(P 264) RARE CASE OF INFLAMMATORY MYOFIBROBLASTIC TUMOR (IMT) IN NEWBORN

Author(s)

Lisa Hall, DO (she/her/hers)

Pediatric Hematology/Oncology Fellow
Nationwide Children's Hospital; Center for Childhood Cancer Research, The Abigail Wexner Research Institute, Nationwide Children’s Hospital
Columbus, Ohio, United States

Co-Author(s)

Kathleen Schieffer, PhD

Clinical Assistant Professor of Pathology and Pediatrics
Steve and Cindy Rasmussen Institute for Genomic Medicine, The Abigail Wexner Research Institute, Nationwide Children’s Hospital
Columbus, Ohio, United States
KT

Karen Tsuchiya, MD

Steve and Cindy Rasmussen Institute for Genomic Medicine, The Abigail Wexner Research Institute, Nationwide Children’s Hospital
Columbus, Ohio, United States
MC

Miriam Conces, MD

Department of Pathology and Laboratory Medicine, Nationwide Children’s Hospital; Department of Pathology, The Ohio State University College of Medicine
Columbus, Ohio, United States
Meredith Lind, MD

Professor/ Pediatric Otolaryngologist
Department of Otolaryngology, Nationwide Children's Hospital; Department of Otolaryngology, The Ohio State University College of Medicine
Columbus, Ohio, United States
BS

Bhuvana Setty, MD

Professor of Pediatrics
Nationwide Children's Hospital
Columbus, Ohio, United States
NY

Nicholas Yeager, MD

Department of Hematology/Oncology, Nationwide Children's Hospital
Columbus, Ohio, United States
NA

Nicholas Armando

Nationwide Children’s Hospital
Columbus, Ohio, United States

Objective: IMT is a rare mesenchymal tumor. Approximately half of cases harbor a fusion involving the anaplastic lymphoma kinase (ALK) gene. ALK is a transmembrane tyrosine kinase receptor vital for neuronal cell growth, division, and maturation. Activation of the ALK protein kinase domain results in overexpression, uncontrolled cell growth, constitutive dimerization, and tumorigenesis. Standard treatment for IMT is surgical resection with chemotherapy or targeted therapy for unresectable disease. We present a case of a newborn with IMT who demonstrated a marked clinical response to ALK inhibitor therapy highlighting personalized oncologic treatment in very young pediatric patients to achieve favorable outcomes with minimal adverse effects.

Methods: Right neck mass was diagnosed prenatally in a 36-week female infant. Imaging studies (CT neck, MR head/neck) showed a 7.1 x 6.5 x 5.8cm mass of the right neck with erosion/remodeling of adjacent bony structures. Biopsy demonstrated proliferation of spindle to stellate cells with mixed inflammatory infiltrate. Immunohistochemistry showed positivity for SMA, patchy positivity for ALK1, CAM5.2 and desmin, and was negative for myogenin, myoD1, S100, pancytokeratin, CD34, and MUC4. Metastatic work up was negative. Somatic disease germline comparator (SDGC) exome sequencing, RNA-sequencing, and RT-PCR demonstrated a LRRFIP1::ALK fusion.

Results: Given the inability to surgically resect the mass without substantial comorbidities, treatment was started with vinblastine/methotrexate. Lorlatinib was added after identification of the ALK fusion. Chemotherapy was discontinued after a total of six weeks and lorlatinib monotherapy continued for seven months. No major side effects were noted. Substantial reduction in tumor size allowing surgical removal. Resected tissue showed treatment-related changes with no residual proliferative changes or ALK expression.

Conclusion: We present the case of an infant with a prenatally diagnosed, unresectable neck mass, confirmed IMT with LRRFIP1::ALK fusion. Only a limited number of IMT cases diagnosed in the prenatal period have been described in the literature. This case is further characterized by the infant’s complete response to treatment, highlighting the feasibility and effectiveness of personalized, targeted therapy in very young patients.