Treatment and outcome of infantile myofibromatosis

Patients with these tumors usually have an excellent prognosis and the tumors can regress spontaneously. However, about one-third of cases with multicentric involvement will also have visceral involvement, and the prognosis for these patients is poor.[12,13,21]

Treatment options for infantile myofibromatosis include the following:

Ninety-five patients were prospectively enrolled in five Cooperative Weichteilsarkom Studiengruppe (CWS) trials and one registry trial between 1981 and 2016.[22] Localized disease was diagnosed in 71 patients. Forty-two (59%) of these patients were infants younger than 12 months. The mainstay of treatment (applied to 55 children) was watch and wait after initial biopsy or resection. Systemic therapy was only recommended in cases of life-threatening progressive disease or in cases of compression of vital structures or organ dysfunction in the setting of progressive disease. Based on these criteria, chemotherapy was administered to 16 of 71 patients as an individual decision at the treating center: 8 patients received methotrexate/vinblastine, 5 patients received vincristine/dactinomycin/cyclophosphamide (VAC), and 3 patients received other therapies.

The use of combination chemotherapy with vincristine/dactinomycin and vinblastine/methotrexate have proven effective in cases of multicentric disease with visceral involvement and in cases in which the disease has progressed and has threatened the life of the patient (e.g., upper airway obstruction).[12,13,23]

Case reports have described prompt tumor regression in patients with infantile myofibromatosis that have PDGFRB variants when treated with tyrosine kinase inhibitors like imatinib and sunitinib, which inhibit the PDGFRB gain-of-function variant in the tumor.[24-27]