J Pathol Transl Med.  2018 Nov;52(6):411-415. 10.4132/jptm.2018.07.15.

Squamous Metaplasia in Pleomorphic Adenoma: A Diagnostic and Prognostic Enigma

Affiliations
  • 1Department of Oral and Maxillofacial Pathology and Microbiology, I.T.S. Dental College, Hospital and Research Centre, Greater Noida, India. sharmaswatisharma86@gmail.com
  • 2Department of Oral Medicine and Radiology, I.T.S. Dental College, Hospital and Research Centre, Greater Noida, India.

Abstract

Pleomorphic adenoma (PA) is the most common benign salivary gland tumor. Histologically, squamous metaplasia has been reported in PA, but has rarely been documented as being extensive enough to cause significant misdiagnosis. Here, we present an unusual case of PA in a 50-year-old female patient presenting with swelling on the postero-lateral aspect of the palate for a week. Histopathologically, the tumor exhibited the features of conventional PA with extensive squamous metaplasia and giant keratotic lamellae in cyst-like areas. Such exuberant squamous metaplasia and keratin can be a diagnostic and prognostic pitfall and lead to overtreatment of the patient.

Keyword

Squamous metaplasia; Pleomorphic adenoma; Pathology

MeSH Terms

Adenoma, Pleomorphic*
Diagnostic Errors
Female
Humans
Medical Overuse
Metaplasia*
Middle Aged
Palate
Pathology
Salivary Glands

Figure

  • Fig. 1. (A) Swelling associated with central ulceration covered by a fibrino-purulent membrane and surrounded by palatal erythema can be seen on the right distal side of the hard palate, laterally. (B) A well-encapsulated tumor removed in toto from the palate.

  • Fig. 2. (A) Reconstructed panoramic image shows the polyp at the level of the mid right maxillary sinus. (B) Axial section shows inflamed sinus lining involving the right maxillary sinus. (C) Cone beam computed tomography (CBCT) mid-coronal section of the right maxillary third molar (18) showing the soft tissue shadow palatally. (D) Two-three dimensional CBCT image showing the antero-posterior extent of the swelling.

  • Fig. 3. (A) The periphery of the tumor with classical features of pleomorphic adenoma having abundant ducts dispersed in a myxoid and hyalinized background with multiple keratin-filled cystic areas. (B) Multitude of features, including variably shaped epithelial cells, ducts, and squames. Keratin-filled cysts dispersed in the myxoid stroma. (C) Abundant myoepithelial cells around the ducts giving the appearance of a swarm of bees. (D) Massive epithelial lined cysts with keratotic lamellae and the lining budding into the stroma.


Reference

1. Neville B, Damm DD, Allen C, Bouquot J. Oral and maxillofacial pathology. 3rd ed. St. Louis: Elsevier;2009. p. 473–506.
2. Rajendran R, Sivapathasundharam B. Shafer’s text book of oral pathology. 7th ed. Noida: Elsevier;2012. p. 223–57.
3. Kaveri H, Gopalkrishnana K, Venkatesh A. Cystic and florid squamous metaplasia in pleomorphic adenoma of palate: a diagnostic dilemma. Asian J Med Sci. 2014; 5:108–10.
4. Dardick I, Jeans MT, Sinnott NM, Wittkuhn JF, Kahn HJ, Baumal R. Salivary gland components involved in the formation of squamous metaplasia. Am J Pathol. 1985; 119:33–43.
5. Jaishankar HP, Hegde U, Nagpal B. Florid squamous metaplasia and keratin cyst formation in palatal minor salivary gland tumor: a diagnostic challenge. Int J Health Sci Res. 2016; 6:516–20.
6. Compagno J, Wong RT. Intranasal mixed tumors (pleomorphic adenomas): a clinicopathologic study of 40 cases. Am J Clin Pathol. 1977; 68:213–8.
Article
7. Takegawa K, Mitsumori K, Onodera H, et al. Induction of squamous cell carcinomas in the salivary glands of rats by potassium iodide. Jpn J Cancer Res. 1998; 89:105–9.
Article
8. Lam KY, Ng IO, Chan GS. Palatal pleomorphic adenoma with florid squamous metaplasia: a potential diagnostic pitfall. J Oral Pathol Med. 1998; 27:407–10.
Article
9. Lim S, Cho I, Park JH, Lim SC. Pleomorphic adenoma with exuberant squamous metaplasia and keratin cysts mimicking squamous cell carcinoma in minor salivary gland. Open J Pathol. 2013; 3:113–6.
Article
10. Goulart MC, Freitas-Faria P, Goulart GR, et al. Pleomorphic adenoma with extensive squamous metaplasia and keratin cyst formations in minor salivary gland: a case report. J Appl Oral Sci. 2011; 19:182–8.
Article
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