Novel fusion gene leads to diagnosis of adenoid cystic carcinoma microbiologystudy

A paper published by researchers at Fox Chase Cancer Center highlights the case of a patient who was diagnosed with adenoid cystic carcinoma (ACC) after a molecular panel identified the presence of an atypical fusion gene.

The paper, “NFIB::PHACTR2, a Novel Atypical Fusion Gene Identified in Adenoid Cystic Carcinoma of the Palate,” is published in the journal Virchows Archiv.

The case underscores the importance of molecular testing in correctly diagnosing certain cancers, said first author Shuanzeng “Sam” Wei, MD, Ph.D., an Associate Professor in the Department of Pathology and Medical Director of the Clinical Genomics Laboratory at Fox Chase.

He said the team published their case study to raise awareness that the absence of the typical MYB/MYBL1 fusion genes does not rule out ACC and that the novel NFIB fusion gene can also be diagnostic.

“It’s a simple case report, but it’s important information for practicing pathologists to be aware of this potential pitfall,” Wei said.

ACC is one of the most common malignancies of the salivary glands and has a poor long-term prognosis. It can usually be diagnosed correctly through biopsy; however, diagnosis can be more difficult when the tumor is found in an unusual form or location, which is what occurred in this case.

The 1.7-centimeter palate tumor was initially diagnosed as a salivary gland neoplasm. Molecular testing was negative for two fusion genes commonly used to identify ACC, MYB::NFIB or MYBL1::NFIB. However, the panel did find a different fusion gene, NFIB::PHACTR2.

Wei said it was significant that all three fusion genes share a common partner in NFIB.

“If you have an NFIB fusion gene in a salivary gland tumor, it is most likely an adenoid cystic carcinoma,” he said.

Knowing the correct diagnosis is essential, because ACC is more aggressive and can grow along the nerve, requiring a different treatment approach from other tumors. That might include removing the nerve or taking out more tissue during surgery to get clear margins.

“It’s personalized medicine,” Wei said. “That’s why we need to do molecular testing before surgery. If we have the accurate diagnosis, we can give the patient better management and treatment.”

He noted that molecular testing is not yet widely available and may not be offered at many smaller community hospitals. Cases should be referred to specialized cancer centers to confirm diagnosis, he said.