Sarcomatoid salivary duct carcinoma of the parotid gland

High-grade salivary carcinomas: A current insight on diagnostic pathology and the key to clinical decision making

High-grade carcinomas of the salivary glands are a group of several tumor entities with highly malignant histologic appearances, and have an aggressive biological behavior accompanied by poor a prognosis. In general, they require more intensive treatment than low- or intermediate-grade carcinomas. High-grade salivary carcinomas are rare and the microscopic features often overlap between different tumor types, making an appropriate diagnosis challenging in daily practice settings. However, with recent rapid advances in molecular pathology and molecular-targeted therapy in this field, there is a growing need to properly classify tumors, rather than just diagnosing the cases as "high-grade carcinomas". This leads to specific treatment strategies. In this article, we review representative high-grade salivary gland carcinomas, including salivary duct carcinoma and its histologic subtypes, high-grade mucoepidermoid carcinoma, solid-type adenoid cystic carcinoma, and high-grade transformation of low- or intermediate-grade carcinomas, and discuss their differential diagnoses and clinical implications. Other rare entities, such as neuroendocrine carcinoma, NUT carcinoma, and metastatic carcinoma, should also be considered before diagnosing high-grade carcinoma, NOS. Of these tumors, salivary duct carcinoma has received the most attention because of its strong association with androgen deprivation and anti-HER2 therapies. Other tumor-type-specific treatments include anti-TRK therapy for high-grade transformation of secretory carcinoma, but further therapeutic options are expected to be developed in the future. It should be emphasized that detailed histological evaluation with adequate sampling, in addition to the effective use of molecular ancillary tests, is of the utmost importance for a suitable diagnosis.

Salivary Duct Carcinoma with Rhabdoid Features of the Parotid Gland with No E-Cadherin Expression: A Report with Anti-HER2 Therapy and Review of the Literature

Salivary duct carcinoma with rhabdoid features (SDC-RF) is a rare form of salivary gland neoplasm that was recently described. We report a case of SDC-RF of the parotid gland with loss of E-cadherin and decreased β-catenin expression in a 73-year-old male who presented with right facial/neck swelling and intermittent pain. Morphologically, the tumor presented with a discohesive infiltrate of isolated and cords of pleomorphic round cells containing moderate amount of eosinophilic to fine-vacuolated cytoplasm and hyperchromatic nuclei infiltrating through fibroadipose tissue and salivary parenchyma. Immunophenotypically, the tumor was positive for Cytokeratins Oscar and 7, GATA3, GCDFP, HER2, and an androgen receptor but negative for CK20, S100, p40, Melan A, CDX2, TTF1, ER, SATB2, DOG1, synaptophysin, and chromogranin. Due to its diffuse infiltrating pattern, involvement of the parapharyngeal space, supraclavicular fat pad, dermis, and skin without a defined surgical target, the tumor was deemed unresectable. Anti-HER2 therapy (Herceptin and Pertuzumab) was utilized. At the last follow-up, the patient is alive, with complete locoregional control and brain metastases. An electronic search was performed in the following registries for papers published up to June 2023: PubMed, Embase, and Web of Science. For the database searches, the keywords searched were "salivary gland", "salivary duct carcinoma", and "salivary duct carcinoma with rhabdoid features". Our review of the literature identified 30 cases of SDC-RF that reveal there is a predilection for males (83%), parotid gland (72%), and patients older than the 6th decade of life (83%). Immunophenotypically, all SDC-RF cases except one were positive for AR and GCDFP (97%), 81% were positive for HER2, and loss or decreased expression of E-cadherin in 93% of cases. In conclusion, we described a rare case of SDF-RF of the parotid gland with no E-cadherin expression, decreased β-catenin expression, and its immunophenotypic profile.

Salivary carcinosarcoma: insight into multistep pathogenesis indicates uniform origin as sarcomatoid variant of carcinoma ex pleomorphic adenoma with frequent heterologous elements

AIMS

The formal pathogenesis of salivary carcinosarcoma (SCS) remained unclear, both with respect to the hypothetical development from either preexisting pleomorphic adenoma (PA) or de novo and the clonal relationship between highly heterogeneous carcinomatous and sarcomatous components.

METHODS AND RESULTS

We performed clinicopathological and molecular (targeted RNA sequencing) analyses on a large series of 16 cases and combined this with a comprehensive literature search (111 cases). Extensive sampling (average 11.6 blocks), combined with immunohistochemistry and molecular studies (PA-specific translocations including PLAG1 or HMGA2 proven in 6/16 cases), enabled the morphogenetic identification of PA in 15/16 cases (93.8%), by far surpassing a reported rate of 49.6%. Furthermore, we demonstrated a multistep (intraductal/intracapsular/extracapsular) adenoma-carcinoma-sarcoma-progression, based on two alternative histogenetic pathways (intraductal, 56.3%, versus myoepithelial pathway, 37.5%). Thereby, early intracapsular stages are identical to conventional carcinoma ex PA, while later extracapsular stages are dominated by secondary, frequently heterologous sarcomatous transformation with often large tumour size (>60 mm).

CONCLUSION

Our findings strongly indicate that SCS (almost) always develops from PA, with a complex multistep adenoma-carcinoma-sarcoma-sequence, based on two alternative histogenetic pathways. The findings from this novel approach strongly suggest that SCS pathogenetically is a rare (3-6%), unique, and aggressive variant of carcinoma ex PA with secondary sarcomatous overgrowth. In analogy to changes of terminology in other organs, the term "sarcomatoid carcinoma ex PA with/without heterologous elements" might be more appropriate.

Targeted molecular profiling of salivary duct carcinoma with rhabdoid features highlights parallels to other apocrine and discohesive neoplasms: which phenotype should drive classification?

BACKGROUND

Salivary duct carcinoma with rhabdoid features (SDC-RF) is a recently-described salivary gland tumor that bears striking histologic similarity to lobular carcinoma of the breast. While this tumor has an apocrine phenotype that supports classification as a variant of SDC, it infrequently arises in association with conventional SDC. Furthermore, discohesive architecture can be seen in non-apocrine salivary carcinomas, raising the possibility that discohesive growth should define a separate entity. In this study, we aimed to perform comprehensive molecular profiling of SDC-RF to better understand its pathogenesis and classification.

METHODS

We documented the clinicopathologic features of 9 cases of SDC-RF and performed immunostains including AR, GCDFP, and e-cadherin on all cases. We also performed targeted next generation sequencing (NGS) panels on 7 cases that had sufficient tissue available.

RESULTS

The SDC-RF represented 8 men and 1 woman with a median age of 67 years (range 63-83 years) and included 6 parotid, 2 buccal, and 1 submandibular primary. All tumors were uniformly composed of discohesive cells with abundant eosinophilic cytoplasm; signet-ring cell features were seen in 2 cases. All tumors were also positive for AR (100%) and GCDFP (100%), and 7 tumors (78%) displayed lost or abnormal e-cadherin. NGS highlighted concomitant PIK3CA and HRAS mutations in 4 tumors, with additional cases harboring TP53, PTEN, and AKT1 mutations. Furthermore, CDH1 alterations were seen in 6 cases, including a novel CDH1::CORO7 fusion. Among 5 patients with follow-up available, 3 (60%) developed local recurrence and widespread distant metastasis and died of disease at a median 20 months (range 10-48 months).

CONCLUSIONS

Overall, our findings confirm frequent CDH1 mutations and e-cadherin inactivation in SDC-RF, similar to discohesive tumors from other sites. We also highlight an apocrine molecular profile similar to conventional SDC. However, occasional AKT1 mutation and signet-ring features suggest SDC-RF may also be related to mucinous adenocarcinoma. As more salivary tumors with discohesive growth are identified, it may become clearer whether SDC-RF should remain in the SDC family or be recognized as a separate entity.

Salivary duct carcinoma: A report of 70 FNA cases and review of the literature

BACKGROUND

Although usually recognized as malignant, fine-needle aspiration (FNA) biopsy of salivary duct carcinoma (SDC) has been confused with other primary salivary gland (SG) neoplasms. This article undertook an analysis of a large collection of SDC FNA cases to assess diagnostic accuracy, specificity, and cytopathology.

METHODS

Cytopathology files were searched for SDC with histopathologic validation. FNA biopsy smears were performed using standard techniques.

RESULTS

Seventy cases from 56 patients (M:F, 1.9:1; age range, 26-92 years; mean age, 65 years) met inclusion criteria. All had tissue confirmation of SDC. FNA sites included: parotid gland (42, 60% cases), neck (10), submandibular gland (7), pre-/post-auricular area (5), face/cheek (3), mediastinal lymph nodes (2), and clavicle (1). Aspirates were from primary (52, 74%), metastatic (12, 17%), and locally recurrent (6, 9%) neoplasms. FNA diagnoses included: SDC (19, 27%), favor/suspicious for SDC (7, 10%), high-grade carcinoma (11), adenocarcinoma (9), carcinoma (6), malignant (6), SG neoplasm (5), atypia (3), SDC versus another malignancy (2), and pleomorphic adenoma (2). Large polygonal cells in groups and single forms showed cribriforming, variable necrosis, pseudopapillae, and oncocytic change. Androgen receptor staining was positive in all cases.

CONCLUSIONS

FNA biopsy is accurate and reliable in classifying SDC as a malignant neoplasm, but much less so for identification as a specific tumor type. Using the Milan system, 86% of aspirates were classified as either malignant or suspicious for malignancy. A recurring pitfall includes sampling error in cases of SDC ex pleomorphic adenoma.

Giant Cell Carcinosarcoma of the Parotid Gland With a PLAG 1 Translocation in Association With a Pleomorphic Adenoma With HMGA2 Translocation

OBJECTIVES

Carcinosarcomas of the salivary gland are rare neoplasms and have been described arising de novo or in association with pleomorphic adenoma (PA). PLAG1 and HMGA2 translocations are known to occur in PAs and carcinomas ex PA but are mutually exclusive.

METHODS

We report a case of a carcinosarcoma in the parotid gland of a 77-year-old man with unusual anaplastic sarcomatoid giant cell morphology.

RESULTS

Microscopically, a small separate PA was found adjacent to the carcinosarcoma. By conventional notion, the PA and carcinosarcoma would be considered related, as carcinosarcomas are well known to arise from PAs (carcinosarcoma ex PA). However, fluorescence in situ hybridization (FISH) assay demonstrated PLAG1 translocation in the carcinosarcoma and HMGA2 translocation in the separate PA.

CONCLUSIONS

These findings support that the carcinosarcoma likely originated from another PA with a PLAG1 translocation or de novo but not from the coexisting PA harboring a different translocation. To our knowledge, the case is the first to demonstrate PLAG1 translocation by FISH in a sarcomatous component of any parotid gland tumor, which may help better classify these tumors. In addition, multiple PAs are commonly found in the salivary gland, and to our knowledge, our case is the first to demonstrate that the same parotid gland can host PAs and PA-related tumors with different translocations.

PD-L1 expression by immunohistochemistry in salivary duct carcinoma

BACKGROUND

Immune checkpoint inhibitors play an increasing role in oncologic care. PD-L1 expression is associated with survival and predicts response to PD-1 or PD-L1 inhibitors in a variety of tumors. Our aim is to evaluate the frequency and prognostic significance of PD-L1 expression in salivary duct carcinoma.

DESIGN

We retrospectively evaluated the expression of PD-L1 by two different antibodies (PD-L1 28-8 and PD-L1 22C3) in salivary duct carcinomas. PD-L1 expression in at least 1% of tumor cells was considered immunoreactive. Kaplan-Meier analysis was performed to determine the impact of PD-L1 expression on survival; differences between survival curves were assessed by the chi-square test, and pairwise comparisons of factors were assessed with the log-rank test.

RESULTS

A total of 113 patients' specimens were evaluated. Seventy-six (76%) of the patients were male. Mean age at time of presentation was 61.2 (SD = 12.4) years. PD-L1 expression was found in 26% of the samples. Median follow-up time was 36.6 months (range = 1.4-249 months). Overall survival at 3, 5 and 10 years were 52.6%, 37.9% and 25.6%, respectively. There was no statistical difference in survival between patients with PD-L1-immunoreactive tumors and those without, regardless of which antibody was used (chi² result for all plots: p = 0.53; log rank test for pairwise comparison: p > 0.256).

CONCLUSION

In our analysis, PD-L1 expression occurred in a small proportion of salivary duct carcinomas, usually at low levels, and did not correlate with survival. Its predictive value and utility in selecting patients with salivary duct carcinoma who might benefit from PD-1/PD-L1 inhibitors warrants further investigation.

Salivary Duct Carcinoma: An Update on Morphologic Mimics and Diagnostic Use of Androgen Receptor Immunohistochemistry

More than 15 years ago, seminal studies by Dr. E. Leon Barnes and colleagues transformed our understanding of salivary duct carcinoma (SDC) and, in doing so, paved the way for contemporary diagnostic and therapeutic approaches to this aggressive salivary adenocarcinoma. In particular, attention to the apocrine phenotype of SDC and expression of androgen receptor (AR) by immunohistochemistry has improved the diagnostic accuracy and showed how SDC can be reliably distinguished from its morphologic mimics (i.e., other salivary gland carcinomas with high grade transformation, low grade cribriform cystadenocarcinoma, and squamous cell carcinomas involving parotid). Furthermore, the observation that SDC shares AR expression with prostate cancer and apocrine breast cancer foresaw the discovery of common molecular alterations between SDC and these tumor types and draw attention to androgen deprivation therapy for SDC patients.

Salivary duct carcinoma with rhabdoid features: a salivary counterpart of pleomorphic lobular carcinoma of the breast

AIM

To analyse the clinicopathological features and immunohistochemical characteristics of nine cases of salivary duct carcinoma (SDC) with rhabdoid features (SDCRF), representing a new, extremely rare type of salivary gland malignancy.

METHODS AND RESULTS

We analysed 2511 cases of salivary gland tumour, clinicopathologically and immunohistochemically. The incidence of SDCRF was 0.4%. Eight patients were male. The age of patients ranged from 36 years to 85 years (mean, 61 years). SDC arose from the parotid glands and submandibular gland in six and three cases, respectively. Seven cases appeared as a carcinoma component of carcinoma ex pleomorphic adenoma cases. Six patients died of disease. Histologically, diffuse proliferations of non-coherent large ovoid or polygonal carcinoma cells with eosinophilic cytoplasm and eccentric nuclei were observed in all cases; such cytological characteristics were defined as 'rhabdoid features'. Immunohistochemically, all cases were positive for cytokeratin, gross cystic disease fluid protein-15, androgen receptor, and SMARCB1, seven cases were positive for HER2, and two cases were positive for epidermal growth factor receptor. However, all cases were negative for vimentin and myoepithelial markers. Eight cases showed no or aberrant expression of E-cadherin and β-catenin. The results suggest that SDCRF is an extremely rare subtype of SDC, and not a sarcomatoid variant of SDC. SDCRF is histologically unique, and is positive for SDC markers but negative for vimentin, unlike rhabdoid-type carcinomas arising from other organs.

CONCLUSIONS

The morphogenesis of SDCRF is related to no or aberrant expression of cell-cell adhesion molecules. Therefore, SDCRF could be a salivary counterpart to pleomorphic lobular breast carcinoma.

Salivary duct carcinoma in the mandibular anterior region: The role of immunohistochemical markers in its definitive diagnosis

Salivary duct carcinoma (SDC) is a high-grade adenocarcinoma arising from the ductal epithelium of salivary glands which rarely involves the minor salivary glands. The varied histological presentation in the minor salivary gland tumors makes them the most heterogeneous group of neoplasms, making the diagnosis a challenge. This report highlights the importance of immunohistochemical markers in the definitive diagnosis of SDC.

Salivary duct carcinoma: the predominance of apocrine morphology, prevalence of histologic variants, and androgen receptor expression

Salivary duct carcinoma (SDC) is a prototypic aggressive salivary gland carcinoma. Our aim is to determine the prevalence of histologic variants (micropapillary, basal-like) and androgen receptor (AR) expression in a large multi-institutional series of SDC. AR status was determined by immunohistochemistry (IHC). Most SDCs were characterized by an apocrine phenotype and AR expression. Cases with a nonapocrine phenotype and AR-negative status were studied by additional IHC and fluorescence in situ hybridization for ETV6 or MYB/NFIB. The diagnosis of SDC was confirmed in 187 of 199 (94%) cases. Variant morphologies were identified in 12 cases: micropapillary (n=6), sarcomatoid (n=3), mucinous (n=2), and basal-like (n=1). AR IHC was performed in 183 cases, of which 179 (97.8%) showed AR expression. On the basis of morphologic appearance and results of additional studies, 12 cases were reclassified as squamous cell carcinoma (SCC) (n=4), epithelial-myoepithelial carcinoma with high-grade transformation (HGT) (n=2), myoepithelial carcinoma (n=2), mammary analogue secretory carcinoma, high grade (ETV6 translocated; n=1), adenoid cystic carcinoma with HGT (n=1), acinic cell carcinoma with HGT (n=1), and adenosquamous carcinoma (n=1). AR-negative SDC is extremely rare, and the majority of such cases are more accurately classified as other entities. HGTs of other salivary carcinomas and squamous cell carcinoma are the most common mimics of SDC. SDCs with variant morphologies still show at least a minor component of conventional apocrine appearance. Thus, apocrine morphology defines SDC.

Sarcomatoid salivary duct carcinoma of the palate: a rare case report

Salivary duct carcinoma (SDC) is an uncommon neoplasm that most commonly occurs in major salivary glands, mainly the parotid gland. SDC is rarely found in the minor salivary glands of the oral cavity. This report presents an extremely rare case of sarcomatoid SDC originating in a minor salivary gland of the palate. The tumor was histologically characterized by the presence of both carcinomatous and sarcomatoid components. The patient presented with a painless mass in the right palate, which slowly increased in size over 20 years. The clinical course of the present case suggests that the tumor most probably developed as a result of malignant transformation of a preexisting benign tumor of the palatal salivary gland. This report describes the clinical and histologic features of this extremely rare case of sarcomatoid SDC with reference to the relevant literature.

Recent advances in the diagnostic pathology of salivary carcinomas

This review concentrates on the most important developments since the WHO classification of 2005. In particular, the identification of specific translocations is revolutionising the way salivary tumours are considered and will have a major impact on future diagnostic practice. This is true so far in four malignancies: mammary analogue secretory, mucoepidermoid, adenoid cystic and hyalinising clear cell carcinomas. In each, the gene rearrangement is found in 80 % or more of cases. Two 2014 publications have added further possible candidates with molecular abnormalities to the list (cribriform adenocarcinoma of the tongue and minor salivary glands and epithelial-myoepithelial carcinoma), but these findings have yet to be confirmed by other investigators. The advances in molecular pathology have also allowed re-evaluation of the morphology; for example, it is now realised that the histological spectrum of hyalinising clear cell carcinoma includes intracellular mucin in over half of cases, as well as tumours with only scanty clear cells. In a separate development, it is now proposed that salivary duct carcinoma can be subdivided along molecular lines, in ways analogous to breast cancer, suggesting new therapeutic prospects in an otherwise highly aggressive malignancy.

Salivary duct carcinoma with rhabdoid features: report of 2 cases with immunohistochemical and ultrastructural analyses

BACKGROUND

Salivary duct carcinoma with rhabdoid features is extremely rare.

METHODS

We report 2 cases of salivary duct carcinoma with rhabdoid features treated at our institution.

RESULTS

Case 1 was a 44-year-old Japanese man who had swelling in the left parotid region. This tumor consisted of residual pleomorphic adenoma and widely invasive carcinoma, which showed a diffuse growth pattern by atypical rhabdoid cells. Case 2 was a 66-year-old Japanese man who had swelling of the right cervical region. This submandibular tumor was also composed of both residual pleomorphic adenoma region and invasive adenocarcinoma components, whereas some metastatic lesions were purely composed of rhabdoid cells. Such cells were strongly and diffusely positive for cytokeratins (CKs), gross cystic disease fluid protein-15 (GCDFP), and androgen receptor (AR). Case 1 was also positive for Her-2 and p53.

CONCLUSION

Both patients were diagnosed with carcinoma ex pleomorphic adenoma and their carcinomatous components were composed of salivary duct carcinoma with rhabdoid features, which is a highly aggressive tumor, similar to salivary duct carcinoma.

Salivary duct carcinoma: new developments--morphological variants including pure in situ high grade lesions; proposed molecular classification

Salivary duct carcinoma (SDC) is an aggressive primary salivary malignancy which microscopically resembles high-grade ductal carcinoma of the breast, with both in situ and invasive patterns. It is typically found in older men, most often in the parotid. It can arise de novo or as the malignant component of carcinoma ex pleomorphic adenoma. SDC is generally a hematoxylin and eosin stain-based diagnosis, with special stains and immunohistochemistry acting mainly in a confirmatory role. Other than epithelial markers, SDC expresses androgen receptors in most cases, with true HER2 positivity seen in about 15 %. Based on these data and analogous to similar schemes in the breast, it is suggested that SDCs can be classified into three main groups: luminal androgen receptor positive, HER2+ and basal phenotype. This may form the basis for prognostic information and new therapeutic possibilities. In addition to the usual type of SDC, a few less common morphological variants have been reported: papillary, micropapillary, mucin-rich, sarcomatoid and oncocytic, as well as pure in situ cases.

Management of sarcomatoid salivary duct carcinoma of the submandibular gland duct with coexisting seropositive human immunodeficiency virus

BACKGROUND

Sarcomatoid salivary duct carcinoma of the submandibular gland is extremely rare. This paper highlights the impact of surgery and adjuvant radiation therapy on the outcome of this disease.

METHODS

A 59-year-old man with human immunodeficiency virus presented with a painless, rapidly growing left neck mass. Biopsy followed by surgical excision of the left submandibular gland revealed sarcomatoid salivary duct carcinoma of the submandibular gland duct with perineural invasion and close margins, for which he underwent adjuvant radiotherapy. Post-operative positron emission tomography and computed tomography revealed no residual or metastatic disease. Pathological analysis of tumour-node-metastasis staging revealed a T2 N0 M0 (stage II) tumour.

RESULTS

The patient tolerated his treatment without serious acute or long-term side effects. There was no evidence of disease on comprehensive examination or on positron emission tomography or computed tomography scans at the 4.6-year follow up.

CONCLUSION

Surgery followed by adjuvant radiotherapy provided practical locoregional control with acceptable toxicity. Further detailed case reports are warranted to optimise the management of this rare malignancy.

A mucin-rich variant of salivary duct carcinoma with a prominent mucinous component, a tumor that mimics mucinous adenocarcinoma

The mucin-rich variant of salivary duct carcinoma (mSDC) is a rare type of salivary duct carcinoma. mSDC usually has both conventional SDC and mucinous adenocarcinoma-like areas. This article describes a first case of mSDC in which 95% of the tumor consisted of a mucinous area without no solid conventional SDC, so that the tumor mimicked mucinous adenocarcinoma. A 55-year-old man was evaluated for a 14 mm mass in the left submandibular gland. The tumor showed that floating tumor nests in a prominent mucinous lake. Some floating tumor nests had focal cribriform pattern with comedo necrosis, and all tumor cells had immunoreactivity for androgen receptor, gross cystic disease fluid protein 15, and Her-2/neu. A diagnosis of mSDC was rendered. mSDC with prominent mucinous component sometimes resembles mucinous adenocarcinoma. Identifying specific histological and immunohistochemical features of floating tumor nests in the mucinous area are important for the diagnosis.

Anaplastic myoepithelial carcinoma of the sinonasal tract: an underrecognized salivary-type tumor among the sinonasal small round blue cell malignancies? Report of one case and a review of the literature

We present a 45 year old female patient with a nasal carcinoma showing high-grade/anaplastic histomorphological features and with a distinct myoepithelial immunohistochemical phenotype including positivity for smooth muscle actin, p63, S100 protein with no sustentacular pattern, calponin, cytokeratin 14, vimentin and cytokeratins (AE1-3 and CK5/6). A minority (<5%) of the cells showed focal and variable immunoreactivity for EMA with no cuticular/canalicular pattern. Bcl-2, CD99, CD117 and CD56 were variously positive, but chromogranin and synaptophysin were negative. Weak to moderate nuclear p53 immunoreactivity was seen in 50% of tumor cells. Mib-1/Ki-67 showed an average proliferation of 60-70%. Fluorescent in situ hybridization revealed no EWS-gene translocation. In situ hybridization for EBER was negative.

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.

Advances in salivary gland pathology

This review summarizes the new findings on salivary gland pathology under the following categories: immunohistochemistry; molecular genetics; newly recognized tumour types; known tumour entities with new findings; and progression of salivary gland tumours. In the application of immunohistochemistry, CD117 can aid in highlighting the luminal cell component of various salivary gland tumours, whereas p63 or maspin can aid in highlighting the abluminal cell component. A high Ki67 index remains the most useful marker to predict adverse outcome in salivary gland carcinoma. Specific chromosomal translocations are recognized in pleomorphic adenoma (with translocation involving PLGA1 or HMGA2 gene) and mucoepidermoid carcinoma (with MECT1-MAML2 gene fusion). Newly recognized entities include: sclerosing polycystic adenosis (with recent molecular evidence supporting its neoplastic nature), sclerosing mucoepidermoid carcinoma with eosinophilia, keratocystoma, adenoma with additional stromal component (lymphadenoma, lipoadenoma and adenofibroma), cribriform adenocarcinoma of the tongue and signet ring adenocarcinoma of minor salivary gland. Known tumour entities with new findings include: salivary duct carcinoma (with newly recognized mucinous, micropapillary and sarcomatoid variants), intraductal carcinoma (with controversies in terminology), mucoepidermoid carcinoma (with newly proposed grading parameters and oncocytic variant), epithelial-myoepithelial carcinoma (with newly recognized morphological variants), small cell carcinoma (with most cases being related to Merkel cell carcinoma), extranodal marginal zone B-cell lymphoma (with specific chromosomal translocation) and chronic sclerosing sialadenitis (being a component of IgG4-related sclerosing disease). Progression of salivary gland tumours can take the form of malignant transformation of a benign tumour, progression from low-grade to high-grade carcinoma, dedifferentiation, or stromal invasion of an in situ carcinoma.

Insights into a complex group of neoplastic disease: advances in histopathologic classification and molecular pathology of salivary gland cancer

Cancers of major and minor salivary glands represent a histopathologic challenge in two major respects. The first challenge is the complexity of morphologic features and overlapping of histologic patterns in the different tumor entities many of which are relatively rare. The number of separate tumor entities to be considered in differential diagnosis has greatly increased in the two latest WHO classification systems 12 (Table I). The second challenge is prognostication based on histopathology. The clinical experience is that behavior of some salivary gland carcinomas does not correlate well with their histopathologic classification, and that tumors classified within the same category may exhibit quite different clinical outcomes. However, recent advances in histopathological classification have been combined with new tools in immunohistochemical diagnosis and prognostication including cell-proliferation markers, myoepithelial antigens, matrix metalloproteinases, steroid receptors, growth factors and their receptors. These have improved our possibilities for more specific choices in the treatment of a variety of salivary gland carcinomas. This paper will give an overview on recent developments in histopathological classification, prognostication, and molecular pathology of salivary gland cancer.

Carcinosarcoma de novo of the parotid gland

Only 29 cases of salivary gland carcinosarcoma de novo have been described in the English-language literature. We present a new case of parotid gland carcinosarcoma de novo and discuss diagnostic and treatment modalities of this pathologic entity. Our patient underwent total parotidectomy with facial nerve preservation, chemotherapy, and radiotherapy. At 26-month follow-up, the patient presented no evidence of recurrence. One-third of the cases of salivary carcinosarcoma de novo died of the disease after a median period of 10 months. Although the number of cases is limited, the combination of radical surgical excision and radiotherapy seems currently the treatment of choice.

Sarcomatoid carcinoma of the parotid gland with apparent metastasis of epidermoid elements to cervical lymph nodes

A case of sarcomatoid carcinoma of the parotid gland is described in a 47-year-old male. Despite radical surgery and postoperative chemoradiation therapy, a distant metastasis occurred 1 month after treatment. The primary site was composed of well-differentiated squamous cell carcinoma intermingled with spindle-shaped malignant mesenchymal cells. Immunohistochemical studies showed that keratin was present in both epithelial cells and spindle cells, whereas vimentin was present in spindle cells and absent in epithelial cells. Two lymph nodes were metastasized by the epidermoid component. The origin of the sarcomatoid component and the differential diagnosis from malignant mixed tumours are discussed.

Sarcomatoid salivary duct carcinoma

The so-called sarcomatoid salivary duct carcinoma (SSDC) is one of the variants of salivary duct carcinoma (SDC). This neoplasm is characterized by the presence of both a carcinomatous and a sarcomatoid tumor component. The histology and nomenclature of such neoplasms has been a matter of debate for many years. The histologic, immunohistochemical, and electron microscopic findings including those of 4 previously described cases of SSDC are defined and the different attitudes concerning their etiology will be discussed. In addition, the fine-needle aspiration biopsy of such a case is presented for the first time. In analogy to typical SDC there seems to be a predilection for elderly men and a location in major salivary glands. The resected SSDC tumors measured between 1.5 and 3.5 cm. Histologically, each case was a composite of SDC and sarcomatoid carcinoma. Immunohistochemical positivity for epithelial membrane antigen (EMA) and cytokeratins (AE1/AE3, CAM 5.2) was shown in the sarcomatoid tumor component. The important cytomorphologic feature of SSDC is the presence of cohesive clusters and flat sheets of cells with a cribriform pattern, in combination with an atypical spindle cell component. The use of the term SSDC seems more appropriate than the term carcinosarcoma , as the immunohistochemical, electron microscopic, and recent molecular findings in this and other biphasic neoplasms imply a monoclonal origin.

Invasive micropapillary salivary duct carcinoma: a distinct histologic variant with biologic significance

An invasive micropapillary component has been described in tumors of several organs and is nearly always associated with aggressive biologic behavior. We present 14 cases of salivary duct carcinoma (SDC) with an invasive micropapillary component (invasive micropapillary SDC) and compare the clinicopathologic findings of these cases with those of cases of conventional SDC. The mean age of the 14 patients (10 men, 4 women) was 65.8 years (range, 26-80 years). The mean size of the tumors was 2.4 cm (range, 1.3-5 cm). The parotid gland was involved in 12 patients and the submandibular gland in 2. Histologically, all tumors had an invasive micropapillary architecture admixed with features typical for SDC. Invasive micropapillary carcinoma was characterized by morula-like small cell clusters without fibrovascular cores, surrounded by a clear space. Tumor cells exhibited moderate- to high-grade nuclear features, conspicuous nucleoli, and eosinophilic cytoplasm. This component was distributed diffusely in 9 tumors and focally in 5. Angiolymphatic and perineural invasion was seen in all tumors. A residual pleomorphic adenoma was detected in four tumors. Of the 12 tumors examined, all were diffusely positive for cytokeratin 7 and epithelial membrane antigen (with a distinctive "inside-out" pattern) but negative for cytokeratin 20. Tumors were frequently immunoreactive for BRST-2 (gross cystic disease fluid protein-15) and androgen receptor protein. Aberrant expression of HER-2/neu or p53 was detected in seven tumors each. The mean Ki-67 labeling index was 33.1% (range, 6.3%-61.6%). All 14 patients with invasive micropapillary SDC had cervical or periglandular lymph node metastasis, and this value was significantly higher than for conventional SDCs. Local recurrence developed in 4 patients and distant metastatic disease in 9. Clinical follow-up (mean, 25.5 months) was available for 13 patients: 9 died of disease within 24 months after the diagnosis (mean, 17.6 months), 1 was alive with metastatic disease at 19 months, and 3 were free of disease. Overall survival of these patients with invasive micropapillary SDC was significantly shorter than that of patients with conventional SDC (n = 49) in our series (P = 0.031). Our results suggest that invasive micropapillary SDC is a distinct, aggressive variant of SDC, with a propensity for extensive lymph node metastasis and rapid disease progression.

Sarcomatoid salivary duct carcinoma of the oral cavity

This report recounts a new case of sarcomatoid variant of salivary duct carcinoma in a 45-year-old woman. The 1.5-cm polypoid mass protruded from the retromolar area and focally extended into the pharyngeal wall. The patient was free of disease for 11 years. The tumor showed a biphasic malignancy; nondescript sarcomatous proliferation predominated over ductal carcinoma population, with perceptible blending of the two components. The sarcomatoid areas had no heterologous properties. Discohesive pleomorphic cells were immunopositive for vimentin, epithelial membrane antigen and AE1/AE3 at a significant rate. A dual expression of AE1/AE3 and vimentin was also evident in enmeshed foci of conventional cribriform adenocarcinoma. Thus, the sarcomatoid histology represents a dedifferentiated phenotype of salivary duct carcinoma.

Mucin-rich variant of salivary duct carcinoma: a clinicopathologic and immunohistochemical study of four cases

Salivary duct carcinoma is a relatively uncommon aggressive neoplasm, typically found in the parotid glands of older men. The histologic appearance is that of an in situ and invasive high-grade adenocarcinoma, and it closely resembles ductal carcinoma of the breast. Several variants of the latter are very well known, but only papillary, sarcomatoid, and low-grade subtypes have so far been reported in salivary duct carcinoma. This study describes the clinicopathologic and immunohistochemical findings in four examples of an additional previously undescribed variant, rich in mucin. Each tumor showed areas of typical salivary duct carcinoma, but in addition there were lakes of epithelial mucin-containing malignant cells, i.e., mucinous (colloid) carcinoma. All four tumors expressed androgen receptors, cytokeratins, epithelial membrane antigen, gross cystic disease fluid protein-15, and carcinoembryonic antigen, but S-100 protein, other myoepithelial markers, and estrogen and progesterone receptors were negative. The mucin antigen profile showed positivity for MUC2, MUC5B, and MUC6 in all cases but only rare staining with MUC5AC and MUC7. Strong immunohistochemical overexpression of HER2/neu was demonstrated in one tumor, together with amplification by fluorescence in situ hybridization; another case was weakly positive with just one antiserum, but the remaining two tumors were completely negative. Small quantities of mucin have often been described in salivary duct carcinoma but not large extracellular mucinous lakes, which though prominent in the present series, were not as extensive as in mucinous adenocarcinoma. The relatively poor clinical outcome of the patients in our study mirrored that seen in usual-type salivary duct carcinoma and emphasizes the importance of differentiating mucin-rich salivary duct carcinoma from pure mucinous (colloid) adenocarcinoma, a tumor not fully defined, but possibly with a better prognosis.