Isolated Splenic Myofibroma in a Child on 18 F-FDG PET/CT.

We present a rare case of an isolated splenic myofibroma in a child evaluated with 18 F-FDG PET/CT. An 8-year-old boy underwent PET/CT for a left cervical mass, which incidentally revealed a splenic nodule (1.3×1.0 cm) with markedly increased 18 F-FDG uptake (SUV max =8.1). MRI showed an enhancing, low T2-weighted signal nodule without diffusion restriction. Histopathology after splenectomy confirmed myofibroma. Isolated myofibromas are rare benign spindle cell tumors in children and can demonstrate intense 18 F-FDG uptake, mimicking malignancy. Awareness of this potential false-positive pitfall is essential in pediatric PET interpretation.