Scholarly article on topic 'Clinicopathological study of 74 palatal pleomorphic adenomas'

Clinicopathological study of 74 palatal pleomorphic adenomas Academic research paper on "Biological sciences"

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{"clinicopathological feature" / "female predilection" / palate / "plasmacytoid myoepithelial cell" / "pleomorphic adenoma"}

Abstract of research paper on Biological sciences, author of scientific article — Yang-Che Wu, Yi-Ping Wang, Shih-Jung Cheng, Hsin-Ming Chen, Andy Sun, et al.

Background/purpose Pleomorphic adenoma (PA) is the most common salivary gland tumor and the palate is the most common intraoral site for PA. This study aimed to present the clinicopathological features of a series of 74 palatal PAs. Methods Seventy-four palatal PAs were collected from 1993 to 2009. The clinical and histopathological features of these 74 PAs were reviewed and analyzed. Results The 74 palatal PA patients showed a marked female predilection (49:25, ∼2:1) and were nearly evenly distributed from the 3rd to 8th decades of life with a mean age of 47 years. All palatal PAs were treated by wide surgical excision and recurrence was noted in one PA. Histopathologically, there were 47 classic and 27 cellular PAs. Of the 74 PAs, 12 were completely encapsulated, 40 partially encapsulated, and 22 nonencapsulated. The duct-like structures and myxoid stroma were more or less found in every palatal PA. Plasmacytoid myoepithelial cell, clear cell, squamous epithelial nest, keratin pearl, hyalinized stroma, osteoid area, and chondroid area were found in 50, 19, 29, 19, 49, eight, and six PAs, respectively. Conclusion We conclude that the palatal PA patients show a prominent female predilection (2:1) and are nearly evenly distributed from 20 years to 79 years of age. Plasmacytoid myoepithelial cell is the most characteristic type of tumor cell in PAs. Wide surgical excision is treatment of choice for PAs. Although ∼84% of palatal PAs are partially or nonencapsulated, recurrence of the lesion is rarely encountered after total surgical removal of the tumors.

Academic research paper on topic "Clinicopathological study of 74 palatal pleomorphic adenomas"

Journal of the Formosan Medical Association (2016) 115, 25-30

Available online at www.sciencedirect.com

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journal homepage: www.jfma-online.com

ORIGINAL ARTICLE

Clinicopathological study of 74 palatal pleomorphic adenomas

Yang-Che Wu, Yi-Ping Wang, Shih-Jung Cheng, Hsin-Ming Chen, Andy Sun, Julia Yu-Fong Chang*

CrossMark

a Graduate Institute of Oral Biology and Graduate Institute of Clinical Dentistry, School of Dentistry, National Taiwan University, Taipei, Taiwan

b Department of Dentistry, National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei, Taiwan

Received 12 September 2015; received in revised form 16 September 2015; accepted 18 September 2015

KEYWORDS

clinicopathological

feature; female predilection; palate; plasmacytoid

myoepithelial cell; pleomorphic adenoma

Background/purpose: Pleomorphic adenoma (PA) is the most common salivary gland tumor and the palate is the most common intraoral site for PA. This study aimed to present the clinicopathological features of a series of 74 palatal PAs.

Methods: Seventy-four palatal PAs were collected from 1993 to 2009. The clinical and histo-pathological features of these 74 PAs were reviewed and analyzed.

Results: The 74 palatal PA patients showed a marked female predilection (49:25, ~2:1) and were nearly evenly distributed from the 3rd to 8th decades of life with a mean age of 47 years. All palatal PAs were treated by wide surgical excision and recurrence was noted in one PA. His-topathologically, there were 47 classic and 27 cellular PAs. Of the 74 PAs, 12 were completely encapsulated, 40 partially encapsulated, and 22 nonencapsulated. The duct-like structures and myxoid stroma were more or less found in every palatal PA. Plasmacytoid myoepithelial cell, clear cell, squamous epithelial nest, keratin pearl, hyalinized stroma, osteoid area, and chondroid area were found in 50, 19, 29, 19, 49, eight, and six PAs, respectively. Conclusion: We conclude that the palatal PA patients show a prominent female predilection (2:1) and are nearly evenly distributed from 20 years to 79 years of age. Plasmacytoid myoepithelial cell is the most characteristic type of tumor cell in PAs. Wide surgical excision is treatment of choice for PAs. Although ~84% of palatal PAs are partially or nonencapsulated, recurrence of the lesion is rarely encountered after total surgical removal of the tumors.

Copyright © 2015, Formosan Medical Association. Published by Elsevier Taiwan LLC. All rights reserved.

Conflicts of interest: The authors have no conflicts of interest relevant to this article.

* Corresponding author. Department of Dentistry, National Taiwan University Hospital, 1 Chang-Te Street, Taipei 10048, Taiwan. E-mail address: jyfchang@ntu.edu.tw (J.Y.-F. Chang).

http://dx.doi.org/10.10167j.jfma.2015.09.008

0929-6646/Copyright © 2015, Formosan Medical Association. Published by Elsevier Taiwan LLC. All rights reserved.

Introduction

In humans, there are three pairs of major salivary glands including parotid, submandibular, and sublingual glands and 600—1000 minor salivary glands located mainly in the sub-mucosa of oral mucosae except the gingiva and anterior hard palate.1 The minor salivary glands include labial, buccal, glossopalatine, palatine, anterior lingual (glands of Blandin and Nuhn), posterior lingual mucous, and posterior lingual serous (von Ebner's glands) glands.1 The pleomorphic adenoma (PA) is the most common benign tumor in both major and minor salivary glands.2—6 The palate is the most common intraoral site for PA.3—6 Therefore, it desired to study the clinicopathological features of the palatal PAs.

In this study, 74 palatal PAs were retrieved from the files of Department of Pathology, National Taiwan University Hospital (NTUH), Taipei, Taiwan from 1993 to 2009. The clinical and histopathological features of these 74 PAs were reviewed, analyzed, and compared with those reported in previous studies.

Table 1 Demographic and clinicopathological parameters of 74 patients with palatal pleomorphic adenomas.

Methods

The study group included 74 palatal PAs retrieved from the files of Department of Pathology, NTUH from January 1993 to December 2009. All lesions > 1 cm in greatest diameter and suspected of being palatal PAs received an incisional biopsy. The whole lesion was then excised after the histo-pathological diagnosis was confirmed. If the tumors were < 1 cm in greatest diameter, they were surgically excised without doing the incisional biopsy in the beginning. The histopathological diagnosis of the lesion was mainly based on an examination of hematoxylin and eosin-stained tissue sections. Immunohistochemical staining was performed to identify the specific cells if needed.

The patients' data on age, sex, tumor size, treatment, and recurrence were obtained by reviewing the dental and medical charts. The excised specimens were fixed in 10% neutral formalin for at least 24 hours, dehydrated in graded alcohol, and then embedded in paraffin. If bony fragments were included, decalcification was also performed. The paraffin-embedded tissue blocks were cut in series sections of 5 mm, which were then stained with hematoxylin and eosin and examined by light microscopy.

The PA could be classified into myxoid, classic, and cellular types depending on the amount of stroma and the proportion of cellular components. The myxoid PA had myxoid stroma > 80% of the tumor, the classic PA was composed of some duct-like structures and myoepithelial cells within a myxomatous and hyalinized stroma, and the cellular PA was predominantly cellular with little amount of stromal tissue.7—9 We also assessed the encapsulation of the PAs to see whether they were completely encapsulated, partially encapsulated, or nonencapsulated. In addition, the presence of duct-like structure, plasmacytoid myoepithelial cell, clear cell, squamous epithelial nest, keratin pearl, myxoid stroma, hyalinized stroma, osteoid area, and chondroid area in PAs was searched and recorded.

Results

During the period from January 1993 to December 2009, 133 palatal minor salivary gland tumors were diagnosed in the Department of Pathology, NTUH. Of the 133 cases, 78

Figure 1 Clinical photographs of pleomorphic adenoma (PA). (A) A smooth-surfaced and dome-shaped PA at the right posterior lateral aspect of the palate. (B) A smooth-surfaced and dome-shaped PA at the left posterior lateral aspect of the palate.

Clinicopathological parameters

Pleomorphic adenomas (n = 74)

Sex Female Male

Female-to-male ratio Age (y) Mean age (range) 0—9 10—19 20—29 30—39 40—49 50—59 60—69 70—79 80—89 Type Myxoid

Osteoid area Chondronoid area

49 (66) 25 (34) 2:1

47 (11-83) 0(0) 6(8) 8 (11) 11 (15) 16 (22) 11 (15) 10 (13) 9(12) 3 (4)

Classic 47 (64)

Cellular 27 (36)

Capsule

Completely encapsulated 12 (16)

Partially encapsulated 40 (54)

Nonencapsulated 22 (30)

Component

Duct-like structure 74 (100)

Plasmacytoid cell 50 (68)

Clear cell 19 (26)

Squamous epithelial nest 29 (39)

Keratin pearl 19 (26)

Myxoid stroma 74 (100)

Hyalinized stroma 49 (66)

8 (11) 6 (8)

Data are presented as n (%) unless otherwise indicated.

Figure 2 Histopathological microphotographs of pleomorphic adenoma (PA). (A) A classic PA composed of duct-like structures in a myxomatous stroma. (B) A cellular PA made up of aggregates of plasmacytoid myoepithelial cells and a few duct-like structures lined by inner ductal cells and outer clear myoepithelial cells in a little hyalinized stroma. (C) A classic PA encapsulated by a thin layer of dense fibrous capsule. (D) A PA showing a sheet of characteristic plasmacytoid myoepithelial cells. (E) A PA exhibiting a few duct-like structures and many clear myoepithelial cells. (F) A PA with nests of squamous epithelia showing prominent intercellular bridges. (G) Several keratin pearls in a classic PA. (H) Nests of myoepithelial cells in a dense hyalinized stroma. (I) A PA showing osteoid structures with osteocyte-like cells in the lacunae. (J) A PA showing chondroid area with none or vacuolated chondrocytes in the lacunae. Hematoxylin and eosin stain; original magnification: A, B, D, E, H, I, and J, 20x; C, 4x; F and G, 10x.

(58.6%) were benign and 55 (41.4%) were malignant tumors. Only two types of benign salivary gland tumors, PA (74 cases, 55.6%) and myoepithelioma (4 cases, 3.0%), were found.10 Because PA was the most commonly occurring minor salivary gland tumor in the palate, this study concentrated on the presentation of clinicopathological features of 74 palatal PAs.

Palatal PA patients showed a marked female predominance with a female-to-male ratio of 49:25 (~2:1). The palatal PA patients were distributed in a wide age range from the 3rd to 8th decades with a peak incidence being in the 5th decade of life (22%). The mean age of palatal PA patients was 47 (range, 11—83) years (Table 1). All the 74 PAs were located in the posterior lateral aspect of the palate and presented as smooth-surfaced and dome-shaped swellings or masses clinically (Figure 1). Trauma-induced focal surface ulceration was noted in two PAs. The mean greatest diameter of 74 palatal PAs was 1.9 ± 0.9 cm (range, 1—4 cm). Thirteen PAs (17.6%) < 1 cm in greatest diameter were treated by excisional biopsy without initial incisional biopsy. The remaining 61 PAs (82.4%) were treated by wide surgical excision after incisional biopsy. Useful follow-up information was obtained for 38 PA patients (51.4%), local recurrence of the lesion was found in one PA after a follow-up period ranging from 5.8 years to 21.3 years.

Histopathologically, there were 47 classic (Figure 2A) and 27 cellular PAs (Figure 2B). There was no myxoid-typed PA in this study. Of the 74 palatal PAs, 12 were completely encapsulated (Figure 2C), 40 partially encapsulated, and 22 nonencapsulated. Duct-like structures and myxoid stroma were more or less found in every PA. Plasmacytoid myoe-pithelial cell (Figure 2D), clear cell (Figure 2E), squamous epithelial nest (Figure 2F), keratin pearl (Figure 2G), hya-linized stroma (Figure 2H), osteoid area (Figure 2I), and chondroid area (Figure 2J) were found in 50, 19, 29, 19, 49, eight, and six PAs, respectively.

Discussion

It is of no doubt that PA is the most common benign minor salivary gland tumor in the palate. Among all palatal minor salivary gland tumors, the frequency of the benign neoplasm ranges from 53% to 58%. Most of them are PAs, accounting for 39.8—51.9% of all palatal minor salivary gland tumors.2-6 PAs constitute 40—70% of all minor salivary gland tumors.4—66,11,12 In our previous study, PAs accounted for 55.6% of 133 benign and malignant minor salivary gland tumors of the palate.10 For the intraoral regions, the palate is the most common site for minor salivary gland tumors (42—54% of all cases), followed by the lips (21—25% of all cases) and the buccal mucosa (11—15% of all cases).3—6

PAs of all salivary glands show a female predominance with a female-to-male ratio of 1.9:1.4 Friedrich et al13 examined 94 PAs of all salivary glands and found that the parotid PAs occur more often in women (n = 45) than in men (n = 28) with a female-to-male ratio of 1.6:1. Sten-nert et al9 also demonstrated a slight female preponderance with a female-to-male ratio of 1.3:1 for 100 parotid

PAs. Our palatal PA patients showed a marked female predilection with a female-to-male ratio of 2:1. Becelli et al14 also found a significant female predilection for 11 patients with palatal PAs. Jorge et al15 also demonstrated that four out of five patients with juvenile intraoral PAs were female. However, Kuo et al7 examined 37 patients with PAs of extra-major salivary glands and discovered that 22 were male and 15 female, with a male-to-female ratio of 1.5:1. In addition, Chau and Radden16 also showed a slight male predilection (1:0.8) for 53 intraoral PAs.

Regarding the histological types of PAs, the myxoid, classic, and cellular PAs were found in 0, 33, and four of 37 PAs of extra-major salivary glands7; in two, five, and 19 PAs of minor salivary glands8; in 51, 14, and 35 of 100 PAs of the parotid glands9; and in zero, 47, and 27 of 74 palatal PAs in the present study, respectively. These findings suggest that there are more myxoid PAs in parotid glands than in minor salivary glands.

Stennert et al9 studied 100 parotid PAs and discovered that 97 had focally very thin capsule, 46 had focal absence of encapsulation, and 28 had pseudopodia projecting into the surrounding tissue or satellite nodules outside the capsule. Margaritescu et al17 studied 103 PAs of both major and minor salivary glands and found that 53 of 77 PAs of parotid gland and 10 of 16 PAs of submandibular gland were completely encapsulated. Moreover, 24 parotid PAs, six submandibular PAs, and two sublingual PAs were partially encapsulated. In addition, all the eight intraoral PAs were nonencapsulated.17 Chau and Radden16 examined 53 intraoral PAs and demonstrated that 12 (23%) were encapsulated, 31 (59%) partially encapsulated, five (9%) nonen-capsulated, and five (9%) indeterminate. Of our 74 palatal PAs, 12 (16%) were completely encapsulated, 40 (54%) partially encapsulated, and 22 (30%) nonencapsulated. The results of the aforementioned studies indicate that the majority (68—100%) of PAs of intraoral minor salivary glands are either partially encapsulated or nonencapsulated. Furthermore, although a relatively high proportion of PAs of major salivary glands are encapsulated, focally very thin capsule, focal absence of encapsulation, and pseudopodia projecting into the surrounding tissue or satellite nodules outside the capsule are not uncommonly found in PAs of major salivary glands.

Histologically, PA contains both epithelial and mesen-chymal (or stromal) components. The epithelial component may appear as ducts, tubules, strands, trabeculae, and solid sheets. The ducts of a PA are lined by inner duct-lining cells and outer myoepithelial cells. The presence of ducts or duct-like structures in a PA is the reason why PAs are called adenomas. Myoepithelial cells in a PA may appear as plasmacytoid, spindled, or clear cells. Squamous metaplasia, sometimes with the formation of keratin pearls, can be seen in both ducts and sheets of epithelial cells.18 The mesenchymal component may appear as myxoid and/or hyalinized connective tissue and occasionally as cartilage and/or bone. All these mesenchymal tissues are believed to be the result of metaplasia or actually products of the tumor myoepithelial cells.18 In this study, plasmacytoid cell, clear cell, squamous epithelial nest, keratin pearl, myxoid stroma, hyalinized stroma, osteoid area, and

chondroid area were found in 50, 19, 29, 19, 74, 49, eight, and six of 74 palatal PAs, respectively. Satpathy et al8 showed plasmacytoid cell, squamous epithelial nest, myx-oid stroma, hyalinized stroma, osteoid area, and chondroid area in 17, four, 19, one, two, and two of 26 PAs of minor salivary glands (including 24 palatal PAs). Moreover, Margaritescu et al17 demonstrated myxoid, fibro-hyaline, chondroid, and osteoid stroma in 103, 20, 45, and one, respectively, of 103 PAs of both major and minor salivary glands. The plasmacytoid cells are highly characteristic of a PA and almost never found in other salivary gland tumors.

Immunohistochemical staining is a useful technique to identify a specific cell type in tissues or tumors.19—31 For example, anti-CD1a and anti-S-100 protein immunostains can be used to recognize Langerhans cell in the lining epithelia of cyst or in tumors.19—26 When PA histological sections are immunostained, the inner ductal cells in the tubular or glandular structures are positive for cytokeratins 3, 6, 10, 11, 13, and 16, but the neoplastic myoepithelial cells are irregularly positive for cytokeratins 13, 14, and 16.18 The neoplastic myoepithelial cells coexpress pan-cytokeratin and vimentin and are variably positive for S-100 protein, calponin, CD10, glial fibrillary acidic protein, a-smooth muscle actin, and muscle-specific actin.18 Because neoplastic myoepithelial cells may have morphological diversity, sometimes they may need multiple immunostains to identify their cell origin.

In conclusion, the palatal PA patients show a prominent female predilection (2:1) and are nearly evenly distributed from 20 years to 79 years of age. Plasmacytoid myoepi-thelial cell is the most characteristic type of tumor cell in PAs. Wide surgical excision is the treatment of choice for PAs. Although ~84% of palatal PAs are partially- or nonencapsulated, recurrence of the lesion is rarely encountered after total surgical removal of the tumors.

References

1. Nanci A. Ten Cate's oral histology. Development, structure, and function. 8th ed. St Louis: Mosby Elsevier; 2013. p. 253—77.

2. Pires FR, Pringle GA, de Almeida OP, Chen SY. Intra-oral minor salivary gland tumors: a clinicopathological study of 546 cases. Oral Oncol 2007;43:463—70.

3. Yih WY, Kratochvil FJ, Stewart JC. Intraoral minor salivary gland neoplasms: review of 213 cases. Int J Oral Maxillofac Surg 2005;63:805—10.

4. Ellis GL, Auclair PL, Gnepp DR. Surgical pathology of the salivary glands. Philadelphia: WB Saunders; 1991.

5. Waldron CA, el-Mofty SK, Gnepp DR. Tumors of the intraoral minor salivary glands: a demographic and histologic study of 426 cases. Oral Surg Oral Med Oral Pathol 1988; 66: 323—33.

6. Eveson JW, Cawson RA. Salivary gland tumours. A review of 2410 cases with particular reference to histiological type, site, age and sex distribution. J Pathol 1985; 146: 51 —8.

7. Kuo YL, Tu TY, Chang CF, Li WY, Chang SY, Shiao AS, et al. Extra-major salivary gland pleomorphic adenoma of the head

and neck: a 10-year experience and review of the literature. Eur Arch Otorhinolaryngol 2011;268:1035—40.

8. Satpathy Y, Spadigam AE, Dhupar A, Syed S. Epithelial and stromal patterns of pleomorphic adenoma of minor salivary glands: a histopathological and histochemical study. J Oral Maxillofac Pathol 2014; 18:379—85.

9. Stennert E, Guntinas-Lichius O, Klussmann JP, Arnold G. His-topathology of pleomorphic adenoma in the parotid gland: a prospective unselected series of 100 cases. Laryngoscope 2001; 111:2195—200.

10. Wu YC. Clinicopathological study of palatal minor salivary gland tumors. Master thesis. Taipei: National Taiwan University School of Dentistry; 2013.

11. Spiro RH. Salivary neoplasms: overview of a 35-year experience with 2,807 patients. Head Neck Surg 1986;8:177—84.

12. Eneroth CM. Salivary gland tumors in the parotid gland, submandibular gland, and the palate region. Cancer 1971;27: 1415—8.

13. Friedrich RE, Li L, Knop J, Giese M, Schmelzle R. Pleomorphic adenoma of the salivary glands: analysis of 94 patients. Anticancer Res 2005;25:1703—5.

14. Becelli R, Frati R, Cerulli G, Perugini M, Frati A, Lannetti G. Pleomorphic adenoma of the minor salivary glands of the palate. J Exp Clin Cancer Res 2001;20:25—8.

15. Jorge J, Pires FR, Alves FA, Perez DE, Kowalski LP, Lopes MA, et al. Juvenile intraoral pleomorphic adenoma: report of five cases and review of the literature. Int J Oral Maxillofac Surg 2002;31:273—5.

16. Chau MN, Radden BG. A clinical-pathological study of 53 intraoral pleomorphic adenomas. Int J Oral Maxillofac Surg 1989; 18:158—62.

17. Margaritescu C, Raica M, Simionescu C, Mogoanta L, Surpa,eanu M, Jaubert F, et al. Tumoral stroma of salivary pleomorphic adenoma—histopathological, histochemical and immunohistochemical study. Rom J Morphol Embryol 2005;46: 211—23.

18. Eveson JW, Kusafuka K, Stenman G, Nagao T. Pleomorphic adenoma. In: Barnes L, Eveson JW, Reichart P, Sidransky D, editors. World Health Organization classification of tumours: pathology & genetics head and neck tumours. Lyon: IARC Press; 2005. p. 254—8.

19. Wu YC, Wang YP, Chang JYF, Chiang CP. Langerhans cells in lining epithelia of odontogenic cysts. J Formos Med Assoc 2013; 112:725—7.

20. Wu YC, Wang YP, Chang JYF, Chiang CP. Langerhans cells in lining epithelia of epidermoid cysts. J DentSci 2013;8:448—50.

21. Wu YH, Chang JYF, Chang HH, Chiang CP. Langerhans cells in the lining epithelium of dermoid cyst. J Formos Med Assoc 2016;115:57—8.

22. Chiang CT, Hu KY, Tsai CC. Central granular cell odontogenic tumor: the first reported case in oriental people and literature review. J Formos Med Assoc 2014;113:321—5.

23. Cheng SJ, Wang YP, Chen HM, Chiang CP. Central granular cell odontogenic tumor of the mandible. J Formos Med Assoc 2013; 112:583—5.

24. Lee JJ, Wei LY, Wu YC, Chiang CP. An early central granular cell odontogenic tumor arising from the dental follicle of an impacted mandibular third molar. J Formos Med Assoc 2014; 113:766—8.

25. Wu YC, Wang YP, Chang JYF, Chen HM, Sun A, Chiang CP. Langerhans cells in odontogenic epithelia of odontogenic fibromas. J Formos Med Assoc 2013; 112:756—60.

26. Wu YC, Chang JYF, Wang YP, Chiang CP. Langerhans cells in keratoacanthoma. J Formos Med Assoc 2015; 114:475—6.

27. Lee JJ, Wei LY, Wu YC, Chiang CP. Oral tongue melanoma. J Formos Med Assoc 2013;112:730-1.

28. Lin HP, Liu CJ, Chiang CP. Spindle cell lipoma of the tongue. J Formos Med Assoc 2015; 114:477-9.

29. Lu SY, Lin CF, Huang SC. Metastatic oral malignant melanoma transformed from pre-existing pigmented lesions in mandibular gingiva: report of an unusual case. J Dent Sci 2013;8:328-32.

30. Chen HM, Wu YC, Wei LY, Chiang CP. Metastatic hepatocellular carcinoma of the anterior palatal gingiva. J Dent Sci 2014;9: 202-4.

31. Lee JJ, Yang FY, Wu YC, Chen HM. Metastatic lung carcinoma to the lower anterior gingiva. J Formos Med Assoc 2014; 113: 978-80.