MDB-02. RECURRNET SPINAL DESMOID FIBROMATOSIS IN A CHILD WITH APC GERMLINE MUTATION-RELATED MEDULLOBLASTOMA

Abstract

Abstract BACKGROUND Familial adenomatous polyposis (FAP) is an autosomal-dominant dominant Familial Cancer Syndrome FCs Caused by Germline inactivation of adenomatous polyposis coli (APC) tumor suppressor gene, results in up-regulation of the WNT signaling pathway which increases the risk of colorectal cancer CRC, colon polyposis and extracolonic tumors like gastric and duodenal carcinomas WNT-activated Medulloblastoma MBL and Desmoid fibromatosis (DF) DF are locally aggressive soft tissue tumors with high local recurrence rates after Surgical excision role of adjuvant chemotherapy or Radiotherapy is still unclear. METHODS A 6-year-old boy product of non-consanguineous marriage with positive family HX brain tumor Diagnosed with Non-Metastatic Average Risk MBL WHO grade IV classic histology, he had craniotomy and Gross tumor resection followed by craniospinal irradiation at 23.4 Gy, plus a boost to posterior fossa/tumor bed up to 54 Gy, followed by 8 maintenance chemotherapy cycles as HIT-MED protocol Cisplatin/VCR/CCNU total. 3 years post end of therapy the pateint was in complete remission from MBL when routing MRI surveillance showed a new left paravertebral muscle lesion within the irradiation field from T1 to T4 levels which progressed gradually over a short follow-up time he had surgical resection of the tumor with Pathological diagnosis of Desmoid fibromatosis. after six months he had a second recurrence of the spinal tumor that needed a second surgical resection. Result: positive Genetic testing for Germline pathogenic mutation of APC gene exons 7 to 16 confirmed the diagnosis of autosomal familial adenomatous polyposis type 1(FAP1). Up to date, he is stable on endoscopic and MRI surveillance with radiological evidence of slow progression of the paraspinal tumor CONCLUSION Medulloblastomas associated with APC germline mutation have favorable outcomes that may need de-escalating therapeutic protocol with reduced intensity craniospinal irradiation aiming to reduce the incidence of secondary tumors after adjuvant treatment for MBL