PMC5383940_01
X-rays of the hip showing an osteolytic tumor at the site of the fracture (left side)
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Fig1
An X-ray radiograph has been performed and revealed at the traumatic site, a relatively well-limited trochanteric osteolityc lesions at the fracture's site (Fig. 1).
A dense infiltrate composed of numerous plasma cells, lymphocytes, neutrophils, eosinophils, macrophages and prominent figures of emperipolesis (a). Higher magnification showing a figure of emperipolesis. A huge cell with abundant pink cytoplasm, engulfing plasma cells, lymphocyts and neutrophils is seen (b)
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Fig2
After treatment with 10% nitric acid (decalcification), the histological examination of the submitted bone biopsies showed a dense inflammatory infiltrate destroying the bone tissue (Fig. 2a).
Mononuclear cells stained strongly positive for CD1a, whereas giant cells with emperipolesis stained negative (black arrows) (a). Some CD1a + cells are round-shaped with oval nuclei, reminiscent to RDD-cells ("Blanks cells" or transitional cells) (b)
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Fig3
At imunohistochemistry, many mononucleated cells show intense membraneous expression of CD1a, whereas giant multinucleated cells with emperipolesis stain negative (Fig. 3a). Also, some CD1a positive cells are round-shaped with oval nuclei, and a large cytoplasm, morphologically reminiscent of RDD cells (Fig. 3b).
S-100 protein is strongly expressed by histiocytes of both RDD and LCH components
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Fig4
However, both cell types express CD68 and S-100 protein (Fig. 4).