The 'Starburst' Sign: A Novel Description of PET Images in Carcinoma of Unknown Primary.

BACKGROUND/AIM: Carcinoma of unknown primary (CUP) poses a formidable diagnostic challenge, characterised by high mortality rates and an elusive primary tumour site. While Positron emission tomography (PET) scans are routinely employed in the initial evaluation of CUP patients, identifying the primary tumour remains an ongoing struggle. In light of this, the aim of this case report is to introduce a novel radiological description, termed the 'Starburst' sign, derived from distinctive PET scan appearances associated with CUP. CASE REPORT: In this report, we present the case of a 47-year-old female patient who presented with abdominal symptoms. Upon investigation, extensive peritoneal disease was observed, yet the primary tumour source remained unidentified. Despite further diagnostic efforts, including a normal gastroscopy, a PET scan was able to confirm the presence of high-volume metastatic disease, without an identifiable primary tumour. Palliative treatment was initiated, but unfortunately, the patient's condition deteriorated rapidly, leading to her demise. CONCLUSION: The 'Starburst' sign, a unique radiological description of CUP in PET scans, has significant potential in advancing our understanding of the disease. It provides a visual analogy to a dying star, aiding comprehension of complex pathophysiology and implications of metastatic lesions. The introduction of the 'Starburst' sign benefits patients and healthcare professionals, enhancing education, assessment, and treatment of CUP. This novel description contributes to knowledge in the field and can impact clinical management.