Salivary Gland-type Tumors Research Articles

Pleomorphic adenoma presenting with a mediastinal mass.

Pleomorphic adenoma is the most common type of salivary gland tumor. Although it rarely affects the trachea and bronchus, it usually grows in the airway and presents as an endobronchial mass. We recently experienced a case of pleomorphic adenoma originating in the bronchus and growing outward into the mediastinum. We present this case with review of the computed tomography (CT) scan of the patient's chest, the endoscopic ultrasound (EUS), and the histopathology report.

Evaluation of c-kit protein (CD117) expression in common salivary gland neoplasms.

Background:Adenoid cystic carcinoma (AdCC) is a malignant salivary gland neoplasm with poor long-term prognosis. Differentiating between AdCC and other salivary gland neoplasms can be a diagnostic challenge, particularly in examining tissues obtained from small incisional biopsies.Aim:The aim of this study was to evaluate c-kit expression in four common benign and malignant salivary gland neoplasms.Materials and Methods:Immunohistochemical techniques were used to analyze the level of c-kit expression in normal salivary gland (n = 10) and four different types of salivary gland tumors: Pleomorphic adenoma (PA) (n = 17), AdCC (n = 9), polymorphous low-grade adenocarcinoma (PLGA) (n = 4) and mucoepidermoid carcinoma (MEC) (n = 6). Samples were immunostained using monoclonal antibody against c-kit.Results:The immunoreactivity for c-kit was found in all cases of AdCC, PLGA and MEC and majority of PAs. Positive reactivity was observed in more than 50% of the tumor cells of AdCC and less than 50% in PLGA. PA did not show strong immunostaining and c-kit was predominantly localized to the cell membrane. Furthermore, the difference in the expression of c-kit between the benign and malignant neoplasms was not statistically significant.Conclusions:CD117 expression itself cannot be used as a marker in differential diagnosis of salivary gland neoplasms. However, the percentage of the CD117 immunoreactive cells and the staining intensities appeared to be important factors in distinguishing AdCC from PLGA and PA.

Histogenesis of Fetal Parotid Gland

An analysis of the normal salivary gland structure permits a morphogenetic approach to an understanding of the variability in histologic types of salivary gland tumors. In the present study parotid gland specimens were collected from 25 aborted fetuses (8 male and 17 female) which were fixed in formalin. The fetuses were between 10weeks to 40 weeks of gestational age. The dissected specimens were preserved in 10% formalin and subjected to routine histological procedure for age related histogenesis and developmental anatomy. In present study we observed that major histogenesis occurred during the mid trimester that is around 24 wks of gestation. And at 40 wks of gestation acini are approaching adult appearance.

Establishment and characterization of METON myoepithelioma cell line derived from human palatal myoepithelioma: apical reference to the diverse differentiation potential

Myoepithelioma is an extremely rare condition that accounts for 1–1.5 % of salivary gland tumors. It was formerly regarded as a subtype of pleomorphic adenoma, in which myoepithelial structural components predominated, but was listed as a separate disease entity in the 1991 World Health Organization classification (Seifert in Histological typing of salivary gland tumours. Springer, Berlin, 1991). Its histology is highly varied and recurrence is frequent (El-Naggar et al. in J Larygol Otol 103:1192–1197, 1989), with cases of malignant transformation having been reported (Seifert in Histological typing of salivary gland tumours. Springer, Berlin, 1991; Barnes et al. in Pathology and Genetics of head and neck tumours. IARC Press, Lyon, 2005), making this a difficult tumor to control in many cases. This is thought to be due to the multiple differentiation potential of myoepithelial cells, but the details are unknown. There have been a number of reports of the establishment of cell lines (Shirasuna et al. Cancer. 45:297–305, 1980; Jaeger et al. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 84:663–667, 1997), but numerous points remain unclear. We established a myoepithelial cell line designated METON, and investigated its characteristics. METON consists of cells with two different morphologies: spindle-shaped cells and epithelial-like cells. Then. we also used single-cell cloning method to establish various subclones (epithelial-like, spindle-like, and mixed epithelial-like/spindle-like cell lines). Among these, pluripotency markers were expressed by the mixed epithelial-like/spindle-like cell lines. The newly established cell line expressing these pluripotency markers will be extremely useful for elucidating the diverse histologies of salivary gland tumors.

Opposing functions of PLAG1 in pleomorphic adenoma: a microarray analysis of PLAG1 transgenic mice

Over-expression of the proto-oncogene pleomorphic adenoma gene 1 (PLAG1) plays a crucial role in the formation of pleomorphic adenoma, which is the most common type of salivary gland tumor. To understand the molecular mechanisms governing PLAG1-mediated tumorigenesis, we used a microarray-based approach to identify PLAG1 target genes. We validated the expression of several genes, including Bax, Fas, p53, p21, p16, Cyclin D1, Egfr, Trail-R/DR5, c-Fos, c-myc and Igf2, by real-time RT-PCR or western blotting. Using luciferase reporter gene assays, we determined that the promoters of Bax, Fas, p53, TRAIL-R/DR5, and c-Fos were transactivated by PLAG1. PLAG1 not only activates genes that promote cell proliferation and tumor formation but also genes that inhibit these cellular processes. Therefore, we conclude that PLAG1 may play a dual role in tumor formation.

Myoepithelioma of the cerebellopontine angle: a previously not documented benign salivary gland-type neoplasm within the cranium

Myoepithelioma is a dimorphic neoplasm with contractile-epithelial phenotype, originally interpreted as deriving from, but not actually restricted to the salivary glands. As a novel addition to the list of exquisitely rare intracranial salivary gland-type tumors and tumor-like lesions, we report on an example of myoepithelioma encountered in the left cerebellopontine angle of a 32-year-old male. Clinically presenting with ataxia and dizziness, this extraaxial mass of 4 × 3.5 × 3 cm was surgically resected, and the patient is alive 6 years postoperatively. Histologically, the tumor exhibited a continuum ranging from compact fascicles of spindle cells to epithelial nests and trabeculae partitioned by hyalinized septa, while lacking tubular differentiation. Regardless of architectural variations, there was robust immunoexpression of S100 protein, smooth muscle actin, GFAP, cytokeratin, and vimentin. Cytologic atypia tended to be modest throughout, and the MIB1 labeling index averaged less than 1%. Fluorescent in situ hybridization indicated no rearrangement of the EWSR1 locus. We interpret these results to suggest that myoepithelioma of the posterior fossa - along with related salivary epithelial tumors in this ostensibly incongruous locale - may possibly represent analogous neoplasms to their orthotopic counterparts, ones arising within aberrant salivary anlagen. The presence of the latter lends itself to being mechanistically accounted for by either postulating placodal remnants in the wake of branchial arch development, or linking them to exocrine glandular nests within endodermal cysts. Alternatively, myoepithelioma at this site could be regarded as a non tissue-specific lesion similar to its relatives ubiquitously occurring in the soft parts.

ΔNp63 (p40) Distribution Inside Lung Cancer

ΔNp63 (henceforth simply p40) is a squamous/basal-type biomarker corresponding to nontransactivating (non-TA) isoforms of p63 gene. Its prospective relevance as driver biomarker in lung cancer has not yet been thoroughly investigated. In all, 72 adenocarcinomas (ADs), 27 squamous cell carcinomas (SQCs), 13 pleomorphic carcinomas (PLCs), 10 small-cell lung carcinomas (SCLCs), 5 large-cell neuroendocrine carcinomas (LCNECs), 5 adenosquamous carcinomas (ADSQCs), 3 large-cell carcinomas with basaloid features (B-LCC), 2 carcinoids, 2 carcinosarcomas (CS), 2 salivary-gland type tumors (SGTTs) of the lung, and 5 pleural malignant epithelioid mesotheliomas (MEMs) were prospectively diagnosed by morphology and verified by immunohistochemistry for p40, p63, and thyroid transcription factor 1 (TTF1). Histological scores (HS) were devised by multiplying the percentage of immunoreactive cells (0 to 100%) by immunostaining intensity (low = 1 vs strong = 2, according to internal controls). There was a nonrandom distribution of p40 across the diverse tumor groups and cell differentiation lineages, with p40-HS > 100 closely paralleling squamous or myoepithelial carcinomas (SQC, B-LCC, SQC-containing PLC, ADSQC with predominant SQC, SGTT), and p40-HS ≤ 10 pinpointing AD, AD-containing PLC, or CS and neuroendocrine (NE) tumors. At variance, p63-HS was significantly higher than p40 in AD (P < .0001) and NE tumors (P = .0156), with positive predictive value being 83% and 95% and overall accuracy being 95% and 99%, respectively. Also, TTF1 was shared by gland-differentiated and NE tumors. MEM cases were always negative for all biomarkers. The HS-guided assessment of p40 allowed an effective orientation among thoracic malignancies at the level of individual tumor patients thereby contributing to prospectively realize a driver, holistic approach to cancer characterization.

Diffuse Large B-Cell Lymphoma Arising in Warthin's Tumor: Case Study and Review of the Literature

Warthin's tumor is the second most common type of salivary gland tumor. Microscopically, Warthin's tumor displays a proliferative epithelial component and lymphoid stroma. Carcinomas arising from the epithelial component are well known, but malignant transformations of the lymphoid stroma are rare. When they do occur, they are most commonly B-cell type non-Hodgkin lymphomas. A 60-year-old male patient underwent surgical resection of a parotid mass. After superficial parotidectomy, microscopic examination indicated that the tumor was of epithelial components with basaloid and oncocytic columns of cells neighboring lymphoid components. In addition to the lymphoid follicles with distinct germinal centers, there were large, bizarre and extremely atypical neoplastic cells seen in the lymphoid component. Large neoplastic cells were diffusely CD20 and CD30 positive. The patient was diagnosed with "Warthin's tumor and diffuse large B-cell lymphoma with expression of CD30." The histopathologic and clinical features are discussed along with a review of the literature.

Perineural Involvement in Benign Mixed Tumor

Perineural invasion is a diagnostic clue of malignancy and may be indicative of a poor prognosis. Perineural involvement of a benign tumor is diagnostically confusing, however, and should not be considered a malignant feature. We report a case of benign mixed tumor of the salivary gland with two foci of perineural involvement. A 31-year-old man complained of a right parotid mass which had been present for three months. He had no relevant medical history. On physical examination, there was a movable, round mass that was not accompanied by tenderness or redness. Computed tomography revealed an ovoid mass in the deep lobe of the right parotid gland with strong, early, heterogeneous enhancement. There was no evidence of tumor invasion into the surrounding tissue. Right parotidectomy was carried out; the specimen was a well-demarcated, firm, ovoid mass (2.5×2.0×1.5 cm). Grossly, the mass was grayish-tan and solid, with multifocal hemorrhages. Microscopic findings were those of a typical benign mixed tumor of the salivary gland, consisting of mixed epithelial and myoepithelial cells with chondromyxoid stroma. No lymphovascular invasion was identified. Interestingly, two foci of small tumor cell nests were present around and within nerve twigs, which were located in the subcapsular space and the fibrous tumor capsule (Fig. 1). Five months after the operation, neither recurrence nor metastasis was evident on follow-up examination. Perineural invasion is an important pathologic feature of malignancy and is related to poor outcome. However, certain benign neoplasms and reactive conditions can reveal perineural involvement. Mixed tumor is the most common type of salivary gland tumors and, in most patients, is benign, except for rare secondary malignant transformation. Typical features of malignancy are infiltrative growth, nuclear pleomorphism, atypical mitosis, necrosis, and lymphovascular or perineural invasion. The presented case had perineural involvement of benign tumor cells; otherwise it exhibited characteristics of a benign mixed tumor. The important thing to consider here is the significance of perineural involvement in the biologic behavior of the tumor. Perineural involvement of benign lesions has been documented not only in the head and neck, but also in other sites. Benign mammary glandular deposits in nerves were first described by Ali and Epstein1 and other cases of benign tumor deposits of the breast, prostate, pancreas, gallbladder, endometrium, and skin have been reported in the literature. There have been no reported cases of benign mixed tumor of salivary gland with perineural involvement in Korea. Although the cause and mechanism of perineural involvement cannot be clearly defined, Skidmore et al.2 suggested a mechanical stress origin for perineural involvement of benign tumors, but theories regarding the mechanism of its development have yet to be proven. In the present case, fine needle aspiration was performed on the tumor a month prior to the operation, which may be a potential cause of mechanical stress. In conclusion, a histologically-benign mixed tumor of the salivary gland with perineural involvement should not be diagnosed as a malignant tumor without other evidence of malignancy.

1706P - Anti-Androgen Therapy for the Patients with Recurrent and/or Metastatic Salivary Duct Carcinoma Expressing Androgen Receptors: A Retrospective Study

ABSTRACT Background Salivary duct carcinoma (SDC) is one of the WHO classified histological types of salivary gland tumors (SGT) and consists of less than 10% among all the SGT. SDC is known as highly malignant with its aggressive clinical course, high rate of recurrence and metastasis and 2-3 years of median survival time. Up-front therapy is surgery, but treatment option is quite limited when it recurs and/or metastasis not being suitable for surgical resection. Androgen receptor (AR) is expressed in about 90% of SDC. Several reports suggest that AR would be a good candidate for treatment target for this entity. Patients and methods We conducted a retrospective analysis in patients with AR positive, recurrent and/or metastatic SDC treated anti-androgen therapy in our institution from January 1997 and April 2012. AR positivity was defined by immunohistochemistry (AR441, DAKO). Anti-androgen therapy was given as a single agent LH-RH analogue every four weeks until disease progression or intolerable adverse events. Responses to anti-androgen therapy were assessed according to RECIST. Results Eight patients were included. All were male. Median age was 57 years (range 40-76). Primary site was parotid gland in 7 and submandibular gland in 1. Initial clinical stage was II in 2, IVA in 5 and IVC in 1. All patients had received surgery for SDC prior to anti-androgen therapy. The patterns of relapse were locoregional recurrence in 4 and distant metastasis in all. Median number of cycles of anti-androgen therapy was 4 (range 2-10). No serious adverse event was seen. The best responses were PR in 2 and SD in 3, and median time of response duration was 4.6 months. After progression of anti-androgen therapy, all but one received chemotherapy included platinum compounds, taxanes and fluorouracil. Median overall survival time from receiving anti-androgen therapy was 22 months. Discussion and conclusion Anti-androgen therapy was well tolerated and demonstrated promising clinical activity for patients with recurrent and/or metastatic SDC. This might delay the start of chemotherapy and provide survival benefits, and this approach warrants further investigation. Disclosure All authors have declared no conflicts of interest.

Basal cell adenocarcinoma arising in salivary gland metaplasia of the breast: a novel salivary gland–type tumor developing in the breast

A variety of salivary gland-type lesions occur in the breast. Three cases of a novel mammary carcinoma arising in a background of salivary gland metaplasia and morphologically similar to basal cell adenocarcinoma of the salivary gland are presented. The clinical presentation, morphologic features, treatment, and follow-up of these cases are discussed.

Rare cancers of the head and neck area in Europe

The RARECARE project has proposed a different and more detailed grouping of cancers, based on localisation and histological type, in order to identify rare entities with clinical meaning. RARECARE gathered data on cancer patients diagnosed from 1978 to 2002 and archived in 76 population-based cancer registries, all of which had vital status information available up to at least 31st December 2003. This study provides incidence, prevalence and survival rates for rare head and neck epithelial (H&N) cancers.Among the rare H&N cancers, those of oral cavity had the highest annual crude incidence rate of 48 per million, followed by oropharynx and ‘major salivary glands and salivary gland type tumours’ (28 and 13 per million, respectively). Incidence rates of epithelial tumours of nasal cavities, nasopharynx, eye and adnexa and middle ears were all lower than 5 per million. The prevalence for all investigated entities was lower than 35 per 100,000. The 5-year relative survival rates ranged from 40% for epithelial cancer of oropharynx to 85% for epithelial cancer of eye and adnexa. Survival rates were lower for men and for patients aged ⩾65years. With few exceptions, the lowest and highest survival figures were observed for Eastern Europe and Northern Europe, respectively.According to the definition for rare tumours by RARECARE (incidence<6 per 100,000), as well as according to the definition for rare diseases by the European Commission (prevalence<50 per 100,000) the H&N cancers described in this paper should be considered rare and diagnosis and treatment of these cancers should therefore be centralised.

Pulmonary Salivary Gland–Type Tumors With Features of Malignant Mixed Tumor (Carcinoma Ex Pleomorphic Adenoma)

We report 5 cases of pulmonary salivary gland-type tumors with features of carcinoma ex pleomorphic adenoma. Patient ages ranged from 44 to 71 years (mean, 53.8 years); 4 patients were men and 1 was a woman. In all 5 cases, the lesions were associated with the bronchial system. None of the patients had a history of a head and neck salivary gland neoplasm. Histologically, the lesions were invasive tumors containing malignant myoepithelial elements and duct-like structures embedded in a benign chondromyxoid stroma. Areas reminiscent of residual pleomorphic adenoma were noted in 2 cases. Follow-up for 3 patients revealed that 2 died 22 and 54 months after diagnosis and 1 was alive 20 months after diagnosis. The cases are characterized by unique morphologic features that, coupled with their immunoprofile, suggest the possibility that these tumors represent carcinoma ex pleomorphic adenoma, an entity that has not been well documented in the bronchopulmonary system.

Primary pulmonary myoepithelial carcinoma

Primary salivary gland-type tumors of the lung are rare neoplasms. The pulmonary myoepithelial carcinoma belongs to this group. Since it was first described in 1998, we have identified only seven actual cases reported in the literature so far. We describe the case of a non-smoker 60-year-old Caucasian female, who was referred to our institution for the treatment of three peripheral nodules. Her medical history revealed that a wedge resection, for pulmonary myoepithelial carcinoma, was performed in another center 15 months previously. After resection of the current nodules, the histological findings showed three myoepithelial carcinomas of the lung. There was no vascular or lymphatic invasion. The hilar and mediastinal lymph nodes were negatives. The patient is doing well without any sign of recurrence. Herein we shall discuss the case of a primary pulmonary myoepithelial carcinoma in a female and propose a brief review of the literature.

The cytomorphologic spectrum of salivary gland type tumors in the lung and mediastinum: A report of 16 patients

In the lung and mediastinum, salivary gland type tumors (SGTTs) can occur as either primary tumors or metastases from tumors arising in the major or minor salivary glands. This study reviewed the cytology cases of SGTTs in the lung and mediastinum diagnosed over a six-year period at our institution. The specimens included a total of 22 exfoliative or aspiration cytology specimens identified in 16 patients. Two of the cases were primary tumors: adenoid cystic carcinoma (ACC) of the trachea and mucoepidermoid carcinoma (MEC) of the thymus. The remaining 20 tumors were metastases from the parotid, submandibular gland, tongue, nasal cavity, or soft palate. Eight of the 16 patients (50%) had a diagnosis of ACC, four (25%) had salivary duct carcinomas, two (12.5%) had MECs, one (6.25%) was a basaloid tumor, and one (6.25%) was polymorphous low grade adenocarcinoma. In our series, these SGTTs were more commonly metastatic in the lung or mediastinum (87.5% of the patients), and the most common histological subtype was ACC, followed by SDC. This study also illustrates the cytomorphologic features and diagnostic pitfalls of these unusual SGTTs.

TUMORS OF SALIVARY GLANDS

The glands are divided into major and minor salivary gland categories. The major salivary glands are the parotid, the submandibular, and the sublingual glands. The minor glands are dispersed throughout the upper aerodigestive submucosa. Salivary gland tumors are abnormal cells growing in the ducts that drain the salivary glands. Salivary glands tumors are uncommon and are subdivided into benign neoplasms, tumor-like conditions, and malignant neoplasms. They can be removed surgically or one can undergo radiation therapy for there cure. This article throws light on the types of salivary gland tumors, their signs and symptoms, treatment etc.

Risk of Parotid Malignant Tumors in Israel (1970–2006)

To the Editors: Major salivary gland cancers are rare and with few known risk factors. We have analyzed the incidence and epidemiologic features of major salivary gland cancer (ICD.C07–C091) using data from the Israel National Cancer Registry, 1970–2006. The annual incidence of major salivary gland cancer was 0.8 cases per 100,000. The most common subtype of salivary gland tumor was salivary gland carcinoma (60% of all cases) followed by squamous cell carcinoma (18%) and lymphoma (10%). Of 1924 cases (1039 men, 885 women), 60% were in the parotid gland, 7% in the submandibular gland, and fewer than 1% in the sublingual gland; the remaining 33% were recorded as overlapping or not otherwise specified (ICD.C 08.8, 08.9).1 Our results for sex, age, site, tumor type, and rate per year are similar to those reported in the literature. Comparing the parotid gland tumors with all other salivary gland locations, there were no important differences in risk by sex, age, or ethnicity. Trends for parotid gland cancers have seldom been reported, and have not been compared with other types of salivary gland tumors. The total number of parotid gland cancers in Israel increased 4-fold from 1970 to 2006 (from 16 to 64 cases per year), whereas other major salivary gland cancers remained stable (Fig. 1). The steepest increase occurred after 2001, with an average of 37 cases of parotid gland cancer annually before that date and 61 cases per year subsequently. The distribution of cases by age, sex, or tumor type did not change substantially during this time. The population of Israel increased 2.1-fold from 1970 to 2001, but only 1.1-fold from 2001 to 2006.2 Population growth could not, therefore, explain the increased number of parotid gland cancers.FIGURE.: For trend analyses, we added regression lines and calculated R 2 values. Parotid gland cancer: R 2 = 0.83; Submandibular gland cancer: R 2 = 0.36; Sublingual gland cancer: R 2 = 0.02.The proportion of major salivary gland cancers “not otherwise specified” declined from 36% before 2001 to 13% during 2001–2006. This shift may have contributed to changes over time in specific diagnoses. Nevertheless, even if we assume that all cases not-specified were parotid gland cancers, there remains a substantial increase of parotid gland cancers with time (72 cases per year after 2001 compared with 44 cases per year before). Published data have suggested possible etiologies for major salivary gland cancers, including exposure to radiation (therapeutic and diagnostic), aging, and other factors.3–5 The marked increase of parotid gland cancers in the last decade may reflect differences in an external risk factor specific to the parotid region. The INTERPHONE study6 has investigated parotid gland tumors and other tumors that originate in tissues most exposed and proximal to cellular phones. Israelis are heavy users of cellular phones, with a 6-fold increase in usage (by minutes) from 1997 to 2006.7,8 Investigators have previously suggested a potential association of parotid gland tumors with cell phones in an Israeli case-control study.7 Data on individual exposures to cell phones are not available in the registry data, and no causal association with parotid malignant tumors can be ascertained from these ecologic data. Further research is required to investigate the spectrum of possible etiological factors. Rakefet Czerninski Department of Oral Medicine Hebrew University-Hadassah School of Dental Medicine Jerusalem, Israel [email protected] Avi Zini Harold D. Sgan-Cohen Department of Community Dentistry Hadassah School of Dental Medicine Hebrew University Jerusalem, Israel

Epithelial-myoepithelial carcinoma ex pleomorphic adenoma in breast : An exotic rarity

Similarities in the embryogenesis of breast and salivary gland and the dual epithelial myoepithelial cell differentiation in both anatomical sites account for the occurrence of salivary gland-type neoplasm in the breast [1]. Pleomorphic adenoma (PA) is one such benign neoplasm that occurs in both salivary gland and breast. In salivary gland, malignant transformation of PA is a well-recognized, albeit relatively, uncommon event. Malignant transformation can take the form of superimposed adenocarcinoma or development of a malignant mixed tumour with dual epithelial and mesenchymal elements [2]. PA, also known as benign mixed tumour, accounts for 45 to 74% of all major and minor salivary gland tumours and has been reported in other, less common sites such as the paranasal sinuses, larynx, palate, nasal septum, skin and breast [3, 4], It occurs less frequently in the human breast. Since the first case report by Lecene [4] in 1906, 68 cases of PA of the human breast have been documented in the world literature [5]. Malignant PA has been reported to occur outside of the major salivary glands but its occurrence in breast is rare. There are only three such case reports in English language literature [1]. However, there is no case of epithelial-myoepithelial carcinoma on a PA of breast reported. We describe a case of epithelial-myoepithelial carcinoma ex pleomorphic adenoma of breast diagnosed and managed at our hospital.

The cell with a thousand faces: Detection of myoepithelial cells and their contributions in the cytological diagnosis of salivary gland tumors

Myoepithelial cells are an important component of salivary gland tumors and are partly responsible from the diverse histology of them. In this study, we focus on the myoepithelial cell differentiation by using cytological morphology in a various types of salivary gland tumors especially with regard to their contribution to the diagnosis. The relation of myoepithelial cells with stromal matrix and the associated epithelial cells were evaluated. Cytologic slides of one hundred and forty one benign and twenty malignant salivary gland tumors were examined for identification of morphologically different myoepithelial cells such as; spindle-stellate, polygonal-epitheloid, plasmacytoid, basal and clear types. The best examples of myoepithelial cells were detected in pleomorphic adenomas, in some monomorphic adenomas and in the adenoid cystic carcinoma cases. Most of the pleomorphic adenomas were composed more than one type of myoepithelial cells and epitheloid-spindle cell combination was frequent. Basal and clear cell types of myoepithelial cells closely resembled the epithelial cells and their identification was relatively difficult. Identification of myoepithelial cell types was easier when they were associated with stromal matrix material and stood as a secondary layer around tubule-forming epithelial cells. Myoepithelial cell components of various salivary gland tumors may be quite different and identification of myoepithelial cell types may pose difficulties. A confident cytologic identification of myoepithelial cells may be critical part of diagnosing salivary gland tumors.

Pulmonary adenocarcinoma with microcystic histology and intratumoral heterogeneity of EGFR gene polymorphism

To study the clinicopathological features of pulmonary adenocarcinomas with microcystic histology. Two cases of pulmonary adenocarcinoma exhibiting a unique microcystic growth pattern were analysed. The 20-mm tumour of a 59-year-old woman showed a predominantly complex microcystic architecture with a focal papillary configuration, whereas the 15-mm tumour of another 46-year-old woman displayed a solely microcystic growth pattern. The first tumour was found to have metastasized to lymph nodes at surgery and, 4 years later, to the chest wall. The second tumour did not metastasize or recur over a follow-up period of 12 years. The tumour cells were immunoreactive with thyroid transcription factor-1 (TTF-1), which helped to differentiate them from salivary gland-type tumours. No mutations of epidermal growth factor receptor (EGFR) or K-ras genes were detected. However, facilitated by laser microdissection, a Q787Q polymorphism was found in the microcystic component but not in the papillary component. To our knowledge, this is the first report to illustrate intratumoral heterogeneity of EGFR gene polymorphism among different growth patterns within the same tumour. Pulmonary microcystic adenocarcinoma has a variable clinical outcome. The microcystic tumour cells are immunoreactive with TTF-1 and may harbour polymorphisms of the EGFR gene.