cellular pleomorphic adenoma

Definition: Pleomorphic adenoma is the most common salivary gland neoplasm and infrequently undergoes malignant transformation.

Cellular pleomorphic adenomas show increased cellularity, bizarre cells with hyperchromatic nuclei (often limited to focal areas), and focally increased mitotic activity. These changes are not advanced enough to qualify them as malignant.

Cellular pleomorphic adenoma can have a predominantly solid growth of the epithelial cells and a few acinar structures.

The epithelial cells can also be arranged in acinar and trabecular patterns with mild cytologic atypia. The atypia is not enough to classify them under malignant category.

Atypical pleomorphic adenomas can show features such as anaplasia, atypical mitosis, coagulative tumor necrosis and zones of acellular hyalinization. These features might portend malignant transformation.

Pleomorphic adenomas with atypical features should be sampled extensively to rule out the possibility of malignancy.

Differential diagnosis

 carcinoma ex-pleomorphic adenoma

• CEPA is typically an infiltrative neoplasm with features as cellular pleomorphism, high mitotic activity, peri-neural and vascular invasion.

Open references

 Polymorphous low grade adenocarcinoma has a consistent p63+/p40- immunophenotype that helps distinguish it from adenoid cystic carcinoma and cellular pleomorphic adenoma. Rooper L, Sharma R, Bishop JA. Head Neck Pathol. 2015 Mar;9(1):79-84. doi : 10.1007/s12105-014-0554-4 PMID: 24969705

 Juvenile cellular pleomorphic adenoma. Ananthaneni A, Undavalli SB. BMJ Case Rep. 2013 May 24;2013. pii: bcr2012007641. doi : 10.1136/bcr-2012-007641 PMID: 23709529

 2009. https://www.jstage.jst.go.jp/article/sujms/21/4/21_4_269/_pdf

Paywall references

 Atypical features in pleomorphic adenoma—a clinicopathologic study and implications for management. Ethunandan M, Witton R, Hoffman G, Spedding A, Brennan PA. Int J Oral Maxillofac Surg. 2006 Jul;35(7):608-12.
PMID: 16540285

 Fine needle aspiration cytology of cellular pleomorphic adenoma. Elsheikh TM, Bernacki EG. Acta Cytol. 1996 Nov-Dec;40(6):1165-75. PMID: 8960024