Hepatic Recurrence of Neuroendocrine Tumor Component in Gallbladder Cancer

Area of Science:

• Oncology
• Nuclear Medicine
• Pathology

Background:

• Gallbladder cancer (GBC) diagnosis and staging often rely on imaging.
• Fluorodeoxyglucose (FDG) Positron Emission Tomography (PET) is used to assess metabolic activity in tumors.
• Neuroendocrine tumors (NETs) have distinct metabolic and receptor characteristics.

Purpose of the Study:

• To report a case of gallbladder cancer with unusual metastatic presentation.
• To highlight the diagnostic challenge posed by differing FDG avidity between primary and metastatic lesions.
• To emphasize the importance of integrating various imaging modalities and histopathology for accurate diagnosis.

Main Methods:

• Case presentation of a 60-year-old male patient.
• Review of imaging studies including CT and FDG-PET scans.
• Histopathological analysis of primary tumor and metastatic lesions.
• Somatostatin receptor scintigraphy.

Main Results:

• Primary GBC showed high FDG uptake (SUV max = 6.5).
• Post-surgery hepatic masses exhibited significantly lower FDG uptake (SUV max = 3.7).
• Biopsy confirmed hepatic masses as grade 3 neuroendocrine tumors, with NET components also found in the primary GBC specimen.
• Hepatic masses showed high uptake on somatostatin receptor scintigraphy.

Conclusions:

• Discordant FDG uptake between primary GBC and its metastases (NETs) can complicate diagnosis.
• Somatostatin receptor scintigraphy can be valuable in identifying neuroendocrine metastases.
• Thorough histopathological examination of the primary tumor is essential to identify potential mixed histology.
• This case underscores the need for differential diagnosis when metastatic lesions display different imaging characteristics than the primary tumor.