Carcinoma ex pleomorphic adenoma of salivary gland, CXPA

This is a malignant epithelial tumour arising within a pleomorphic adenoma (mixed salivary gland tumour) and accounts for between 5% and 15% of all salivary gland malignancies.

Histopathology

Distribution of carcinoma subtypes in 70 patients with carcinoma ex pleomorphic adenoma¹:

Adenocarcinoma NOS	31
Salivary duct carcinoma	24
Adenosquamous carcinoma	5
Undifferentiated carcinoma	3
Adenoid cystic carcinoma	3
Myoepithelial carcinoma	2
Epithelial-myoepithelial carcinoma	1
Sarcomatoid carcinoma	1

Immunohistochemistry

AE1/AE3	67/691
CK7	65/691
CK20	9/691
EMA	59/691
CEA	52/691
Vimentin	36/691
S-100	20/691
Actin	5/691
GFAP	2/691
p53	28/691
c-erbB-2	21/691

Prognosis

Prognostic factors include the extent of invasion beyond the capsule, with 5 to 8 mm being the critical extent. Intracapsular and minimally invasive CXPA have almost no malignant potential².

References

¹Lewis, J. E., Olsen, K. D., Sebo, T. J. Carcinoma ex pleomorphic adenoma: pathologic analysis of 73 cases. Human Pathol 2001;32:596-604.

²Perez-Ordonez B. Selected topics in salivary gland tumour pathology. Current Diagnostic Pathology2003;9:355-365.