PMC10273903_01
Coronal and axial images from MR urogram imaging demonstrating diffuse perinephric and urothelial soft tissue thickening and enhancement (white arrowheads).
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F1
A pelvic MRI urogram for bladder cancer surveillance revealed bilateral perinephric fat stranding with diffuse perinephric and urothelial soft tissue thickening (Fig. 1).
Photomicrographs. a-d Hematoxylin and eosin-stained sections from the CT-guided peri-renal mass biopsy showing fibroadipose tissue infiltrated by clusters of histiocytes in a background of polymorphous inflammatory infiltrate with scattered Touton giant cells (magnification: a. x200, b and c. x400). d, e Immunochemistry staining showing strong and diffuse positivity for CD68 and BRAFV600E, respectively (x400). f Negative staining for CD1a (x400).
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F2
The patient underwent a CT-guided core biopsy of this perinephric lesion which revealed mature fibroadipose soft tissue featuring a population of relatively bland-appearing histiocytes characterized by abundant foamy cytoplasm (Fig. 2).
Photomicrographs. a-d Sections from the shoulder biopsy show skin with a diffuse infiltrate of cells that are both spindled and rounded with variable amounts of cytoplasm. Numerous admixed neutrophils are seen (a-c). Rare Touton giant cells are present (c) (magnification: a. x40, b. x200, c. x200). d, e Immunocytochemical stains are performed and show variable positivity for CD68 and factor XIII (magnification: d. x200, e. x200). f BRAF stain is negative (magnification: f. x200).
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F3
Immunohistochemical staining (Fig. 3) revealed the histiocytes exhibiting a CD68 (+), CD1a (-), langerin (-), and S100 (-) immunophenotype, along with positivity for a BRAF VE1 (V600E) stain.