Ultrastructural contributions to the study of morphological differentiation in malignant mixed (pleomorphic) tumors of salivary gland

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.

Primary Intracranial Manifestation of a Carcinosarcoma

Carcinosarcomas are tumors comprising part adenocarcinoma and part sarcoma; the presence of carcinosarcoma in the head-and-neck region is very rare. These tumors are typically highly aggressive (G3) and arise most frequently from the salivary gland. Here, we present a case report on a brain metastasis as the primary manifestation of a carcinosarcoma. Magnetic resonance imaging showed a tumor of the pineal region with infiltration of the brainstem and the corpus. The staging following the histopathological diagnosis revealed the origin of the tumor in the left parotid gland. We present an overview of the significance of published treatment strategies in carcinosarcoma.

Primary Carcinosarcoma of the Parotid Gland Mimicking as Parotid Abscess With Deep Neck Infection

Carcinosarcoma, true malignant mixed tumor, of the parotid is an extremely rare tumor. Pathologically, it is composed of malignant epithelial and malignant mesenchymal elements. The carcinosarcoma of the salivary glands comprised only 0.04% to 0.16% of all malignant salivary tumors with 65% occurring in the parotid gland. This tumor has an aggressive characteristic and is often regarded as a high-grade tumor with distant metastasis occurring in 54% of the patients. Patients usually present between 60 and 65 years of age and most series report no sex predominance. Radiologically, this tumor has a low attenuation center with a thick-enhancing wall and can be misdiagnosed deep neck infection in the parapharyngeal space. In this report, the authors report a patient of true malignant mixed tumor of the parotid gland mimicking as deep neck infection. Radiologic and histologic features including immunohistochemical results are discussed.

Mucoepidermoid Carcinoma Associated with Osteosarcoma in a True Malignant Mixed Tumor of the Submandibular Region

Introduction. True malignant mixed tumor, also known as carcinosarcoma, is a rare tumor of the salivary gland composed of both malignant epithelial and malignant mesenchymal elements. Frequently carcinosarcoma arises in the background of a preexisting pleomorphic adenoma; however, if no evidence of benign mixed tumor is present, the lesion is known as carcinosarcoma “de novo.” We reported the first case of true malignant mixed tumor of the submandibular gland composed of high grade mucoepidermoid carcinoma associated with osteosarcoma. Case Presentation. A 69-year-old Caucasian male came to our department complaining of the appearance of an asymptomatic left submandibular neoformation progressively increasing in size over 3 months. We opted for surgical treatment. Histological examination confirmed the diagnosis of carcinosarcoma with the coexistence of high grade mucoepidermoid carcinoma and osteosarcoma. Conclusion. To the best of our knowledge, in the true malignant mixed tumor of the submandibular gland, mucoepidermoid carcinoma associated with osteosarcoma has never been previously reported.

Primary carcinosarcoma of the parotid gland

Carcinosarcoma is a rare malignant ‘mixed’ tumour in the head and neck region. We present a case of carcinosarcoma in a long standing parotid lump and share our experience in the management of the disease together with a review of recent English literature on the subject.

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.

Carcinosarcoma of the parotid gland with epithelial-myoepithelial carcinoma and pleomorphic sarcoma components

We report a case of true malignant mixed tumour (carcinosarcoma) of the parotid gland with epithelial-myoepithelial carcinoma and pleomorphic sarcomatous components in a 68-year-old woman. The pleomorphic sarcomatous component behaved aggressively with lymph node and distant metastases. The biological behaviour of the individual components in a malignant mixed tumour makes it difficult to diagnose. We could find no previous report of epithelial-myoepithelial carcinoma as a component of a carcinosarcoma of the parotid.

Carcinosarcoma of the parotid gland: cytological, clinicopathological and immunohistochemical study of a case

Manifesting a putative origin from a pleomorphic adenoma, carcinosarcoma of the salivary gland is a heterologous neoplasm in which a sarcomatous and a carcinomatous component coexist. We present a parotid gland carcinosarcoma in a 77-year-old man with peculiar morphological findings. Fine-needle aspiration cytology allowed a preoperative diagnosis of poorly differentiated carcinoma. At histologic examination, the tumor showed biphasic differentiation with an epithelial component made up of well-differentiated keratinizing squamous carcinoma and ductal-type adenocarcinoma, and a mesenchymal component, revealing focal areas of osteosarcoma and myoepithelial malignant proliferation. Carcinosarcoma is a very rare malignant neoplasm, accounting for 0.16% of malignant salivary gland tumors: only 60 cases have been reported, some of which arose "de novo", i.e., without clinico-pathologic evidence of a pre- or co-existing pleomorphic adenoma.

Noninvasive and minimally invasive carcinoma ex mixed tumor: a clinicopathologic and ploidy study of 12 patients with major salivary tumors of low (or no?) malignant potential

We studied 12 histologically malignant salivary tumors that showed complete encapsulation or only limited microscopic invasion. Most cases were histologically characterized by atypical and mitotically active luminal cells forming dilated, angular, variably sized glands in the subcapsular region, varying proportions of nonluminal tumor cells, and a background of central fibrosed hyalinized stroma. The appearance is that of a low-grade carcinoma. Focal higher grade carcinoma was superimposed on this histologic data in three cases. Neither recurrences nor metastases were seen in 11 of 12 patients after surgical resection with a follow-up of 1.2 to 13 yrs (mean, 4.2 years). Ploidy studies were performed on the paraffin-embedded tissue in 11 cases and yielded results for 7 cases. Aneuploid cell populations were found in five tumors; two had normal diploid populations; and the ploidy results are not predictive of tumor behavior. This type of salivary gland tumor fits diagnostically within the category of noninvasive and minimally invasive carcinoma ex pleomorphic adenoma (also referred to as in situ and low-grade malignant mixed tumors), a class that requires additional awareness and precise recognition as it signifies a good prognosis after surgical resection.

Carcinosarcoma of salivary glands with unusual stromal components. Report of two cases and review of the literature

Carcinosarcomas are rare neoplasms that exhibit heterologous malignant epithelial and stromal components. We report two cases of salivary gland carcinosarcoma with immunohistochemical analysis and clinical follow-up that provide insights into the pathogenesis and behavior of these tumors. In one case, a 51-year-old black woman had a 15-year history of a hard, asymptomatic, infraauricular mass that recently had undergone rapid growth. The tumor showed adenocarcinoma and osteosarcoma. She died 9 months after diagnosis. In another case, a 78-year-old white woman had a large soft palate mass that had been present for several years and had recently caused dysphagia. The tumor showed adenocarcinoma and leiomyosarcoma. The patient is alive at 9 months follow-up. Although malignant epithelial and stromal components characterize carcinosarcomas, immunohistochemical studies suggest that both elements are derived from a common precursor cell, possibly of myoepithelial origin. These cases support this concept and perhaps suggest a spectrum of differentiation that this precursor cell may exhibit.

Fine-needle aspiration cytology of carcinosarcoma of the parotid gland: cytohistological and immunohistochemical findings

Carcinosarcoma or true malignant mixed tumor of salivary glands is a very rare neoplasm which shows malignant features of the epithelial and mesenchymal components. We hereby present cytological, pathological, and immunohistochemical findings of one such case, first examined by fine-needle aspiration cytology. The aspirate was cell-rich and consisted of large cell clusters which at low magnification showed an arrangement reminiscent of a jigsaw puzzle. An amorphous substance was observed in the middle of some of these clusters. There were also numerous dissociated cells which often displayed marked atypia. Histology showed a tumor with malignant epithelial and mesenchymal components. The carcinomatous areas consisted of cells arranged in solid nests or glandular structures. The sarcomatous areas showed osteosarcoma, low-grade chondrosarcoma, and undifferentiated components. On immunohistochemistry, the tumor coexpressed epithelial and mesenchymal markers. Cytokeratin, keratin, and epithelial membrane antigen were mainly localized to the carcinomatous portion, whereas vimentin and neuron-specific enolase were restricted to the sarcomatous areas. S-100 protein was positive in both. Our findings support previous views that this tumor may be related to pleomorphic adenoma.

Carcinosarcoma (malignant mixed tumor) of the parotid: report of a case with a pure rhabdomyosarcoma component

BACKGROUND

Carcinosarcoma or true malignant mixed tumor of the parotid gland is extremely rare, accounting for < 1% of all salivary gland malignancies.

METHODS

A 63-year-old woman presented with a 5-cm right parotid mass which was resected with a radical parotidectomy and infratemporal fossa dissection.

RESULTS

The tumor contained two distinctive histologic patterns, that of a poorly differentiated ductal carcinoma and a pleomorphic rhabdomyosarcoma. Additionally, a residual focus of pleomorphic adenoma was present peripherally. Immunohistochemical and electron microscopic studies confirmed the skeletal muscle differentiation.

CONCLUSIONS

The pattern of combined rhabdomyosarcoma and ductal carcinoma has not been previously reported and adds further evidence to the myoepithelial derivation of these tumors.

Pathology of the salivary glands: the contribution of electron microscopy

Electron microscopy has a limited role in the diagnosis of primary salivary gland tumors, although it can be helpful in metastatic lesions of possible salivary gland origin. The diversity of subtypes in salivary gland tumors, as well as the range of histomorphology within any one subtype, is unparalleled in any other human tumor. This and their relative infrequency causes diagnostic problems for pathologists. Ultrastructural techniques have been of major importance in determining the inter-relationship of these tumors for classification purposes, revealing the subtle variations in common cellular differentiation pathways, determining the organization of tumor cells, and displaying the importance of extracellular matrix materials in establishing diagnostic criteria for each of the many subtypes. Electron microscopy has also been valuable in non-neoplastic salivary gland disease and has an increasing role in experimental studies involving tissue from human and animal salivary parenchyma.

Nucleolar organizer regions in malignant salivary gland tumors

Proliferative activity of carcinomas arising from salivary glands was analyzed by enumeration of argyrophilic nucleolar organizer regions (AgNORs). The mean numbers of AgNORs in the various tumors were as follows: mucoepidermoid carcinoma, 2.20; acinic cell carcinoma, 2.51; adenoid cystic carcinoma (ACC), 2.57; carcinoma in pleomorphic adenoma, 1.00 (benign component) and 3.99 (cancer-bearing area); salivary duct carcinoma, 4.49; polymorphous low-grade adenocarcinoma, 3.37; sebaceous carcinoma, 2.57; oncocytic carcinoma, 4.63; adenocarcinoma, 4.53. Cells of most tumors showed heterogeneous activity within the same tumor. In mucoepidermoid carcinoma, the mucous cells had suppressed activity in comparison with the epidermoid cells and intermediate cells. In ACC, the activity of the tumor cells increased according to growth pattern in the order tubular, glandular and solid. In carcinoma in pleomorphic adenoma, vigorous proliferative activity was observed in the malignant component, whereas less active cells were seen in the myxoid or chondroid matrix. AgNOR staining was useful for distinguishing benign from malignant regions in carcinoma in pleomorphic adenoma. Our results suggest that mucoepidermoid carcinoma, acinic cell carcinoma and ACC, except for that with a solid growth pattern, may be considered as low-grade malignancies, whereas solid-type ACC, the cancer component in carcinoma in pleomorphic adenoma and some of the other carcinomas have high-grade malignant behavior.

Mixed tumor of salivary gland type arising in the bronchus

During bronchoscopy for atelectasis of the middle lobe, a 61-year-old man was found to have a polypoid mass obstructing the bronchus. Right middle and lower lobectomy disclosed a tumor growing into the lumen of the middle lobe bronchus. The histological features of the tumor were indistinguishable from those of the mixed tumor of the salivary gland. A review of the literature reveals only 7 cases of this extremely rare tumor.

Comparative investigation of c-erbB2/neu expression in head and neck tumors and mammary cancer

Normal tissues, primary tumors, and metastases of mammary and salivary glands and oral/laryngeal mucosa have been analyzed with Northern-blots employing 32P-labeled RNA probes for the expression of the neu oncogene. Neu oncogene expression of a mRNA species of 4.6 kilobases was found in all normal salivary (five) and mammary glands (four) as well as in two normal or inflamed samples of tongue mucosa. This expression was regarded as baseline activity of the neu gene for the respective tissues and was used as standard for the evaluation of benign and malignant tumors. None of 14 squamous cell carcinomas of the oral and laryngeal mucosa showed enhanced neu transcription level. Five fibroadenomas, one benign variant of phylloid tumor, one carcinosarcoma, and one of two proliferative fibrocystic diseases of the breast showed lacking or normal baseline expression of the neu oncogene, as did one monomorphous cystadenolymphoma of the parotid gland. In contrast, four parotid pleomorphic adenomas and one salivary gland adenocarcinoma showed enhanced neu expression. For mammary adenocarcinomas, increased neu oncogene expression concerned ten of 34 cases--all being variants of ductal carcinomas--and all metastases analyzed (six) deriving from three primaries. One adenoid cystic carcinoma also showed enhanced neu expression. Neu overexpression may reflect accidents of genomic reconstitutional events occurring regularly within the differentiation pathway of epithelial/myoepithelial cells. This assumption was supported by further immunohistochemical analysis which showed stainings of myoepithelial and myoepithelia-like cell populations in tumors, especially pleomorphic adenomas and adjacent normal-looking tissues.

Comparative histogenesis and morphogenesis of mucoepidermoid carcinoma and pleomorphic adenoma. An ultrastructural study

Current classifications of salivary gland tumors separate mucoepidermoid carcinoma from other neoplasms on the basis of a number of histological features, in particular the lack of participation of neoplastic myoepithelial cells. However, ultrastructural examination of low- and intermediate-grade mucoepidermoid carcinomas and pleomorphic adenomas reveals many common organizational and cellular features. Of prime importance is the relationship of intermediate cells to the luminal cells in mucoepidermoid carcinomas, which is remarkably similar to that seen between modified myoepithelial cells and luminal cells in pleomorphic adenomas. The results suggest that intermediate cells of mucoepidermoid carcinoma are the counterpart of the modified myoepithelial cells of pleomorphic adenoma. The generally accepted hypothesis that the former tumor develops from an excretory duct reserve cell, while the latter originates from an intercalated duct stem cell does not seem to be valid; pleomorphic adenoma and mucoepidermoid carcinoma appear to be closely related morphologically.

Ultrastructural and immunohistochemical observations of a true malignant mixed tumor (carcinosarcoma) of the tongue

True malignant mixed tumor (TMMT) of salivary glands, with both carcinomatous and sarcomatous components, is exceedingly rare. We offer a case of TMMT in a 79-yr-old man, which may represent the first report example of this unusual neoplasm arising in the tongue. The carcinomatous component was mainly of solid basaloid carcinoma with focal glandular differentiation, while the sarcomatous component was composed of pleomorphic elements such as chondrosarcoma, myxosarcoma and fibrosarcoma. Carcinoma cells at the periphery of solid nests occasionally merged into these sarcomatous elements. Immunohistochemically, basaloid carcinoma cells showed positive reaction for both low molecular weight cytokeratin and S-100 protein, whereas carcinoma cells lining ductal spaces were positive for a wide spectrum of keratin and EMA. The sarcomatous elements revealed the presence of vimentin and S-100 protein. Ultrastructurally, basal lamina-like material and/or mucoid precipitates often accumulated separating the tumor cells from each other singly or into a few cell group. Some sarcomatous cells assumed the myoepithelial features, such as the presence of microfilament bundles with dense bodies and pinocytotic vesicles along the cell periphery. These findings may indicate that TMMT shares a common histogenesis with pleomorphic adenoma.

Salivary gland myoepithelioma variants. Histological, ultrastructural, and immunocytological features

The histological and ultrastructural features of five major salivary gland tumours, which have little or no evidence of duct- or gland-type differentiation in routine sections, are described. Four of the cases have the tumour cells organized as narrow, anastomosing cords of cells separated by a myxoid and vascularized stroma; we have designated such lesions as reticular-type myoepitheliomas. The fifth case has a solid growth pattern and is largely composed of hyaline cells, that is, a plasmacytoid myoepithelioma. Ultrastructurally, one reticular myoepithelioma reveals myoepithelial cell differentiation with microfilament aggregates, while the other three examples are composed of modified myoepithelial cells displaying widened intercellular spaces, prominent synthesis of extracellular glycosaminoglycans, distinct basal lamina development, and obvious accumulations of cytoplasmic intermediate filaments. In electron micrographs, the modified myoepithelial cells of the plasmacytoid variant closely resemble the tumour cells in the reticular form. Three cases had expression of both glial fibrillary acid protein (GFAP) and vimentin, but only one of the myoepitheliomas contained muscle-specific actin. At least focally, each of the cases exhibited a considerable spectrum of cytokeratin filaments. Using double-labeled immunofluorescent microscopy of one reticular variant and the plasmacytoid myoepithelioma, there was individual tumour cell co-expression of GFAP and vimentin focally in the plasmacytoid myoepithelioma, but co-expression of cytokeratins 13, 16 and GFAP were not noted in either case. As expected, co-expression of high- and low-molecular weight cytokeratin filaments was widespread in both myoepitheliomas. Most described myoepitheliomas have a solid growth pattern and are composed of spindle and plasmacytoid cells, but based on cytological features and growth patterns in this series, it is apparent that polygonal-shaped cells with novel architecture can occur in myoepitheliomas. The results also indicate the close relationship between pleomorphic adenoma and such variants of myoepithelioma.