case_images: PMC11730790_01
case_images: A: Cytological examination of the bone marrow aspiration showing massive infiltration by large pleiomorphic cells with some of them displaying the morphological features of "hallmark" cells that are typically associated with anaplastic large cell lymphomas [x1000, May Grunwald-Giemsa [MGG] stain]. B: Histiocytic neoplastic proliferation with some cells displaying cytological atypias including spindle shape or emperipolesis images [x1000, May Grunwald-Giemsa [MGG] stain]. C: Representative image of a multinucleated histiocyte [double arrowheads] in the bone marrow aspiration displaying emperipolesis with the cytoplasmic engulfment of two large lymphomatous cells [single arrow heads], and one small normal lymphocyte [arrow]. One of the lymphomatous cells shows a cytoplasmic engulfment of an erythrocyte [x1000, May Grunwald-Giemsa [MGG] stain]. D: Representative image of two histiocytic cells [x1000, May Grunwald-Giemsa [MGG] stain]. E: FISH analysis showing the same cells seen in Panel C : each of the two lymphomatous cells [single arrow heads] display one red signal illustrating the monosomy 13 identified on karyotype and three green signals for the centromeric 12 probes. Multiple copies of the same pattern are shown within the nuclei of the multinucleated histiocyte [double arrowheads], while the small lymphocyte is displaying a normal pattern with two green and two red signals [arrow] [x1000]. F: FISH analysis on the same two histiocytic cells [from panel D]: one cell shows loss of one chromosome 13 signal and three signals for chromosome 12 while the other cell exhibits a duplication of the same pattern [x1000]
case_images: 13000_2025_1597_Fig1_HTML.jpg
case_images: PMC11730790_01_13000_2025_1597_Fig1_HTML.jpg
case_images: Fig1
case_images: HLADR-] were associated with numerous histiocytes showing cytological atypias including gigantism, multinucleation, spindle shape, and emperipolesis images [Fig. 1B]. FISH analyses were negative for ALK and DUSP22 rearrangement, but confirmed that both malignant cell types shared, at least, monosomy 13 and the supernumerary marker chromosome identified as a partial chromosome 12 [Fig. 1C-F].
case_images: Flow cytometry plots showing lymphomatous cells in red and histiocytes in dark blue. Lymphoma cells expressed the following immunophenotype: CD30 + CD4+/- CD56- CD13- HLADR- CD3- CD7+/- CD14-. Histiocytes expressed the following immunophenotype:CD30- CD4 + + CD56 + + CD13 + + HLADR + + CD3- CD7- CD14-
case_images: 13000_2025_1597_Fig2_HTML.jpg
case_images: PMC11730790_01_13000_2025_1597_Fig2_HTML.jpg
case_images: Fig2
case_images: Histiocytes expressed an aberrant immunophenotype by flow cytometry [CD2- CD3- CD4 + + CD5- CD7- CD8- CD13 + + CD14- CD33- CD30- CD56 + + HLADR+] [Fig. 2]. Histopathological examination of the BMB [Fig. 3] mainly identifies a few areas of infiltration of the marrow by lymphoma cells with a predominant intrasinusoidal localization.
case_images: Histopathological features of the bone marrow biopsy BMB: Some areas show diffuse infiltration of the marrow by lymphoma cells with a predominant intrasinusoidal location and occasional images of emperipolesis or hemophagocytosis [hematoxylin eosin A [H&E], original magnification x200]. Lymphoma cells are strongly positive for CD30 B [Immunohistochemical [IHC] staining, original magnification x200]. Other marrow spaces show a complete replacement of the hematopoietic tissue by a neoplastic proliferation of atypical histiocytes within a fibrous stroma C: [H&E], original magnification x100]. Malignant histiocytes are strongly positive for CD68 D and CD163 E [IHC staining, original magnification x100]. The histiocytic area shows no CD30 expression F [IHC staining, original magnification x200]
case_images: 13000_2025_1597_Fig3_HTML.jpg
case_images: PMC11730790_01_13000_2025_1597_Fig3_HTML.jpg
case_images: Fig3
case_images: Histiocytes expressed an aberrant immunophenotype by flow cytometry [CD2- CD3- CD4 + + CD5- CD7- CD8- CD13 + + CD14- CD33- CD30- CD56 + + HLADR+] [Fig. 2]. Histopathological examination of the BMB [Fig. 3] mainly identifies a few areas of infiltration of the marrow by lymphoma cells with a predominant intrasinusoidal localization.