PMC7425660_01
Case 1. Before histological diagnosis, flow cytometry analysis detected an aberrant T-cell population in peripheral blood (PB) (shown in blue). The aberrant T-cells were identified in the area of lymphocytes by using the Forward versus Side Scatter (FSC vs SSC) gating (panel A) and CD45 versus SSC (panel B) gating. These cells were positive for CD3 (dim) and CD4 (C) and negative for CD8 (D). Of note, CD10 was expressed by these cells (E). Lymph node biopsy showed typical morphological (hematoxylin and eosin, H&E) ((F); original magnification x20) and immunohistochemical findings with positivity for CD5 ((G); original magnification x10), CD10 ((H); original magnification x20) and negativity for CD20 ((I); original magnification x10). Bone marrow biopsy at diagnosis (J) showed negativity for CD3 ((K); original magnification x20), CD4 ((L); original magnification x20) and CD20 ((M); original magnification x20).
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T-cells with decreased CD3 expression (CD3+ dim) (Figure 1A-D). This population also showed the positive expression of the T-cells markers CD7, CD2 and CD5 and the negative expression for the 24 rearrangements of TCRVbeta repertoire tested. Furthermore, this T-cell population also expressed CD10 (Figure 1E). The LN displayed a prominent proliferation of high endothelial venules, an increase of dendritic cells and a diffuse infiltration of a mixed population of eosinophils, neutrophils, plasma cells, with medium- to small-sized atypical lymphoid cells (Figure 1F) positive for CD3, CD4, CD5 (Figure 1G), CD10 (Figure 1H) and CD7 (focal), and negative for CD20 (Figure 1I), CD79a and CD30. Notably, morphologic evaluation of BM smears and bone marrow biopsy (BMB) was not able to detect any BM infiltration (Figure 1J-M).
Case 1. Bone marrow (BM) biopsy at progression showing morphological (hematoxylin and eosin, H&E) lymphoid cells (A); original magnification x20) negative for CD5 (B); original magnification x20) and positive for CD20 (C); original magnification x20), CD30 (D); original magnification x20). Immunohistochemical positivity for EBV (by using Monoclonal Mouse Anti-Epstein-Barr Virus, LMP) of diffuse large B-cell lymphoma in lymph node biopsy ((E); original magnification x20) and BM aspirate ((F); original magnification x10).
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The LN biopsy of the initial AITL-diagnosis and the BMB involved by DLBCL were tested by immunohistochemistry for Epstein-Barr Virus (EBV) (by using DAKO Monoclonal Mouse Anti-Epstein-Barr Virus, LMP, CS.1-4 clone): both samples resulted positive (Figure 2E and F). The patient died in December 2017 for a progressive multiorgan failure.
PMC7425660_02
Case 2. PET-CT scan (A) showed voluminous subcutaneous thickenings in dorsal and lumbar regions (circled areas). Hematoxylin and eosin (H&E) (B); original magnification x20) on the biopsies of backside and scalp cutaneous lesions showed infiltration of small and medium-sized lymphoid elements, positive for CD3, CD4, CD5 (C-E), original magnification x10) and negative for CD8 (F), original magnification x10). FCM immunophenotyping on bone marrow aspirate (G-K) showed pathological T cells positive for CD3, CD4, CD7 (dim) and CD5 (in green color), and negative for CD45, CD8 and TdT.
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PET-CT scan (Figure 3A) demonstrated a faint hyperaccumulation of the tracer in correspondence of the voluminous subcutaneous thickenings in the left parietal, right dorsal and homolateral lumbar regions and an absence of uptake in a nodulariform thickening in the subcutaneous tissue of the right scapular region and in the numerous LNs in bilateral inguinal and axillary regions and in Barety's space. Cutaneous biopsies of backside and scalp lesions showed infiltration, diffuse and subtotal, of small and medium-sized lymphoid elements, with pleomorphic nuclei, extended to the superficial and deep reticular dermis, in the absence of epidermotropism (Figure 3B). These cells were found to be CD3+, CD4+, CD5+, CD8- (Figure 3C-F), CD56-, CD7-, CD57-, CD30-, CD20- with Ki67 cell proliferation index about 20%.
PMC7425660_03
Case 3. Bone marrow (BM) aspirate showed a widespread lymphoid infiltration, predominantly small "mature" lymphocytes with very rare nucleoli (A and B). Examples of immunophenotypic features seen on peripheral blood samples of the reported case of concomitant T-PLL and MBL. Neoplastic T cells are in purple and express CD4 (D and lack CD8 (E) and CD34 (F). They lack surface CD3 expression, but present cytoplasmic CD3 (G). CD45 was expressed by only a subset of pathological T lymphocytes (C). B-CCL/SLL cells (in yellow) on the PB sample present typical co-expression of CD19 and CD5 (H). Trephine BM biopsy of the reported case of concomitant T-PLL and MBL displayed small and sometimes medium-size lymphoid elements (Q), original magnification x20) with predominantly T phenotype: CD3+ (I), original magnification x20), CD4+ (J), original magnification x20), CD5+ (K), original magnification x20), CD8- (L), original magnification x20), CD20- (M), original magnification x20), CD56- (N), original magnification x20), CD79- (O), original magnification x10) and CD57- ((P), original magnification x20).
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BM aspirate showed a widespread lymphoid infiltration, predominantly small "mature" lymphocytes with very rare nucleoli, representing about half of the total cells (Figure 4A and B). T-cells were mixed with a small population of clonal B lymphocytes (3,1% of leukocytes in PB, 2.2% of all nucleated cells in BM), that expressed CD19, CD5, CD20 (dim), CD23, CD43, CD200, sIgkappa (dim), with a D'Arena Score of 4 (Figure 4C-H). Trephine BM biopsy showed two nodular aggregates of small and sometimes medium-sized lymphoid elements with predominantly T phenotype (CD57-, CD8-, CD5+, CD3+, CD4+, CD56-), mixed with rare CD20+, CD79alpha+ small B lymphocytes (Figure 4I-Q).