What genetic abnormalities are seen in mucoepidermoid carcinoma, and what is their prognostic significance?
t(11;19): CRTC1`-MAML2. 40-80% of cases, favorable.
t(11;15): CRTC3-MAML2. 5% of cases, favorable.
CDKN2A deletions are unfavorable even when concurrent with above.
What genetic abnormalities are seen in adenoid cystic carcinoma? What is their significance?
t(6;9): MYB-NFIB. Seen in 30-85% of cases*, not prognostic.
1p36.33-p35.3 losses: Unclear significance.
*Almost all ACCs have overexpression of MYB mRNA/protein, including transfusion-negative cases. Some have t(8;9).
What genetic abnormalities are seen in salivary duct carcinoma, and what is their significance?
amp(17q21.1): ERBB2 amplification. 40% of cases, can be targeted for anti-Her2 therapy.
3q26.32: PIK3CA mutations. 20% of cases, unclear significance.
TP53, PTEN, H-RAS mutations. May decrease efficacy of HER2 blockade.
What genetic abnormality is seen in mammary analog secretory carcinoma?
What other lesion is it most analogous to?
Shares morphologic and molecular features of secretory carcinoma of breast.
What lesion is salivary duct carcinoma most similar to, both morphologically and molecularly?
Breast carcinoma with luminal AR-positive, apocrine phenotype.
What genetic abnormality is seen in polymorphous low-grade adenocarcinoma?
In cribriform adenocarcinoma of minor salivary glands?
PRKD-1 gene mutations
Chromosomal rearrangements of PRKD genes (-1, -2, -3)
What genetic abnormalities are seen in pleomorphic adenoma and carcinoma ex pleomorphic adenoma?
8q12 rearrangements: PLAG1. 25-30% of cases.
12q13-15 rearrangements: HMGA2. 10-15% of cases.
Carcinoma ex pleomorphic adenoma can have both of above, plus additional alterations (MDM2, MYC, HER2)
What genetic abnormality is seen in hyalinizing clear cell carcinoma?
What lesion is it most analogous to?
t(12;22): EWSR1-ATF. Almost all cases! But be careful with nonspecific EWSR rearrangements.
Clear cell odontogenic carcinoma
What genetic abnormality is seen in basal cell adenoma and adenocarcinoma?
With what other lesion is it morphologically and molecularly similar?
LOH at 16q12-13: CYLD.
(less significant: CTTNB1, LEF-1)
Dermal eccrine cylindromas
What genetic abnormalities are seen in epithelial-myoepithelial carcinoma?
In myoepithelial carcinoma?
HRAS codon 61 mutations