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PDGFRB gain-of-function mutations most prominent in pediatric myofibroma

In myofibroma and myofibromatosis, researchers found that gain-of-function mutations of PDGFRB only affect children, according to a retrospective study in JAMA Dermatology.

Researchers evaluated the significance of PDGFRB mutations as a diagnostic biomarker and therapeutic target in a group of 102 patients.

The archived samples from patients diagnosed with sporadic myofibroma, myopericytoma or myofibromatosis according to WHO classification were analyzed from clinical centers in Belgium, France, the U.S. and the Netherlands.

Tumor samples were analyzed by targeted deep sequencing of PDGFRB.

In 69 patients with tumor samples, 60 were children (mean age, 7.8 years) and 29 were girls. Of the nine adult patients, four were women.

None of the patients had a family history of myofibroma or myofibromatosis, according to researchers.

Researchers identified PDGFRB mutations in 25 patients including infants and children but no adults.

Additionally, PDGFRB mutations were more frequent in infantile myofibromatosis compared with solitary tumors (68% vs. 24%; P = .002).

Researchers found visceral involvement in three patients carrying PDGFRB mutations, including one patient with multicentric myopericytoma.

From the 25 patients with PDGFRB variants, 11 patients (44%) carried multiple mutations.

“Of the 11 patients, seven patients (64%) had multicentric disease, with no significant association between multiple-hit status of PDGFRB and clinical phenotype,” Guillaume Dachy, MD, of the Experimental Medicine Unit, de Duve Institute, Catholic University of Louvain, Brussels, and colleagues wrote. “We found a broad catalog of 18 different PDGFRB mutations in myofibroma lesions, 12 of which were novel.”

The findings highlight the molecular basis of the pericytic tumors and the significance of PDGFRB sequencing for diagnosis, prognosis and therapy of soft tissue neoplasms in children, researchers concluded. – by Abigail Sutton

Disclosures: Dachy reports receiving grants and being a recipient of Aspirant fellowship from Fonds de la Recherche Scientifique during the study. Please see the study for the other authors’ relevant financial disclosures.