Splenic Rupture and Malignant Mediterranean Spotted Fever

International audienc

Expansion of Regulatory T Cells in Patients with Langerhans Cell Histiocytosis

Frederic Geissmann and colleagues find that Langerhans cell accumulation in Langerhans cell histiocytosis results from survival rather than uncontrolled proliferation, and is associated with the expansion of regulatory T cells

A t(17;22)(q21;q12) with partial ETV4 deletion in a soft tissue Ewing sarcoma

Cytogenetic analysis of a lumbar soft tissue Ewing sarcoma (ES) in a 7-month-old female child showed a t(17;22)(q21;q12), a rare translocation leading to an EWSR1-ETV4 chimeric transcript. These findings were confirmed by reverse transcription-polymerase chain reaction (RT-PCR) and fluorescence in situ hybridization (FISH) techniques. The breakpoints were characterized by direct sequencing of the chimeric fusion gene. Tumor genotyping using the Affymetrix Genome-Wide Human single nucleotide polymorphism (SNP) array 6.0 Genechip identified deletions of both chromosomal regions involved in the translocation, resulting in partial deletion of ETV4, but an uninvolved EWSR1 gene. The creation of a fusion between EWSR1 and an ETS family gene consecutive to a chromosomal translocation is characteristic of the Ewing family of tumors (EFT). This is the first report of a deletion involving the two breakpoints in an EWS-ETS translocation. To date, only two cases of t(17;22)(q21;q12) in Ewing sarcoma have been reported, with no associated deletion. Interestingly, both cases had also occurred in soft tissue tumors, which are less common than their bone-involving counterparts

Proliferating Cells in LCH Granuloma are Mostly Endothelial Cells, Fibroblasts, and T Cells

<div><p>Paraffin-embedded and frozen sections were stained with antibodies against Ki-67 (which label proliferating cells), CD1a (LCs), CD3 (T cells), CD20 (B cells), CD68, CD31, and CD34 (endothelial cells).</p> <p>(A) Double immunostaining of paraffin-embedded section from LCH eosinophilic granulomas with anti-Ki-67 Ab, (brown nuclear staining) and with anti-CD1a Ab (upper images, blue staining) or anti-CD3 Ab (lower images, blue staining). Open arrowheads indicate double-stained cells, black arrowheads indicate Ki-67⁺ cells with an endothelial morphology.</p> <p>(B) Histogram represents percentage of CD1a⁺ cells and of CD3⁺ cells labeled with Ki-67 (<i>n</i> = 15).</p> <p>(C) Histogram represents percentage of proliferating cells (Ki-67⁺) that express CD1a, CD3, CD20, or CD68 (<i>n</i> = 15).</p> <p>(D) Histogram represents percentage of proliferating cells (Ki-67⁺) that are endothelial cells, interstitial cells (fibroblasts), and other types based on morphological examination.</p> <p>(E) Immunolabeling of blood vessels on paraffin-embedded section from LCH eosinophilic granulomas with CD34 (left) and CD31 (right) antibodies.</p> <p>(F) Proliferating Ki-67⁺ cells (brown nuclear staining) with a fibroblast-cell morphology in an eosinophilic granuloma.</p></div

Polyclonal T Cells Infiltrate LCH Granuloma in Close Contact with LCs

<div><p>(A) Double immunohistochemical labeling of frozen sections from an eosinophilic granuloma with anti-CD3 (brown) and anti-CD1a antibodies (blue).</p> <p>(B) T cell receptor gamma rearrangement was determined on the DNA extracted from frozen biopsies from four patients. Fluorescent profiles for Vgfl/Vg10 PCR using fluorescent Jg primers (JgP, red; Jg1/2, green; JgP1/2, blue) are shown; all the biopsies display a polyclonal profile in comparison to polyclonal and monoclonal positive controls.</p></div