Adenoid cystic carcinoma of salivary gland

Histopathology

There are three characteristic patterns: cribriform, tubular and solid, most tumours being composed of a mix of these³. Tumour nuclei are typically small angulated and hyperchromatic; there is scanty cytoplasm.

Adenoid cystic carcinoma may undergo dedifferentiation to a high grade tumour with necrosis, a high mitotic rate and loss of the distinction between ductal and myoepithelial cells.

Immunohistochemistry

	ductal epithelial cells	basaloid cells (myoepithelial differentiation)
cytokeratins	strong⁰	weak⁰
AE1/AE3	22/22⁶
cytokeratin 7	20/20², 22/22⁶
cytokeratin 8/18	53/53²
cytokeratin 13	0/20²
cytokeratin 14	33/33²
cytokeratin 17	5/5²
cytokeratin 19	28/28²
cytokeratin 20	0/22⁶
CEA	positive⁰	negative⁰
EMA	positive⁰	negative⁰
vimentin	negative⁰	positive⁰
S-100	negative⁰	positive⁰
actin	negative⁰	variable⁰
Calponin	negative⁰	positive⁰
CD43		positive, membranous⁴
CD117	positive¹

Dedifferentiated adenoid cystic carcinoma:

	differentiated ACC		dedifferentiated ACC
	epithelium	myoepithelium	dedifferentiated ACC
Pankeratin	4/4⁷	4/4, focal⁷	4/4⁷
AE1/AE3	2/2⁷	2/2, focal⁷	2/2⁷
Cam5.2	4/4⁷	4/4, focal⁷	4/4⁷
p63		7/8⁷	1/8, focally in squamoid component⁷
Calponin		1/1⁷
SMA		4/4⁷
S100	6/7, focal⁷	1/7⁷	6/7⁷
CD117	6/6⁷		6/6⁷
Androgen receptor			0/6⁷
Her-2			0/6⁷

Cytogenetics

Loss of heterozygocity at 6q23-25 is common⁵.

Molecular genetics

There is overexpression of genes encoding basement membrane and extracellular matrix proteins⁵.

Differential diagnosis

Positivity for CD43 favours adenoid cystic carcinoma.

Prognosis

Adenoid cystic carcinomas are slowly progressive with local recurrences and late metastases. Tumours with more than 30% solid pattern may have a worse prognosis³.

Management

Although adenoid cystic carcinomas are positive for CD117, tyrosine kinase receptor inhibitor has not been found to be beneficial⁴.

References

⁰Diagnostic histopathology of tumors. Edited by CDM Fletcher. 2nd edition. Churchill Livingstone. Page 269.

¹ Berman, J., O'Leary, T. J. Gastrointestinal stromal tumor workshop Human Pathol 2001; 32:578-582.

² Chu, P. G. and L. M. Weiss (2002). "Keratin expression in human tissues and neoplasms." Histopathology 40(5): 403-39. (Summary data from multiple papers)

³ Perez-Ordonez B. Selected topics in salivary gland tumour pathology. Current Diagnostic Pathology2003;9:355-365.

⁴ Hotte SJ, Winquist EW, Lamont E, et al. Imatinib mesylate in patients with adenoid cystic cancers of the salivary glands expressing c-kit: a Princess Margaret Hospital phase II consortium study. J Clin Oncol 2005; 23:585-90

⁵ Cheuk W,Chan JK. Advances in salivary gland pathology. Histopathology 2007; 51:1-20

⁶ Meer S,Altini M. CK7+/CK20- immunoexpression profile is typical of salivary gland neoplasia. Histopathology 2007; 51:26-32

⁷ Seethala RR, Hunt JL, Baloch ZW, et al. Adenoid cystic carcinoma with high-grade transformation: a report of 11 cases and a review of the literature. Am J Surg Pathol 2007; 31:1683-94

This page last revised 30.12.2007.