PMC6953532_01
Injected computed tomography of the abdomen after bilateral ureteral stent insertion: arrows showing the infiltration of the right (a) and left (b) kidneys by a homogeneous tissue enclosing the pelvis, signs of retroperitoneal fibrosis. No characteristic "hairy kidney" appearance and no signs of aortic involvement.
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An injected thoraco-abdominopelvic CT scan showed infiltration of both the kidney sinus by a homogeneous tissue enclosing the pelvis and the proximal ureters as well as the vascular structures of the renal hilum suggestive of retroperitoneal fibrosis (Figure 1).
Histopathological finding of the renal specimen resected by CT-guided Tru-Cut biopsies: hematoxylin-eosin staining revealed a diffuse proliferation of histiocytes associated to lymphocytic and monocellular invasion, as well as important fibrotic involvement ((a) original magnification x100). Immunochemistry demonstrated that histiocytes were strongly positive for CD68 (b) and negative for CD1a antigen (c) ((b, c) original magnification x400). Touton-like multinucleated giant cells (arrowheads) are visible on both CD68 (b) and hematoxylin-eosin staining ((d) original magnification x400).
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Tru-Cut biopsies of the left thickened renal pelvis were obtained. The diagnosis of ECD was confirmed by pathology, with signs of retroperitoneal fibrosis, as well as histiocytosis associated to lymphocytic and monocellular invasion (Figure 2(a)). On immunohistochemical staining, histiocytes were CD68 positive (Figure 2(b)) but negative for CD1a antigen (Figure 2(c)). Multinucleated giant Touton cells were also visible (Figures 2(b) and 2(d)).
18-Fluorodeoxyglucose positron emission tomography (coronal views): 18FDG-PET scan showing FDG-avid sclerotic bone lesions in the distal femoral metadiaphysis bilaterally (a) as well as the right iliac bone involvement (b).
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An uptake of 18-FDG was also notable in the fractured right iliac bone (Figure 3).