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

Abstract

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.

Keywords: Oncology; Pathology; Radiology.

Figure 1

Arterial phase CT scan revealing a hypervascular lesion in the axial (A), coronal (B) and three-dimensional reformation (C). The lesion enhancement follows that of vessels like the aorta and the iliac arteries (blood pool) and contact to small-sided branches of the right internal iliac artery is seen, resembling a vascular origin—like an aneurysm or pseudoaneurysm.

Figure 2

Dynamic images of the arteriography. (A) Early phase shows the normal opacification of the internal iliac artery. (B) Mid-phase shows an initial opacification of the tumour, but with different density from the vascular structures around. (C) The lesion is fully filled by the contrast agent while the internal iliac artery and its branches are washed out.

Figure 3

Axial T2-weighted MR image (A) shows the tumour at the right internal iliac lymph node level (yellow arrow). The lesion has no flow void, different from the one observed in the iliac arteries (white arrow). DWI sequence (B) reveals restricted diffusion. Pre-contrast T1-W image confirms the solid nature of the lesion, with heterogeneous hypervascular enhancement depicted at dynamic arterial phase (D); an internal area of low enhancement is attributed to necrosis after arterial embolisation. DWI, diffusion-weighted images.

Figure 4

(Upper images) H&E stain: lymph node parenchymal involvement by spindle-shaped arranged cells in storiform pattern: 100× and 200×, respectively. (Bottom-left) Immunohistochemical analysis: positive for smooth muscle actin. (Bottom-right) Immunohistochemical analysis: positive for podoplanin.

Figure 5

S-100 protein by immunohistochemistry. The neoplastic cells are negative. Only dendritic cell in the centre of the field is positive. 400×.