Hybrid carcinomas of salivary glands. Report of 4 cases and review of the literature

Squamoglandular Variant of Acinic Cell Carcinoma: A Case Report of a Novel Variant

While salivary gland tumors have considerable plasticity, juxtaposition of the morphologies of two named tumor types is rare. Tumors with both mucoepidermoid and serous acinar components, dubbed "mucoacinar" carcinomas were recently characterized, and based on morphologic and molecular features, considered variants of mucoepidermoid carcinoma. Here we describe a unique case of a 59-year-old male with a 0.9 cm right parotid mass with a similar blend of mucoepidermoid-like and acinar elements that instead has a molecular phenotype of acinic cell carcinoma, essentially the reverse of mucoacinar carcinoma. The tumor was fairly well circumscribed with a prominent tumor associated lymphoid response. It consisted of a predominant bland but basaloid squamoid proliferation with scattered pockets of serous acinar differentiation as well as rare mucous cells and tubules. The tumor showed diffuse cytokeratin and DOG1 reactivity as well as p40 expression in the squamoid components. Immunostaining for NR4A3 was diffusely positive, and an NR4A3 rearrangement was noted on fluorescence in situ hybridization, while testing for MAML2 and MSANTD3 rearrangements were negative. Based on these findings, this tumor is best considered a "squamoglandular variant of acinic cell carcinoma." Morphologic and clinical evidence argues against this representing a form of high-grade transformation. While overall bland, the differential diagnosis may include various basaloid tumors in the parotid gland, both primary and metastatic.

Hybrid Carcinoma of the Parotid Gland: An Extremely Rare Three Cases with an Immunohistochemical Analysis and a Review of the Literature

Salivary hybrid carcinoma (HC) is defined as when two or more kinds of carcinoma exist at the same location in a single mass. We reestimated and examined three cases of salivary gland HC. Case 1 involved a 76-year-old male. Case 2 involved a 74-year-old female. Case 3 involved a 66-year-old male. Histologically, case 1 involved a combination of salivary duct carcinoma (SDC) and squamous cell carcinoma (SqCC). Immunohistochemically, the former was positive for gross cystic disease fluid protein (GCDFP)-15 and androgen receptor (AR). Case 2 involved a combination of SqCC and neuroendocrine carcinoma. Immunohistochemically the latter was positive for synaptophysin and neural cell adhesion molecule (NCAM). Case 3 involved a combination of SDC and epithelial-myoepithelial carcinoma (EMC). Immunohistochemically, the former was positive for GCDFP-15 and AR, whereas the inner cells of the latter were positive for cytokeratin 7, and the outer cells of the latter were positive for actin. Because of the transitional zone between SDC and EMC, it was speculated that high-grade SDC arose from low-grade EMC.

Mucoacinar Carcinoma: A Rare Variant of Mucoepidermoid Carcinoma

Mucoepidermoid carcinoma (MEC) is generally characterized by an admixture of mucous, epidermoid and intermediate type cells. Numerous variants morphologies are described and defined by stromal and/or cytoplasmic tinctorial characteristics. We now report 11 cases of MEC with serous acinar differentiation, reflecting a distal intercalated duct/acinar phenotype, which we designate as mucoacinar carcinomas. Seven patients were female while 4 were male with a mean age of 55 years (range: 21 to 72 y). Ten cases were from the parotid while 1 was from the submandibular gland. Mean size of the tumors was 1.8 cm (range: 0.7 to 4.5 cm). Three cases were low grade, 7 were intermediate grade, and 1 was high grade. Low to intermediate grade cases demonstrated prominent clear to vacuolated cells with focal serous acinar differentiation. The high-grade case showed a distinctive scattering of acinar cells interspersed between epidermoid cells. Periodic acid Schiff after diastase (9/9), SOX-10 (9/9), and DOG-1 (9/10) highlighted the acinar component. Six of 7 cases showed a focal acinar predominant NR4A3 expression. MAML2 fluorescence in situ hybridization was positive in all cases, in both acinar and mucoepidermoid components. Two cases tested by next generation sequencing showed standard CRTC1-MAML2 fusions. MSANTD3 and NR4A3 fluorescence in situ hybridization on the other hand were negative. Evidence thus suggests that mucoacinar carcinoma represents an acinar variant morphology in MEC, rather than a true MEC-acinic cell carcinoma hybrid, or collision tumor. The acinar differentiation, SOX-10, DOG-1, and even focal NR4A3 reactivity may thus be diagnostic pitfalls.

Salivary Duct Carcinoma of the Parotid Gland Originating from an Epithelial-Myoepithelial Carcinoma: Report of a Rare Case

Salivary duct carcinoma (SDC) is a high-grade carcinoma with poor prognosis, especially among various salivary carcinomas. In this study, we report a rare case of SDC of the parotid gland originating from an epithelial-myoepithelial carcinoma (EMC). A 71-year-old Japanese man presented with swelling of the right parotid region and a right facial nerve paralysis for 10 months. He underwent extended total parotidectomy and chemoradiotherapy after the surgery. Histologically, a major part of the tumor was an androgen receptor (AR)-positive, human epidermal growth factor receptor 2 (HER2)-positive, gross cystic disease fluid protein-15 (GCDFP-15)-positive SDC, with a focus of a typical EMC component at the periphery of the lesion. In the transitional area of the two components, inner ductal cells of double-layered ducts showed similar morphology and immunophenotype to SDC. These findings suggest that SDC originated from the inner ductal cells of EMC. Because the tumor included an EMC as a low-grade carcinoma and an SDC as a high-grade carcinoma, we can consider our case as a dedifferentiated carcinoma as well as a hybrid tumor.

An Unusual Hybrid Salivary Gland Tumor: Molecular Analysis Informs the Potential Pathogenesis of This Rare Neoplasm

Background

The presence of two or more tumor entities growing in adjacent locations within the salivary gland is very rare, and pathologic studies on such lesions are limited, particularly those with molecular information. Since the clinical history and imaging studies are usually nonspecific, accurate diagnosis and clinical management largely depend on a thorough histological examination.

Methods and Results

We describe a 71-year-old man with an unusual case of hybrid salivary gland tumor composed of mucoepidermoid carcinoma and basal cell adenoma. Molecular analysis revealed differing driver genetic alterations in each component.

Conclusions

Hybrid salivary gland tumors are rare, and their pathogenesis is controversial. The combination of mucoepidermoid carcinoma and basal cell adenoma has not been previously described. While malignant transformation of adenoma to carcinoma seems plausible, gene sequencing was more suggestive of their independent derivation. Key to appropriate surgical management is identifying the more aggressive component, ideally at the time of intraoperative consultation.

MYB Translocation Status in Salivary Gland Epithelial-Myoepithelial Carcinoma: Evaluation of Classic, Variant, and Hybrid Forms

Epithelial-myoepithelial carcinoma (EMC) is a malignant salivary gland neoplasm comprised of a biphasic arrangement of inner luminal ductal cells and outer myoepithelial cells. Adenoid cystic carcinoma (AdCC) is also a biphasic tumor comprised of ductal and myoepithelial cells, but these components tend to be arranged in a more cribriform pattern. The occurrence of "hybrid carcinomas" that show mixed patterns of EMC and AdCC raises questions about the relationship of these morphologically overlapping but clinically distinct tumors. AdCCs frequently harbor MYB-NFIB gene fusions. Mapping of EMCs (including hybrid forms with an AdCC component) for this fusion could help clarify the true nature of EMC as a distinct entity or simply as some variant form of AdCC. Twenty-nine cases of EMC were evaluated including 15 classic low-grade EMCs, 7 intermediate-grade EMCs, 2 EMCs with myoepithelial anaplasia, 1 EMC with high-grade transformation, and 4 hybrid EMCs with an AdCC component. Break apart fluorescence in situ hybridization for MYB was performed, as was MYB immunohistochemistry. For the hybrid carcinomas and those with high-grade transformation, the divergent tumor components were separately analyzed. A MYB translocation was identified in 5 of 28 (18%) tumors including 3 of 4 (75%) hybrid carcinomas and 2 of 7 (29%) intermediate-grade EMCs. For the positive hybrid carcinomas, the fusion was detected in both the EMC and AdCC components. The MYB fusion was not detected in any of the classic EMCs (0/15) or in any of the EMCs with myoepithelial anaplasia (0/2) or high-grade transformation (0/1). The fluorescence in situ hybridization assay was unsuccessful in 1 case. MYB immunostaining was seen in 5 of 5 fusion-positive cases, and also 9 of 23 fusion-negative tumors. Classic low-grade EMCs are genetically distinct from AdCCs in that they do not harbor MYB fusions. The presence of a MYB fusion in EMCs showing hybrid features of AdCC or exhibiting highly infiltrative growth points to a subset of these tumors that may well be true AdCCs masquerading as EMCs.

More than meets the eye

We report an extremely rare case of a hybrid tumour of the maxillary sinus. A 51-year-old man presented with a 6-week history of nasal congestion and epiphora. Radiological imaging demonstrated a maxillary sinus tumour, with extensive local invasion. Surgical excision included maxillectomy, left eye exenteration and free flap closure. Histology of the excised specimen showed a rare hybrid tumour containing adenoid cystic carcinoma, salivary duct carcinoma, epithelial-myoepithelial carcinoma and basal cell adenoma. Hybrid tumours are very rare tumour entities which are composed of at least two distinct tumour types. Each tumour entity conforms with a defined tumour type. The tumour entities of a hybrid tumour are not separated but have an identical origin within a definite topographical area. Diagnosis and appropriate management requires high index of suspicion, pathological endeavour to look for a more aggressive accompanying tumour and adequate oncological treatment according to the highest grade of tumour.

Salivary gland hybrid tumour revisited: could they represent high-grade transformation in a low-grade neoplasm?

Salivary gland hybrid tumour, first described in 1996, is a very rare neoplasm for which exact morphological criteria have not been universally agreed upon. In contrast, the concept of high-grade transformation (HGT) in salivary neoplasms has been widely accepted during the last decade, and the number of reported cases is rapidly increasing. A review of the literature revealed 38 cases of hybrid tumour reported in 22 publications. During approximately the same time period, well over 100 cases of HGT in salivary neoplasms have been reported. There are important histological similarities between hybrid tumours and salivary tumours with HGT. In the latter, containing one tumour component of low-grade malignancy and the other of high grade, the two tumour components are not entirely separated and appear to originate in the same area. Virtually, all cases reported as hybrid tumour had no clear lines of demarcation between the two tumour types. We are inclined to suggest that most of the 38 cases of hybrid tumours described in the literature would today better be called tumour with HGT rather than hybrid tumour. The relative proportion of the two components may vary, and the high-grade component is sometimes very small, which emphasises the importance of very generous sampling of the surgical specimen. The molecular genetic mechanisms responsible for HGT, including what used to be called hybrid tumour, remain largely unknown. Abnormalities of a few genes (including p53, C-MYC, cyclin D1, HER-2/neu) have been documented. As insufficient data exist on gene abnormalities in these lesions, conclusions as to whether or not they have a common origin and which mechanisms are involved in transformation cannot be drawn. Due to the small number of cases reported, many of which lack follow-up details; indicators of prognosis of hybrid tumours are not available, but their behaviour seems to be similar to that of tumours with HGT, i.e. an accelerated aggressive course. HGT of salivary gland neoplasms greatly influences macroscopic and microscopic evaluation of the specimen but also, given the high incidence of metastases and morbidity, carries significant treatment implications.

Fine needle aspiration of an unusual malignant mixed tumor in the parotid gland

OBJECTIVE

The use of fine needle aspiration (FNA) biopsy in the triage of salivary gland tumors has been well established. The sensitivity and specificity of FNA biopsy for tumor diagnosis is generally very good. However, the diagnosis can be challenging due to the limited amount of tissue sampled, the occasional overlapping tumor morphology, and the presence of a malignant counterpart of a benign tumor.

METHODS

FNA biopsy was performed with ultrasound guidance. Air-dried slides and alcohol-fixed slides were made for Diff-Quik staining and Papanicolaou staining, respectively. The syringes were rinsed and a cell block was prepared. The resected specimen was fixed in 10% formalin and processed by routine histology techniques.

RESULTS

We report a rare case of a salivary gland neoplasm with 2 distinct components: adenoid cystic carcinoma and pleomorphic adenoma. These 2 components are clearly identifiable in both cytological materials from fine needle aspiration and histological analysis of surgical resection.

CONCLUSION

Pleomorphic adenoma is the most common salivary gland tumor for patients in all age groups. The characteristic cytological feature is fibrillary extracellular matrix intermixed with epithelial cells. Malignant transformation occurs in 5% to 10% of cases. Rarely, pleomorphic adenoma exists as one component of a hybrid tumor. The surgical resection will be needed in those cases. The final diagnosis relies on the combination of the clinical information, histological findings and molecular study.

Lacrimal gland adenoid cystic carcinoma with high-grade transformation to myoepithelial carcinoma: report of a case and review of literature

Adenoid cystic carcinoma (AdCC) is the most frequent malignant neoplasm of the lacrimal glands. Like its salivary gland counterpart, lacrimal AdCC can rarely undergo high-grade transformation ("dedifferentiation"). We herein report the clinical, radiographic and microscopic findings of a lacrimal gland AdCC with high grade transformation, occurring in a 39-year-old female patient. In contrast to salivary gland AdCC with high-grade transformation, which usually shows a high grade component with "ductal" differentiation, in the case presented, the "dedifferentiated" component showed morphologic and immunohistochemical features of myoepithelial differentiation.

Hybrid carcinoma of the parotid gland: report of a case (epithelial-myoepithelial carcinoma and salivary duct carcinoma) and review of the literature

Hybrid tumors of salivary glands are rare neoplasms. We describe a case of a 74-year-old male with a hybrid carcinoma composed of epithelial-myoepithelial and salivary duct carcinomas of the right parotid gland. The presence of two components was verified by differential immunohistochemical staining. The tumor was surgically resected. There has been no evidence of recurrence to date. To our knowledge, this is the first report of a hybrid carcinoma composed of epithelial-myoepithelial and salivary duct carcinomas of the parotid gland in Japan.

Dedifferentiated epithelial-myoepithelial carcinoma of the parotid gland: a rare case report of immunohistochemical analysis and review of the literature

Dedifferentiation of salivary gland neoplasms is a rare event, unlike bone and soft part sarcomas, which was first described by Stanley et al. in 1988. An additional case of dedifferentiated epithelial-myoepithelial carcinoma (EMC) is reported here. The patient was a 70-year-old Japanese man who requested examination of the rapid growth of a mass in the right parotid region, which he had first noticed 25 years previously. Clinical examination showed an ill-circumscribed, 6.8 x 4.7 x 7.0-cm lesion. Histologically, most parts of the lesion were high-grade carcinoma (HGC) with sheetlike and nestlike growth of markedly atypical cells and comedonecrosis, whereas the minor part consisted of typical EMC. The outer clear cells of EMC were positive for alpha-smooth muscle actin (ASMA), p63, cytokeratin (CK) 14, and vimentin, and the inner ductal cells of EMC were positive for CKs and epithelial membrane antigen. HGC was negative for ASMA, CK14, and vimentin, but diffusely positive for p53 protein and cyclin D1. The Ki-67 labeling index of EMC was 11.5%, whereas that of HGC was 67.1%. These findings and a review of literature indicate that HGC arose from preexisting EMC, and this phenomenon is the dedifferentiation of EMC. Dedifferentiated EMC is extremely rare.

Epithelial-myoepithelial carcinoma: a review of the clinicopathologic spectrum and immunophenotypic characteristics in 61 tumors of the salivary glands and upper aerodigestive tract

To further define the clinicopathologic spectrum of epithelial-myoepithelial carcinoma (EMCa), we report the gross, histologic, and immunophenotypic characteristics of 61 tumors seen within a 30-year-period. The mean age at presentation was 60.9 years, with a female predominance (1.5:1). The most common sites were parotid (62.1%), sinonasal mucoserous glands (10.3%), palate (8.6%), and submandibular (8.6%). Most EMCas showed a characteristic nodular/multinodular growth pattern and classic biphasic tubular histology. However, new morphologies in EMCa such as ancient change (8.2%), "Verocay"-like change (3.3%), and sebaceous differentiation (13.1%) were noted. Specific histologic variants were dedifferentiated EMCa (3.3%), oncocytic EMCa (8.2%), EMCa ex pleomorphic adenoma (1.6%), double-clear EMCa (3.3%), and EMCa with myoepithelial anaplasia (3.3%). All cytokeratin cocktails selectively highlighted the epithelial component well. Of the myoepithelial markers, p63, smooth muscle actin and vimentin performed best. Bcl-2 and c-kit were frequently positive (66.7% and 69.2%, respectively). p53 was highly expressed only in 1 dedifferentiated EMCa. The recurrence rate was 36.3% (median disease-free survival 11.34 y), but death was rare with 5-year and 10-year disease-specific survivals of 93.5% and 81.8%, respectively. The most important univariate predictors of recurrence were margin status (log rank P=0.006), angiolymphatic invasion (P=0.002), tumor necrosis (P=0.004), and myoepithelial anaplasia (P=0.038). Thus, EMCa is generally a low-grade tumor with a broader morphologic spectrum than previously thought, with several key features predictive of recurrence. Immunohistochemistry can aid diagnosis by highlighting the biphasic nature of the tumor.

Salivary duct carcinoma in the sinonasal tract

Salivary duct carcinoma (SDC) is an uncommon malignant tumor, characterized by aggressive behavior and poor prognosis. SDC usually arises from ductal epithelium of the major salivary glands, and it is quite infrequent elsewhere. We present a rare case of a 73-year-old man with SDC, which is possibly originated from the paranasal sinuses or the lacrimal system. Microscopic evaluation revealed that the tumor cells, with pleomorphic nuclei and abundant eosinophilic cytoplasm, formed cell nests and duct-like structure. A cribriform growth pattern was also seen. Immunohistochemical staining was positive for cytokeratins (CAM 5.2 and 34betaE12), gross cystic disease fluid protein 15 (GCDFP-15), and androgen receptor protein, while p63 and involucrin were negative. The patient already had multiple metastasis of the tumor in the lung at diagnosis, and he could not undergo definitive surgical procedures, because of severe restrictive lung disease. Although SDC in the sinonasal tract is quite rare, SDC should be in the differential diagnosis in these regions, due to its aggressive behavior and poor prognosis.

A hybrid carcinoma of epithelial-myoepithelial carcinoma and adenoid cystic carcinoma in maxillary sinus

Hybrid carcinoma of the salivary gland is a very rare entity that has been described only in the parotid and palate. The occurrence of a hybrid carcinoma of maxillary sinus has not been reported. The diagnosis of hybrid carcinoma is important particularly when the components of tumor have different biologic behaviors. Diagnosis and treatment require a high index of suspicion, especially when the tumor is an epithelial-myoepithelial carcinoma, pathological effort to look for a more aggressive accompanying tumor, and proper oncologic treatment. We describe a case of 26-yr-old woman with a hybrid carcinoma composed of epithelial-myoepithelial carcinoma with an adenoid cystic carcinoma component (cribriform pattern) in the right maxillary sinus with a brief review of the relevant literature.

Defining the role of myoepithelium in salivary gland neoplasia

Neoplastic myoepithelium is considered to be the key cellular participant in morphogenetic processes responsible for the variable histologic appearances of many salivary gland tumors. Nevertheless, controversy still exists concerning its participation in some types of salivary gland neoplasms. This has been largely due to the difficulty in fully characterizing the wide spectrum of morphologic and immunophenotypic expressions of neoplastic myoepithelium compared with the normal counterpart. However, in recent years, our understanding regarding the phenotypic, immunophenotypic, ultrastructural, and biochemical properties of myoepithelium has advanced. Here we discuss the role of neoplastic myoepithelium in the scope of salivary gland neoplasia and present this information from a practical diagnostic standpoint.

Concomitant adenoma and hybrid carcinoma of salivary gland type arising in Bartholin's gland

We report a unique case of a salivary gland type of "hybrid carcinoma" arising within a Bartholin's gland adenoma. The tumor was characterized by large areas of an epithelial-myoepithelial carcinoma similar to that of the salivary gland with a peripheral infiltrative pattern of an adenoid cystic carcinoma (ACC).

Intercalated duct hyperplasia: possible relationship to epithelial-myoepithelial carcinoma and hybrid tumours of salivary gland

AIMS

The aims of this study were to ascertain the incidence of intercalated duct hyperplasia in association with cases of epithelial-myoepithelial carcinoma (EMC), and to explore a possible relationship between them and hybrid carcinomas of salivary glands.

METHODS AND RESULTS

Seven cases of EMC with sufficient surrounding non-tumour parotid were examined. Three cases contained foci of intercalated duct hyperplasia adjacent to the tumour. One of the cases was a hybrid tumour composed of EMC and mucoepidermoid carcinoma. The hyperplastic intercalated ducts formed multiple foci within the salivary parenchyma and were composed of bland, uniform ducts. Cytological atypia was not identified.

CONCLUSIONS

Intercalated duct hyperplasia may be a precursor lesion to EMC. Furthermore, it may also explain why EMC is frequently associated with other salivary gland carcinomas, so-called hybrid tumours, as well as sharing histological features with adenoid cystic carcinoma. Recognition of the latter is of particular importance because adenoid cystic carcinoma carries a poor prognosis.