PULMONARY LESION MIMICKING A PRIMARY LUNG TUMOR: METASTATIC LOCALIZATION OF A PRIMARY HEPATIC NEUROENDOCRINE TUMOR - A CASE REPORT

Neuroendocrine tumors (NETs) are rare neoplasms, accounting for approximately 1-2% of gastrointestinal tumors. Primary hepatic neuroendocrine tumors (PHNETs) are extremely uncommon, representing less than 0.3% of all NETs. Pulmonary metastases from PHNETs are exceptionally reported. We report the case of a 79-year-old man presenting with exertional dyspnea and persistent cough.Thoracoabdominal computed tomography revealed a right lower lobe pulmonary mass and multiple hepatic lesions, initially suggesting the presence of two synchronous primary tumors. However, ultrasound-guided liver biopsy demonstrated a well-differentiated grade 3 neuroendocrine tumor, with positive chromogranin A and synaptophysin expression and a Ki-67 proliferation index of 30%. A subsequent transthoracic lung biopsy confirmed metastatic involvement. A comprehensive extension workup revealed no extrahepatic primary tumor or additional metastatic sites. The diagnosis of primary hepatic neuroendocrine tumor with pulmonary metastasis was established. The patient was managed with palliative chemotherapy. This case highlights the diagnostic challenge posed by synchronous pulmonary and hepatic lesions and underscores the crucial role of histopathological and immunohistochemical analysis in distinguishing metastatic disease from multiple primary tumors.