We present the case of a 65-year-old male with squamous cell carcinoma of the thoracic oesophagus on a background of neurofibromatosis type 1. On computed tomography, he was noted to have a large left-sided superior mediastinal mass. Initially, this mass was thought to be metastatic lymphadenopathy; however, it did not display fluorodeoxyglucose uptake on positron emission tomography. Subsequent biopsy confirmed the mass to be a neurofibroma and the patient commenced definitive chemo-radiation. Positron emission tomography had a major impact on management since the presumed lymph node disease was not included in the radiation field. In addition, positron emission tomography altered prognostic stratification since lymph node involvement is a poor prognostic factor in oesophageal cancer. We could only identify one other case in the English literature in which positron emission tomography was used to distinguish metastatic carcinoma from a neurofibroma, although there are a number of reports that describe the utility of positron emission tomography in differentiating benign neurofibromas from malignant connective tissue tumours.