IMG-103. Molecular Characterization of Meningiomas with Low SSTR-PET/CT Uptake: Insights from a Case Series

Meningiomas are generally characterized by high expression of somatostatin receptors (SSTRs), which makes them suitable candidates for PET imaging with SSTR-directed tracers such as 68Ga-DOTATATE. However, certain meningiomas demonstrate low radiotracer uptake, which can pose diagnostic challenges. This case series aims to examine the molecular and histopathological profiles of meningiomas with low SSTR-PET uptake, exploring potential genetic mutations and their implications for clinical management. Patients with SSTR PET/CT of a histologically confirmed meningioma between 2000 and 2024 and visually low uptake intensity on SSTR PET were included in this retrospective analysis. Histopathological assessment and methylome analysis were performed. A 50-year-old male patient underwent surgical resection for a spinal WHO grade I meningioma. 16 years after the initial diagnosis, the patient experienced tumor recurrence. SSTR-PET/CT imaging revealed low radiotracer uptake. Interestingly, 18F FDG PET/CT showed high Uptake (SUVmax: 5,7) in this area. Histopathological analysis confirmed an anaplastic meningioma, which was found to harbor a homozygous deletion of CDKN2A/B and a loss of chromosome 1p. A 49-year-old male patient underwent radiosurgical treatment for a suspected temporal meningioma in 2017. The patient experienced tumor recurrence both infratentorially and supratentorially and underwent surgical resection of the temporal tumor component. Postoperative SSTR-PET/CTdemonstrated residual SSTR uptake in the temporal region and low SSTR uptake in the infratentorial region. Methylation analysis of the resected tissue revealed no evidence of CDKN2A/B deletion but 1p loss. In the following months, a biopsy of the infratentorial tumor exhibiting low uptake was performed. Histopathological evaluation confirmed a diagnosis of anaplastic meningioma, and homozygous loss of CDKN2A/B. A 56-year-old male patient with a history of surgically treated atypical meningioma (WHO grade II) underwent SSTR-PET/CT. The imaging demonstrated low uptake of the SSTR-targeted radioligand. Histopathological analysis revealed a homozygous loss of CDKN2A/B. Meningioma with low tracer uptake on SSTR PET may be associated with aggressive features such as homozygous deletion of CDKN2A/B and has implications on theranostics.