Primary neuroendocrine tumor of the superior pubic ramus presenting as inguinal swelling: A rare case with radio-pathological correlation

Primary neuroendocrine tumors (NETs) of bone are exceedingly rare, and most osseous NETs represent metastases from an occult primary site. We report a rare case of primary NET arising from the left superior pubic ramus, presenting as progressive left inguinal swelling. An 83-year-old male presented with groin swelling, pain, and limping for 3 months. Radiographs and contrast-enhanced computed tomography demonstrated an osteolytic lesion in the left superior pubic ramus with an associated soft-tissue mass. Magnetic resonance imaging showed an aggressive marrow-replacing lesion with central necrosis, cortical destruction, soft-tissue extension, and regional lymphadenopathy, initially suggesting metastatic disease or primary bone sarcoma. Comprehensive systemic evaluation excluded an extra-osseous primary tumor. Biopsy with immunohistochemistry confirmed neuroendocrine differentiation, with a Ki–67 index consistent with World Health Organization (Grade 2). A diagnosis of primary osseous NET was established. Despite chemotherapy and radiotherapy, rapid disease progression occurred, and the patient expired, emphasizing diagnostic challenges and the importance of radiologic–pathologic correlation.