PMC10331127_01
Imaging examination: CTU suggested right kidney enlargement (A-D), multiple hyperdense nodules (B, D), the contrast-enhanced urogram showed significant enlargement and dilatation of the right kidney and the upper segment of the right ureter (C). The appendix also thickened with mild enhancement (E, F), with a hypodense lumen without enhancement (F). IVU showed no development of the right kidney, right kidney stone, and normal excretion of the left kidney (G). (The giant right kidney was showed by red arrows, the kidney stone was showed by white arrows, and the appendix was showed by yellow arrows.).
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Working diagnoses were i) right ureteral wall thickening, suggestive of inflammatory changes, multiple stones in the right kidney, and severe hydronephrosis of the right kidney; and ii) abnormal appendiceal density, suggestive of a mucinous tumor ( Figures 1A-F ). Intravenous urography (IVU) showed no development of the right kidney, right kidney stones, normal excretion of the left kidney, and scoliosis ( Figure 1G ).
Gross appearance: The appendix was swollen and thickened, filled with mucus (black arrow) (A). The right kidney was found: dilated renal pelvis, thin renal parenchyma, multilocular and dilated renal cysts with abundant gelatinous mucus and cauliflower-like masses in the renal pelvis and calyces (yellow arrow) (D). Microscopic overview of the appendix (B, C) and the right kidney (E, F). [Hematoxylin-eosin staining, x100 (B, E), x400 (C, F)].
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The appendix was completely removed, and upon specimen collection, a great amount of mucus was seen in the appendix cavity ( Figure 2A ). AMN (LAMN) and the incisal margin of the appendix was negative ( Figures 2B, C ). As the patient decided to defer further treatment for the right kidney, she was discharged for rest and recovery. When the kidney was sliced open, the following were found: dilated renal pelvis, thin renal parenchyma, multilocular and dilated renal calyces with abundant gelatinous mucus, multiple stones measuring approximately 20 x 15 x 9 mm and three cauliflower-like masses measuring approximately 20 x 18 x 8 mm in the renal pelvis, and calyces ( Figure 2D ). Postoperative pathology suggested a high-grade mucinous neoplasm of the renal pelvis and mucin residing partly in the interstitium of the cyst walls, without the involvement of the ureter, blood vessels, perirenal lymph nodes, or perirenal fat ( Figures 2E, F ).
Immunohistochemistrical (IHC) analysis (A-F): (A) CDX2 (+), (B) Villin (+), (C) GATA3(-), (D) P63 (-), (E) CK7 (-), (F) Ki-67 (about 60%+), indicated features of appendiceal mucinous neoplasm metastasis to the renal pelvis. (x100).
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Immunohistochemistrical results showed that CDX2 (+), Villin (+), GATA3(-), P63 (-), CK7 (-) and Ki-67 (about 60%+), indicated features of appendiceal mucinous neoplasm metastasis to the renal pelvis ( Figures 3A-F ).