Fibroblastic reticular cell tumour of the internal iliac lymph node presenting as a hypervascular lesion and mimicking a pseudoaneurysm: an extremely rare diagnosis.

A woman in her 50s presented with a rounded and hypervascular lesion in the right internal iliac lymph node chain, contacting with small branches of the anterior division of the internal iliac artery. Since the lesion matched the blood arterial pool in CT and the patient exhibited multiple vascular abnormalities that suggested segmental arterial mediolysis, a pseudoaneurysm hypothesis was initially made. Arteriography was realised due to the intention for embolisation of the pseudoaneurysm, but the dynamic behaviour during the exam suggested a hypervascular tumour more. An MRI was conducted, bringing new evidence, favouring the possibility of a neoplasm. The lesion excision was performed and sent to pathology. Morphological and immunohistochemical findings suggested a rare case of a fibroblastic reticular cell tumour of the internal iliac lymph node.