Medulloblastoma in a Child with Gorlin Syndrome: Calcifications or Metastasis

Abstract

Introduction. Gorlin syndrome is a hereditary cancer predisposition disorder caused by ger- mline mutations in the Sonic hedgehog (SHH) pathway, most commonly involving SUFU and PTCH1. SUFU mutations confer high risk of early-onset SHH-activated medulloblastoma. Ra- diotherapy is often avoided due to secondary malignancy risk, and characteristic intracranial calcifications may complicate imaging and mimic metastases or relapse. Methods. We report a pediatric case of classic SHH-activated medulloblastoma associated with a germline SUFU mutation. Results. A 16-month-old boy presented with vomiting, ataxia and abducens nerve palsy. Brain MRI revealed a fourth-ventricle tumor causing obstructive hydrocephalus with cerebellar lep- tomeningeal dissemination and bilateral calcifications, some demonstrating contrast enhance- ment; no spinal dissemination was detected. Near-total resection was performed. Histopathology confirmed classic medulloblastoma, SHH-activated, TP53 wildtype. Genetic testing identified a SUFU mutation. The patient received three induction and two maintenance chemotherapy courses. Treatment was complicated by myelosuppression and febrile neutropenia requiring an- timicrobial therapy and transfusions. Subsequently, focal seizures and unilateral weakness de- veloped. MRI showed progressive white matter changes consistent with posterior reversible en- cephalopathy syndrome (PRES) and calcified lesions. EEG was normal, carbamazepine was initi- ated. Given lesion distribution, temporal evolution, and the underlying SUFU mutation, imaging findings were interpreted as mutation-associated and treatment-related rather than relapse. The patient remains under surveillance without recurrence; his condition has improved. Conclusions. In SUFU-associated Gorlin syndrome, intracranial calcifications and PRES may mimic medulloblastoma relapse. Accurate interpretation requires integration of genetic back- ground, clinical course, and multidisciplinary imaging review to avoid overtreatment.