Abundant dendritic cells express HLA-DR in pleomorphic adenomas

The prognostic impact of human leukocyte antigen (HLA) class I antigen abnormalities in salivary gland cancer. A clinicopathological study of 288 cases

AIMS

To study abnormalities of proteins of the major histocompatibility complex class I in a series of 288 salivary gland carcinomas, and to correlate findings with patients' overall survival (OS).

METHODS AND RESULTS

Protein expression of human leukocyte antigen (HLA)-A, heavy chain (HC)-10, β2 -microglobulin, low molecular weight polypeptides (LMP) 2 and 7, transporters associated with antigen processing (TAP) 1 and 2, calnexin, calreticulin, endoplasmic reticulum (ER) p57 and tapasin was evaluated by immunohistochemistry and semiquantitatively analyzed. As compared with normal salivary gland tissue, HLA-A, LMP7, TAP2 and HLA class I were significantly down-regulated in salivary gland carcinomas, whereas β2 -microglobulin, calnexin, LMP2, and TAP1 were upregulated. Expression of calreticulin, ERp57 and tapasin was unaltered. In univariate Kaplan-Meier analyses, low expression of LMP7 (P = 0.005) and high expression of β2 -microglobulin (P = 0.028), HLA-A (P < 0.001), TAP1 (P = 0.01), and tapasin (P < 0.001) were significantly associated with shorter OS. In multivariate analysis incorporating tumour stage, nodal/distant metastasis, and grade, HLA-A (P = 0.014), LMP7 (P = 0.033), and tapasin (P = 0.024), as well as distant metastasis (P = 0.012) and high tumour grade (P < 0.001), remained statistically significant.

CONCLUSION

The prognostic influence of up-regulated HLA-A and tapasin and down-regulated LMP7 may provide a rationale for targeting these specific components of the antigen processing and presentation pathway in salivary gland carcinomas.

Immunoprofile of a carcinosarcoma of the submandibular gland

Carcinosarcomas are a very rare group of true malignant tumors of the salivary gland. As the name indicates, the tumor is composed of an epithelial and a mesenchymal component, both malignant. We report a case of carcinosarcoma of the submandibular gland in an 86-year-old woman. The epithelial component showed a squamous carcinoma phenotype, whereas the mesenchymal component was morphologically similar to a fibrosarcoma. The epithelial component was strongly positive for CK13, CK14, and AE1/AE, and groups of positive cells were seen for CK19 and vimentin. The whole mesenchymal component was positive for vimentin, negative for cytokeratins, and focal cells were positive for smooth- muscle actin. Both components were strongly positive for P53 and Cyclin D1, and focally positive for MDM2. Rare multinucleated giant cells showed expression of CD68, and focal dendritical cells on carcinomatous nests were positive for S-100. The CK7, CK8, Factor XIIIa, c-erbB-2, P16, CDK-4, Rb1, and E2F-1 were not detected in these 2 groups of malignant cell populations.

Two-colour immunofluorescence marker study of pleomorphic adenomas

Extensive use of two-colour immunofluorescence staining for various cell markers in pleomorphic adenoma, revealed three consistent phenotypic features: (1) keratin polypeptide No. 14, which was virtually restricted to myoepithelial cells (MEC) in normal salivary glands, appeared in a large fraction of the tumour cells, suggesting that the principal neoplastic element is derived from MEC or their immediate precursors; (2) a complex co-expression pattern of various cell markers was found, with extensive concurrence of keratin and vimentin in strands of MEC-like and myxoid tumour cells, probably reflecting different degrees of tumour cell differentiation; and (3) two phenotypically distinctive dendritic cell populations were identified, one consisting of keratin positive tumour cells and the other of HLA-DR positive but keratin negative stromal cells. The significance of these findings with regard to the histogenesis and complex morphology of pleomorphic adenoma is discussed.