Schwannoma as a source of false positive in PET/CT: diagnostic and therapeutic implications in a clinical case

A 48-year-old male presented to his Primary Care Physician after experiencing discomfort and pruritus in the left shoulder for one and a half years, followed by the onset of pain in the left axilla and the palpation of a nodule. An ultrasound was performed, revealing a well-defined, avascular, hypoechoic nodule located in the deep tissue planes. Subsequently, a contrast-enhanced CT scan was carried out, which identified a nonspecific focal lesion in the left axilla. Both imaging reports recommended a biopsy of the lesion due to its size and location. One month later, an ultrasound-guided core needle biopsy was performed. While awaiting histopathological analysis results, a PET/CT scan was conducted to rule out malignancy. The lesion demonstrated moderate FDG uptake, slightly higher than that of the reference liver parenchyma, suggesting a benign etiology. Ultimately, the histopathological examination confirmed the diagnosis of a benign schwannoma.