Multiple expression of tissue markers in mucoepidermoid carcinomas and acinic cell carcinomas of the salivary glands

Fine-Needle Aspiration Biopsy of Salivary Gland Lesions

CONTEXT

Fine-needle aspiration (FNA) is a well-established diagnostic approach for salivary gland lesions; however, lack of a standard system of terminology for classification of salivary gland neoplasms collected by FNA and the relatively high frequency of uncertainty of diagnosis are likely partly responsible for current confusion in the interpretation of these FNA samples.

OBJECTIVE

To propose a novel classification system for reporting salivary gland FNA samples and summarize recent progress in application of molecular and immunohistochemical markers in selected salivary gland neoplasms.

DATA SOURCES

Literature review and authors' personal practice experience.

CONCLUSIONS

The new classification system provides a more succinct, standardized interpretation of results and will ultimately assist in communication between clinicians, clinical decision making, and preoperative patient counseling. Impressive advances have been made in recent years in the understanding of molecular pathogenesis of salivary gland tumors. With the newly acquired diagnostic tools, significant improvement in diagnostic accuracy of salivary gland FNA can certainly be expected.

Salivary mucoepidermoid carcinoma revisited

Clinicopathological features, prognosis and therapeutic strategies for mucoepidermoid carcinoma originating in salivary and salivary-type glands of the head and neck are reviewed. We emphasise histopathological aspects, appraise the value of histochemistry, electron microscopy, immunohistochemistry and cytophotometry, and discuss histogenesis and characteristic gene translocations. We additionally consider possible diagnostic difficulties, problems related to histological grading and accuracy of existing literature, and areas of controversy or uncertainty which may benefit from further investigations.

P63 expression can be used in differential diagnosis of salivary gland acinic cell and mucoepidermoid carcinomas

Differentiation of salivary gland acinic cell carcinoma from mucoepidermoid carcinoma can be diagnostically challenging as both may have prominent mucin production. P63 is a p53 homologue required for limb and epidermal morphogenesis. It is expressed in basal and myoepithelial cells of normal salivary gland tissues. In this immunohistochemical study, we examined the expression of p63 in salivary gland acinic cell and mucoepidermoid carcinomas (MEC) and its use in differentiating these two entities. A search was performed and appropriate cases were selected from Lifespan Hospital System archives as well as the consult archives of one author (DRG). 31 salivary gland acinic cell carcinomas (ACC) and 24 MEC were examined for p63 expression by immunohistochemistry. The nuclear immunoreactivity was examined by both authors and was graded semi-quantitatively with negative being less than 10 % of cells staining. Positive staining was graded as follows: 10-25 % of tumor cells staining was weakly positive, 26-75 % of tumor cells staining was moderately positive, and 76-100 % of tumor cells staining was strongly positive. Negative nuclear staining of the tumor cells was seen in 30/31 (96 %) of salivary gland ACC while 1/31 (3 %) showed diffuse nuclear staining of the tumor cells. This latter case was later reclassified as mammary analogue secretory carcinoma following confirmatory molecular testing for the ETV6-NTRK3 fusion gene. Strong positive nuclear staining of the tumor cells was seen in 24 (100 %) of salivary gland MEC cases. P63 is an immunohistochemical stain that can potentially aid in differentiating unusual ACC with prominent mucin production from MEC of the salivary gland. According to this study, acinic cell carcinoma is always negative for p63 immunoreactivity while mucoepidermoid carcinoma is always positive.

Pleomorphic adenoma with extensive squamous metaplasia and keratin cyst formations in minor salivary gland: a case report

Pleomorphic adenoma (PA), the most common salivary gland tumor, accounts for 54 to 65% of all salivary gland neoplasias and 80% of the benign salivary gland tumors. It most frequently affects the parotid gland, followed by the submandibular and the minor salivary glands. Microscopically, mucous, sebaceous, oncocytic and squamous metaplasia, sometimes with the formation of keratin pearls, may be present, but the latter rarely results in the formation of extensive keratin-filled cysts lined by squamous epithelium. Extensive squamous metaplasia can be mistaken for malignancy, including mucoepidermoid carcinoma and squamous cell carcinoma. Here, we present an unusual case of PA with extensive squamous metaplasia and keratin cyst formations in a minor salivary gland, and discuss its microscopic features, including the immunohistochemical characteristics, and differential diagnosis of this uncommon presentation.

Clear cell entities of the head and neck: a selective review of clear cell tumors of the salivary glands

Clear cell changes may be observed in virtually any benign or malignant tumor of epithelial, mesenchymal, melanocytic and hematopoietic derivation not be attributed to variable etiologies. In general, benign and malignant clear cell neoplasms of the head and neck are rare. They may involve various regions and may be of diverse derivations, with only 1-2% of tumors of the salivary glands, jaws and oral mucosa are primarily or almost exclusively composed of clear cells (Maiorano et al., Semin Diagn Pathol 14:203-212, 1997). This review will selectively discuss the clinicopathological features of salivary gland tumors with clear cell changes, which, at times, may pose a diagnostic challenge and dilemma.

Unique case of pulmonary bronchial gland type tumor with broad spectrum of cell differentiation from the terminal duct-acinar unit to excretory duct

In the lung, acinic cell carcinoma (ACC) is a rare form of tumor. Reported herein is a unique bronchial gland-type tumor diagnosed as well-differentiated ACC that developed in the B9 bronchus of the left lung. Various immunohistochemical and histochemical staining partly satisfied the diagnosis of ACC. Moreover, this tumor contained various sizes of mucous cysts lined by columnar mucous cells, which produced abundant mucin positive for Alcian blue, which is usually present in mucoepidermoid carcinoma. Therefore, the present case is a unique tumor having a broad spectrum of cell differentiation from the terminal duct--acinar unit to the striated duct and excretory duct. This is the first case of unique bronchial gland-type tumor with mixed histological features of ACC and mucoepidermoid carcinoma.

Differential diagnosis of salivary acinic cell carcinoma and adenocarcinoma (NOS). A comparison of (immuno-)histochemical markers

A correct histologic differential diagnosis between salivary acinic cell carcinoma (ACC) and adenocarcinoma not otherwise specified (AC-NOS) is highly relevant because of the strikingly different biologic behavior and related therapeutical strategies. The distinction between both tumor types can be difficult because of an enormous variation in histologic appearance, with either type showing partially overlapping morphologic features. Owing to a lack of approved markers, the expression of PAS-staining, alpha-Amylase, alpha-1 Anti-trypsin, cytokeratin (CK)-subtypes 7/18 and Ki-67 was evaluated in 16 cases of ACC and 16 cases of AC-NOS. CK 7 is identified as the most reliable marker with strong positivity in AC-NOS, and complete or preponderant negativity in ACC. The characteristic membranous staining pattern of CK 18 in ACC, in contrast to a diffuse cytoplasmic pattern in AC-NOS, proved to be an additional valuable criterion. PAS and alpha-Amylase are only of little value when ACC is diagnosed, as many cases are only faintly positive or completely negative. The proliferation index (Ki-67) proved to be significantly higher in AC-NOS; however, the diagnostic usefulness is limited by a relevant overlap. In conclusion, we recommend CK 7 and 18 as the most valuable markers in cases with difficult differential diagnosis between ACC and AC-NOS.

Secretory carcinoma of the breast: a tumour analogous to salivary gland acinic cell carcinoma?

AIMS

Acinic cell-like breast carcinoma is a newly recognized entity, and few acinic cell-like breast carcinoma cases have been reported. All reported acinic cell-like breast carcinomas were counterparts of the solid type of acinic cell carcinoma of the salivary gland. We report here three cases of secretory breast carcinoma with acinic cell differentiation, and discuss the similarity between secretory breast carcinoma and acinic cell carcinoma of the salivary gland.

METHODS AND RESULTS

The cases were histologically identical to acinic cell carcinoma of the salivary gland: papillary-cystic type in case 1, a mixture of papillary-cystic, microcystic and follicular type in case 2, and microfollicular type in case 3. Immunohistochemically, the tumour cells were positive for salivary-type amylase, lysozyme, S100 protein and alpha 1-antitrypsin, and negative or less reactive for gross cystic disease fluid protein-15 and oestrogen receptor. All three cases did not reveal metastasis or recurrence.

CONCLUSIONS

These cases were typical of secretory breast carcinoma, and were clinically, histologically and immunohistochemically analogous to acinic cell carcinoma of the salivary gland. We emphasize that secretory breast carcinoma and acinic cell carcinoma of the salivary gland may be identical lesions.

Application of immunohistochemistry to the diagnosis of salivary gland tumors

A panel of antibodies composed of the cytokeratins (CKs), vimentin, and actin was applied to 114 minor salivary gland tumors to evaluate its diagnostic value. The results revealed that luminal cells of intercalated duct-like structures, such as those seen in pleomorphic adenoma, basal cell adenoma, adenoid cystic carcinoma, and epithelial-myoepithelial carcinoma, expressed CKs 7, 8, 14, and 19. The outer cells of these structures exhibited vimentin or vimentin plus muscle-specific actin, but rarely CK14, which is seen particularly in pleomorphic adenoma, in the tubular type of basal cell adenoma, and seldom in the tubular type of adenoid cystic carcinoma. Modified myoepithelial cells of pleomorphic adenoma and myoepithelioma exhibited a variable immunoprofile. CKs 7 and 8 were also observed in acinar cell adenocarcinoma and polymorphous low-grade adenocarcinoma with vimentin in the latter. CK13 was expressed only by canalicular adenoma and mucoepidermoid carcinoma cells. This study showed that the panel of antibodies employed is effective in distinguishing among salivary gland tumors.

Characterization of a newly established human acinic cell adenocarcinoma cell line (HACC) originating from the salivary gland: morphological features and role of various growth factors on the growth of the HACC cell line

Human acinic cell adenocarcinoma cell (HACC) line was established from the pleural effusion that contains metastatic tumor cells of acinic cell adenocarcinoma of papillary and microcystic type originating from the parotid gland. The HACC cells grew in an adherent monolayer with a doubling time of 66 h. Implanted tumor of SCID mice revealed similar histological findings to that of the primary tumor. The HACC cells produced mucin and expressed epithelial markers as well as alpha1-antitrypsin and lysozyme, whereas salivary peptide P-C was expressed in cultured HACC cells but not in the primary and implanted HACC cell tumors. S-100 protein was also expressed in both the primary tumor and HACC cell line. Neither amplification of common oncogenes nor expression of p53 was observed. The receptor for epidermal growth factor (EGF) was expressed, indicating EGF and transforming growth factor-alpha (TGF-alpha) enhanced the growth of the HACC line. Unexpectedly, tumor necrosis factor-a (TNF-alpha) also enhanced the growth of the HACC line significantly. However, there was no evidence of autocrine growth using these growth factors. In contrast, TGF-beta1 inhibited the growth of the HACC cell line through apoptosis. The HACC cell line has features similar to both acinar and intercalated ductal cells of the salivary gland. Epidermal growth factor, TGF-alpha and TNF-alpha are potential growth factors for the HACC cell line. The HACC cell line may be a good model for studying the biological behavior of salivary gland neoplasms.

Mucoepidermoid carcinoma of salivary gland origin: classification, clinical-pathological correlation, treatment results and long-term follow-up in 55 patients

Over a period of 30 years, 55 patients with mucoepidermoid carcinomas (MEC) of the salivary glands underwent surgical treatment. Reclassified TNM-stage (Hermanek et al., 1992) at the time of initial diagnosis varied (T0: 0, T1: 26, T2: 20, T3: 2, T4: 7; N0: 49, N1: 4, N2: 2; M0: 53, M1: 2). In 46% (n = 24), the history of symptoms ranged from 6 months to 2 years without any specificity of features. The therapy of choice is a radical ablative surgery of the primary tumour. The resection of the related lymphatic system has to be included in the therapeutic concept in patients suspected of having metastases of the regional lymph nodes. The prognosis is excellent in patients with a localized manifestation of the disease only. Our patients who died for reasons of tumour metastasis had all been classified as stage III or IV at the time initial diagnosis (n = 5). Distant metastases are rarely found even decades after surgical therapy (n = 1). This is why a long-term follow-up is recommended for patients with MEC of the salivary glands.

Central mucoepidermoid carcinoma. Report of a case and review of the literature

A case of central mucoepidermoid carcinoma (CMEC) occurring in a 68-year-old woman is reported. The tumor clinically appeared as a long-standing cortical swelling in the left angle of her mandible. As an intrabony lesion was radiologically evidenced, an odontogenic cyst was preoperatively diagnosed. Surgical curettage demonstrated a solid tumor the histological study of which allowed the final diagnosis. Immunohistochemical profile accorded with the patterns previously observed in salivary gland counterparts. Adjuvant radiotherapy was performed. Neither local recurrences nor metastases have been observed to date.

Distribution of tissue markers in acinic cell carcinomas of salivary gland

Eight cases of acinic cell carcinoma of the salivary glands were histologically reclassified and their immunohistochemical expression and distribution for various tissue antigens were examined. The epithelial elements were divided into tubuloglandular components, microcystic patterns and solid nests. The authors' results indicated the following: 1) The duct luminal cells of tubuloglandular components have distinct epithelial features with cytokeratin (KL 1), alpha 1-antichymotrypsin (alpha 1-ACT), transferrin, lactoferrin, IgA, and carcinoembryonic antigen (CEA) positivity. 2) The cyst-lining cells of microcystic pattern expressed immunophenotypes similar to those of the duct luminal cells. 3) The acinic cells in solid nests had positive results for KL 1, alpha 1-antitrypsin (alpha 1-AT), transferrin, lactoferrin and vasoactive intestinal polypeptide (VIP). 4) The clear cells in solid areas had positive results for KL 1, alpha 1-AT, transferrin and VIP. Both the clear cells and the neoplastic acinic cells showed a rather similar pattern of immunoreactivity. Therefore, the clear cells may transform from the neoplastic acinic cells. 5) Secretory products in tubuloglandular and microcystic patterns had positive results for alpha 1-ACT, lactoferrin, IgA and CEA. 6) The basement membrane-like material between the neoplastic islands has distinct positivity for alpha 1-AT. The result suggests that alpha 1-AT is a useful marker of basement membrane-like material.

The World Health Organization's Histological Classification of Salivary Gland Tumors. A commentary on the second edition

The second edition of the World Health Organization's Histological Classification of Salivary Gland Tumors is more extensive and detailed than the previous edition published 20 years ago. The new edition is based on data regarding newly described tumor entities and the behavior and prognosis of the previously classified tumors. The distinct morphologic features of monomorphic adenomas justify their separation for purposes of identification. Among the carcinomas, various types were distinguished for purposes of recognition, prognosis, and treatment. The term tumor was replaced by carcinoma in the following two entities: acinic cell carcinoma and mucoepidermoid carcinoma. The tumor-like lesions were described in more detail.

Histopathology of malignant salivary gland tumours

This report is based upon the Salivary Gland Register in Hamburg and on the second revised edition of the WHO Histological Typing of Salivary Gland Tumours. The group of malignant salivary gland tumours contains carcinomas, malignant non-epithelial tumours, malignant lymphomas and secondary tumours. The various carcinomas are classified in a continuous separate listing because the different types are distinguished not only by histopathology, but also by differences in prognosis and treatment. The term "tumour" is replaced by "carcinoma" in two entities: acinic cell carcinoma and mucoepidermoid carcinoma. New entities are: polymorphous low-grade adenocarcinoma, basal cell adenocarcinoma, salivary duct carcinoma and malignant myoepithelioma. Carcinoma in pleomorphic adenoma can be distinguished as non-invasive and invasive carcinoma, and carcinosarcoma. Malignant non-epithelial tumours are mostly malignant fibrous histiocytoma, malignant schwannoma and rhabdomyosarcoma. The large majority of malignant lymphomas are non-Hodgkin-lymphomas with high differentiation. Many lymphomas are associated with chronic immunosialadenitis (Sjögren's syndrome). Secondary tumours are mostly metastases from primary squamous cell carcinomas or from melanomas of the skin (head and neck area). Haematogeneous metastases are very rare (mainly from lung, kidney or breast).

Acinic cell carcinoma with primary presentation in an intraparotid lymph node

A rare case of a poorly-differentiated acinic cell carcinoma with primary presentation in a hyperplastic intraparotid lymph node, is reported. As the tumour mainly consisted of ductular and undifferentiated cells growing in solid cords, diagnosis was rendered difficult. Typical acinic cells were only rarely observed. In the multiple sections reviewed a single tumour nodulus occurred in salivary gland tissue outside the lymph node capsule. The possibility of a microscopic clinically occult primary acinic cell carcinoma that metastasized and presented primarily in an intraparotid lymph node, is mentioned. A multifocal origin in salivary tissue within and outside the intraglandular lymph node is another assumption, which is discussed. Differential diagnoses are mentioned and results of immuno- and histochemical studies are reported.

Immunoprofile of mucoepidermoid carcinomas of minor salivary glands

Because the data on the antigenic phenotype of mucoepidermoid carcinoma (MEC) are incomplete and somewhat disparate, 45 MECs were evaluated immunohistochemically for low- and high-molecular-weight keratins, vimentin, glial fibrillary acidic protein, smooth muscle actin, and S-100 protein. Tumors stained uniformly for keratins and, on occasion, focally for vimentin. Tumors were nonreactive with antibodies to glial fibrillary acidic protein and, with few exceptions, to muscle-specific actins and S-100 protein. Clear cell and papillary histologic variants were seen as potential diagnostic pitfalls. If used with hematoxylin-and-eosin-stained sections, limited potential is seen for this antibody panel in surgical pathology. Myoepithelial cell-associated antigens are expressed to a very limited extent in MECs.

WHO International Histological Classification of Tumours. Tentative Histological Classification of Salivary Gland Tumours

The principles of the proposed modified WHO Histological Typing of Salivary Gland Tumours are based on the following: 1) The classification of tumours is oriented to the routine work of the practicing surgical pathologists, those who do not see tumours of the salivary glands very often. The inclusion of rare, but clearly defined tumour entities should be helpful to surgical pathologists consulting with clinical specialists. 2) The different types of carcinomas must be distinguished not only by precise histopathological definitions, but also considering differences in prognosis and treatment. For example, the polymorphous low-grade adenocarcinoma and the epithelial-myoepithelial carcinoma are characterized by a relatively good prognosis in contrast to the salivary duct carcinoma. 3) Special points of discussion are: subclassification and grading of carcinomas (e.g. acinic cell carcinoma, mucoepidermoid carcinoma and adenoid cystic carcinoma), the classification of basal cell tumours (basal cell adenoma, basal cell carcinoma, solid type of adenoid cystic carcinoma), malignant tumours in pleomorphic adenomas and the differential diagnosis between primary tumours and metastases.

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.

Mucoepidermoid mammary carcinoma. Immunohistochemical and biochemical analyses of intermediate filaments

The histological features of mucoepidermoid mammary carcinomas (MMCs) are presented, and criteria for distinguishing these tumours from squamous epithelial metaplasia in other mammary carcinomas are considered. Immunohistochemical and gel-electrophoretic analyses of the intermediate-filament proteins in one MMC case revealed a complex pattern of cytokeratin polypeptide expression. The simple-epithelium-type cytokeratins 7, 8, 18, and 19 were detected mainly in nonsquamous (including mucinous) cells, while the stratified-epithelium-type cytokeratins 5, 6, 14, 16, and 17 were present in squamous cells. However, in both the nonsquamous and squamous regions of the tumour, cytokeratins of the "reverse" type were detected in individual cells. This pattern of single-cell heterogeneity with respect to cytokeratin polypeptide expression suggests that the mixed phenotype of this tumour is not caused by the clonal divergence of tumour cell types. Rather, histogenetically, a pluripotent stem cell with the ability to differentiate into squamous (epidermoid) or mucinous cells might be the starting-point of such a tumour and such differentiation processes may continue to occur during tumour growth. The present case also revealed that mucoepidermoid tumours are not necessarily of low malignancy; there are highly malignant forms with rapid metastasis.