lymphoid differentiation. The diagnosis of lacrimal gland tumors depends primarily on histological evaluation, as do the choice of treatment and prognosis. For some lacrimal gland neoplasms, such as adenoid cystic carcinoma, the outlook is grave. Optimal treatment for several lacrimal gland tumors is also a matter of controversy. However, recent progress has been made in the molecular and genetic understanding of tumorigenesis for such lesions. This article presents an overview of the histopathology of lacrimal gland tumors, together with their epidemiological features, clinical characteristics, and treatment strategies.