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Mucoepidermoid carcinoma

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Mucoepidermoid carcinoma

  1. 1. Mucoepidermoid carcinoma
  2. 2. Definition Mucoepidermoid carcinoma is a distinctive salivary gland malignancy composed of mucinous, intermediate (clear cell), and squamoid tumour cells forming cystic and solid patterns. WHO Classification of Head and Neck Tumours, 4ed, (2017) Or a malignant glandular epithelial neoplasm characterized by mucous, intermediate and epidermoid cells, with columnar, clear cell and oncocytoid features (Simpson, Skálová, Di Palma, & Leivo, 2014)
  3. 3. Epidemiology WHO Classification of Head and Neck Tumours, 4ed, (2017) It is a rare tumour that most commonly manifests as intraoral salivary gland carcinoma (in 37-53% of cases), with a slight female predilection. A wide patient age has been reported, with the mean age in the sixth decade of life occurs over a wide age distribution, and is the most common salivary gland with a peak incidence in he second decade
  4. 4. mucoepidermoid carcinoma is the most common malignant salivary gland tumour, representing approximately 10% of all salivary gland tumours and 25% of malignant lesions. Although most common in the parotid gland, mucoepidermoid carcinoma is frequently encountered in the oral cavity in the palate, cheeks, lips, tongue and retromolar region. Importantly, mucoepidermoid carcinoma is the most common salivary malignancy in children. Epidemiology
  5. 5. Aetiology MEC may develop secondary to radiation or chemotherapy during childhood, with a median latency period of 8 years
  6. 6. Localization The parotid is the most common site followed by the palate, submandibular gland, and other intraoral minor salivary gland sites The palate is the most common intraoral site, accounting for > 50% of intraoral Cases. carcinoma is frequently encountered in the oral cavity in the palate, cheeks, lips, tongue and retromolar region.
  7. 7. Clinical features The tumours are often asymptomatic, but may cause symptoms, depending on the site and histological grade. The clinical presentation varies depending on tumour size, and grade. Cystic intraoral can mimic a mucocoele. mucinou MEC may fluctuate in size due cyst rupture and may present as a mucin draining cutaneous fistula.
  8. 8. Cytology 1- Aspirtes of low-grade, mostly cystic lesions Shows: predominately mucus + macrophage + Occasional bland epithelial cells may be seen. 2- Aspirates of higher-grade lesions: more cellular, showing an admixture of epithelial cell types typical of the lesions + Cytological pleomorphism + mitotic activity + necrosis may be seen
  9. 9. Histopathology is characterized by variable components of squamoid, mucin- producing, and intermedia type cells. with a cystic and solid growth pattern. Keratinzation is rare but usually have Oncocytic, clear-cell and sclerosing variants. Mucicarmine stainng and periodic acid-Schiff (PAS) stain with diastase demonstrate intracytoplasmic staining in mucinous cells.
  10. 10. A low grade, extensively cystic mucoepidermoid carcinoma of the tongue, showing intermediate (arrow), mucous and clear cells in the cyst lining.
  11. 11. Histological diagnosis of mucoepidermoid carcinoma is based on the identification of an admixture of epidermoid cells and mucous cells. The most frequent pattern is a multicystic tumour with cystic spaces lined by pale staining, duct-like or epidermoid cells, and mucous cells. In almost all cases more solid areas containing cytologically bland, so- called “intermediate cells” are also seen. Clear cell change may be extensive.
  12. 12. Mucoepidermoid carcinoma of the parotid. (a) Lowgrade lesion Comprising scattered cysts with cellular mural thickenings present only focally (b) Intermediate grade tumour where solid islands predominate over the cystic component
  13. 13. Note that ! Clear cells are frequently seen in mucoepidermoid carcinomas, But careful examination for the presence of: mucous, epidermoid and/or intermediate cells should establish the correct diagnosis.
  14. 14. variants 1-oncocytic variant Polygona / columnar oncocytic cells + scattered mucocytes 2-Sclerosing variant Dense hyalinizing fibrosis 3-Solid MEC Sequamoid and intermediate cells
  15. 15. Brandwein et al.(2001) Low-grade : The cystic pattern is typical of low grade lesions and is seen in over 70% of cases intermediate-grade: show more solid areas and an increased proportion of epidermoid cells. High-grade: cytological atypia, perineural infiltration, necrosis and a more invasive growth pattern. Focal keratinisation and squamous carcinoma-like areas are additional findings in some cases Using this scheme it was shown that all patients with low grade lesions were disease free at 10 years, compared to 70% with intermediate grade and 40% with high grade lesions.
  16. 16. Genetic profile Mucoepidermoid carcinomas do not have a characteristic immunohistochemical profile, but most lesions do show a characteristic (11;19)(q21;p13) translocation and CRTC1-MAML2 (55%-70%) (Gupta, Balasubramanian, & Clark, 2015) gene fusion can be detected by FISH and is a useful marker in difficult cases and in small indeterminate biopsies. Tumours with the translocation were thought to be low to intermediate grade and have a better prognosis in terms of recurrence rates, metastases and tumour-related deaths. (Khurram, Barrett, & Speight, 2017)
  17. 17. Mucoepidermoid carcinoma: FISH analysis using break apart rearrangement probe—Vysis ZytoLight SPEC : MAML2 Dual Colour Break Apart Probe (11q21) • nuclei with one fusion (yellow), • one orange and one green (split) signal pattern indicative of: A rearrangement of one copy of the MAML2 gene region
  18. 18. Most cases of MEC harbour one of two recurrent translocations, either t(11;19)(q21;p13) resulting in a fusion of the genes, CRTC1 to MAML2. or in a small number of mutually exclusive cases t(11;15)(q21;q26) leading to a CRTC3-MAML2 fusion (Simpson, Skálová, Di Palma, & Leivo, 2014)
  19. 19. Tests (Simpson, Skálová, Di Palma, & Leivo, 2014) ; Most cases of MEC can be readily identified on haematoxylin and eosin (H & E), but mucin stains and high molecular weight cytokeratins are useful when respectively mucous or epidermoid cells are few (Hunt, 2011) ; The MECT1-MAML2 translocation can be identified using fluorescent in situ hybridization or with assays based on reverse transcription–polymerase chain reaction (RT-PCR).
  20. 20. differential diagnosis 1-adenosquamous carcinoma of the oral mucosal surface 2-metastatic squamous and primary salivary duct carcinoma 3-Sialometaplasia (Gupta, Balasubramanian, & Clark, 2015); Presence of MAML2 rearrangement may aid in distinction of high-grade mucoepidermoid carcinomas from metastatic squamous cell carcinoma or salivary duct carcinoma.
  21. 21. Prognosis and predictive factors This tumour has a favourable outcome. Most patients present with low-grade tumour and low- stage tumour The median survival of fusion-positive patients appears to be better than those without it ‘low grade better’ Amongst MECs of high histological grade, there is recent evidence that fusion negative tumours behave much more aggressively than fusion-positive ones (Simpson, Skálová, Di Palma, & Leivo, 2014)
  22. 22. Prognosis and predictive factors Low- and intermediate-grade MECs : 1-less aggressive and are generally cured by complete surgical excision. 2-The 10 -year overall survival rates for MECs are approximately Low grade = 90% Intermediate grade = 70% High grade = 25% (Vargas, Cheng, Barrett, Craig, & Speight, 2008)
  23. 23. References: 1. Gupta, R., Balasubramanian, D., & Clark, J. R. (2015). Salivary gland lesions: Recent advances and evolving concepts. Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology, 119(6), 661–674. 2. Hunt, J. L. (2011). An update on molecular diagnostics of squamous and salivary gland tumors of the head and neck. Archives of Pathology & Laboratory Medicine, 135(5), 602–609. 3. Khurram, S. A., Barrett, A. W., & Speight, P. M. (2017). Diagnostic difficulties in lesions of the minor salivary glands. Diagnostic Histopathology, 23(6), 250–259. 4. Simpson, R. H. W., Skálová, A., Di Palma, S., & Leivo, I. (2014). Recent advances in the diagnostic pathology of salivary carcinomas. Virchows Archiv, 465(4), 371–384. 5. Speight, P. M., & Barrett, A. W. (2009). Leading article Prognostic factors in malignant tumours of the salivary glands, 47, 587–593. 6. Vargas, P. A., Cheng, Y., Barrett, A. W., Craig, G. T., & Speight, P. M. (2008). Expression of Mcm-2 , Ki-67 and geminin in benign and malignant salivary gland tumours, 44, 309–318 7. Zhu, S., Schuerch, C., & Hunt, J. (2005). Review and Updates of Immunohistochemistry in Selected Salivary Gland and Head and Neck Tumors. 8. Regezi, J., 2012. Oral Pathology clinical pathological correlation. 6th ed. Missoury: Elsevier, p.204. 9. WHO Classification of Head and Neck Tumours, 4ed, (2017)

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