Objective:To investigate the clinicopathological and genetic characteristics of monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL).Methods:The forty-two MEITL cases diagnosed in the Department of Pathology, Ruijin Hospital affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China from 2016 to 2022 was retrospectively analyzed. Clinical data were collected, and follow-up was performed. Morphological characteristics were observed. Immunohistochemistry, Epstein-Barr virus (EBV) in situ hybridization, clonal rearrangement analysis of T-cell receptor (TCR) genes, and targeted next-generation sequencing (NGS) were performed.Results:Among the 42 patients (male/female ratio of 2.8∶1.0), the age range was 32-77 years with a median age of 59.5 (52.0-65.0) years. Grossly, the tumors were presented as ulcerative or exophytic lesions, with a maximum diameter of 2-18 cm. There were 34 cases with a single lesion and 8 cases with more than 1 lesion. The tumor cells in all 42 cases were relatively monotonous in histology and small or medium in size. They had round or oval nuclei, moderately pale or clear cytoplasm, evenly distributed nuclear chromatin, inconspicuous nucleoli, and frequent mitotic figures. In one of the cases, there were moderately large cells, vacuolated nuclei, and clear nucleoli. Lymphoepithelial lesions were observed in 36 (85.7%) of the 42 cases, tumor necrosis in 4 (9.5%) cases, scattered eosinophils and/or plasma cell infiltration in the background in 9 (21.4%) cases, and a "starry sky" phenomenon in 1 (2.4%) case. The tumor cells in all cases exhibited high expression of CD3, CD2, CD7, CD8, CD56, TIA1, Granzyme B, and Perforin, while some also expressed CD4 (5/41, 12.2%), CD5 (3/41, 7.3%), CD20 (4/41, 11.9%), CD79α (2/37, 5.4%), and CD30 (1/34, 2.9%). The Ki-67 proliferation index ranged from 40% to 90%. EBER in situ hybridization tests were negative in all cases. TCR gene clonal rearrangement was detected in 96.4% (27/28) of the tested cases. Targeted NGS revealed commonly mutated genes including SETD2, STAT5B, JAK3, TP53, and CREBBP. The primary treatment was chemotherapy, with 2 cases undergoing autologous hematopoietic stem cell transplantation. Follow-up information was obtained for 29 cases, with a follow-up period of 1-73 months. The mortality was 93.1% (27/29).Conclusions:MEITL is a rare and highly aggressive peripheral T-cell lymphoma. Its clinical manifestations are diverse, and diagnosis primarily relies on a comprehensive assessment of pathological morphology, immunohistochemical profiles, and EBV infection status, supplemented by genetic testing if necessary. At present, there is no effective treatment, and its overall prognosis is poor.

Nonspecific peripheral T-cell lymphoma (PTCL-NOS) combined with pure red cell aplasia (PRCA) is reported by only few in China. This article described a patient with PTCL-NOS who presented with severe anemia as the initial symptom, accompanied by multiple lymphadenopathy. Laboratory tests confirmed decreased red blood cell count and reticulocyte proportion, markedly reduced bone marrow red blood cell proliferation, and markedly increased proportion of bone marrow CD3 +CD8 + T lymphocytes. On lymph node pathology examination, immunohistochemistry was consistent with PTCL-NOS, with positive TCRβ gene rearrangement. First-line chemotherapy with four courses of ECHOP regimen led to significant reductions in lymph node size, partial remission on whole-body computed tomography evaluation, normalization of hemoglobin and bone marrow hematopoietic erythroid proliferation, and absence of CD3 +CD8 + T lymphocytes in bone marrow. Currently, the patient remains to have good prognosis with maintenance oral lenalidomide.

Objective:To investigate the clinicopathological and genetic characteristics of monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL).Methods:The forty-two MEITL cases diagnosed in the Department of Pathology, Ruijin Hospital affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China from 2016 to 2022 was retrospectively analyzed. Clinical data were collected, and follow-up was performed. Morphological characteristics were observed. Immunohistochemistry, Epstein-Barr virus (EBV) in situ hybridization, clonal rearrangement analysis of T-cell receptor (TCR) genes, and targeted next-generation sequencing (NGS) were performed.Results:Among the 42 patients (male/female ratio of 2.8∶1.0), the age range was 32-77 years with a median age of 59.5 (52.0-65.0) years. Grossly, the tumors were presented as ulcerative or exophytic lesions, with a maximum diameter of 2-18 cm. There were 34 cases with a single lesion and 8 cases with more than 1 lesion. The tumor cells in all 42 cases were relatively monotonous in histology and small or medium in size. They had round or oval nuclei, moderately pale or clear cytoplasm, evenly distributed nuclear chromatin, inconspicuous nucleoli, and frequent mitotic figures. In one of the cases, there were moderately large cells, vacuolated nuclei, and clear nucleoli. Lymphoepithelial lesions were observed in 36 (85.7%) of the 42 cases, tumor necrosis in 4 (9.5%) cases, scattered eosinophils and/or plasma cell infiltration in the background in 9 (21.4%) cases, and a "starry sky" phenomenon in 1 (2.4%) case. The tumor cells in all cases exhibited high expression of CD3, CD2, CD7, CD8, CD56, TIA1, Granzyme B, and Perforin, while some also expressed CD4 (5/41, 12.2%), CD5 (3/41, 7.3%), CD20 (4/41, 11.9%), CD79α (2/37, 5.4%), and CD30 (1/34, 2.9%). The Ki-67 proliferation index ranged from 40% to 90%. EBER in situ hybridization tests were negative in all cases. TCR gene clonal rearrangement was detected in 96.4% (27/28) of the tested cases. Targeted NGS revealed commonly mutated genes including SETD2, STAT5B, JAK3, TP53, and CREBBP. The primary treatment was chemotherapy, with 2 cases undergoing autologous hematopoietic stem cell transplantation. Follow-up information was obtained for 29 cases, with a follow-up period of 1-73 months. The mortality was 93.1% (27/29).Conclusions:MEITL is a rare and highly aggressive peripheral T-cell lymphoma. Its clinical manifestations are diverse, and diagnosis primarily relies on a comprehensive assessment of pathological morphology, immunohistochemical profiles, and EBV infection status, supplemented by genetic testing if necessary. At present, there is no effective treatment, and its overall prognosis is poor.

Nonspecific peripheral T-cell lymphoma (PTCL-NOS) combined with pure red cell aplasia (PRCA) is reported by only few in China. This article described a patient with PTCL-NOS who presented with severe anemia as the initial symptom, accompanied by multiple lymphadenopathy. Laboratory tests confirmed decreased red blood cell count and reticulocyte proportion, markedly reduced bone marrow red blood cell proliferation, and markedly increased proportion of bone marrow CD3 +CD8 + T lymphocytes. On lymph node pathology examination, immunohistochemistry was consistent with PTCL-NOS, with positive TCRβ gene rearrangement. First-line chemotherapy with four courses of ECHOP regimen led to significant reductions in lymph node size, partial remission on whole-body computed tomography evaluation, normalization of hemoglobin and bone marrow hematopoietic erythroid proliferation, and absence of CD3 +CD8 + T lymphocytes in bone marrow. Currently, the patient remains to have good prognosis with maintenance oral lenalidomide.

Objective:To explore the clinicopathological characteristics of primary bladder mucosal-associated lymphoid tissue extranodal marginal zone lymphoma (MALToma).Methods:A retrospective case series study was conducted. The clinicopathological data of 9 primary bladder MALToma patients diagnosed and underwent transurethral resection of bladder tumors at the Fujian Provincial Hospital, Zhangzhou Municipal Hospital, Mindong Hospital of Ningde City, Zhangzhou Second Hospital and Fuzhou Taijiang Hospital from December 2008 to December 2021 were collected. Paraffin-embedded surgical specimens were collected for HE staining, immunohistochemical staining and genetic testing, the clinicopathological characteristics of patients were summarized, and the literature was reviewed.Results:Of the 9 cases, 8 were female and 1 was male, the age was (59± 11) years old (range: 39-74 years old). Two cases had 3 lesions, 3 cases had 2 lesions, and 4 cases had single lesion. The maximum diameter of the mass was (3.2±1.9) cm (range: 0.3-7.0 cm). The follow-up time was 6-127 months, 4 cases lost to follow-up, 4 cases were disease-free survival, and 1 case was survival with tumor. Pathomorphologically, the bladder tissue consisted of diffusely infiltrating small-to-medium sized lymphocytes, with moderate amounts of pale-staining cytoplasm, without obvious nucleoli, some of them were translucent, and the mitosis was rare. Large cell proliferation in some areas was observed in 1 case, with prominent nucleoli and mitotic figures. Tumor cells in all 9 patients expressed CD20; bcl-2, CD43 and CD38 were positive in some cells in 4 cases, and CD138 was positive in a few cells in 2 cases; κ was positive in 4 cases, and scattered positive in 5 cases; λ was positive in 4 cases, and scattered positive in 5 cases. B-cell receptor gene clonal rearrangement was positive in all 8 cases who underwent the assay. No break-apart signal was observed in all 6 cases who underwent the fluorescence in situ hybridization assay with MALT1 gene segregation probe.Conclusions:Primary bladder MALToma is a rare low-grade B-cell lymphoma that is more commonly found in elderly women. There is no abnormal change in MALT1 gene.

Objective:To investigate the clinicopathologic features, differential diagnosis, immunohistochemical profiles and molecular characteristics of primary extraskeletal osteosarcoma (ESOS).Methods:Ten cases of ESOS diagnosed and treated in Fujian Provincial Hospital, Fuzhou, China from January 2003 to January 2019 were collected and subjected to immunohistochemical staining and molecular analyses. The patients were followed up by telephone interview. Relative literature was also reviewed to assess the characteristics of this tumor.Results:The ten cases occurred in 3 women and 7 men, aged from 36 to 85 years (median, 60 years). The sizes of these tumors ranged from 5.5 to 17.5 cm (median, 11.0 cm). Histologically, at low magnification, the tumors were nodular, leafy and lobulated. They were composed of spindle cells, neoplastic osteoid cells, and cartilage tissues, with unequally-proportional mixture of these components. The three components intermingled with each other. Immunohistochemistry profiling showed that the tumor cells were positive for SATB2 (9/9), while α-SMA (4/10) and EMA (1/10) stains were focally positive. Ki-67 proliferation index was 10%?50%. Desmin, CD68, S-100 protein, SOX10, HMB45, CD117, DOG1, CD34, CKpan, GATA3 and PAX8 stains were negative. MDM2/CDK4 gene amplification signals were not detected in the 6 cases (0/6), which were subjected to the FISH. The SSX18 break-apart signal and the C-KIT and PDGFR-α mutations were not detected (0/5 and 0/3, respectively). Conclusions:Primary ESOS is an extra-osseous osteogenic tumor. The diagnosis is mainly dependent on clinical, radiological and pathological characteristics. Immunohistochemistry and molecular profiling are helpful for making the correct diagnosis.

Objective:To investigate the clinicopathological features, diagnosis, differential diagnosis and immunohistochemical (IHC) characteristics of paraganglioma of urinary bladder (PUB).Methods:The clinical and pathological data of 23 cases of PUB were collected at the Second Affiliated Hospital of Fujian Medical University (7 cases); Fujian Provincial Hospital (8 cases); Fujian Medical University Union Hospital (6 cases); and First Affiliated Hospital of Fujian Medical University (2 cases) from May 2010 to November 2018. IHC staining for CK, GATA3, CD56, Syn, CgA, S-100 protein, HMB45, SDHB, OCT3/4 and Ki-67 was done using EliVision method; and the relevant literature was reviewed.Results:There were 14 women and 9 men, aged ranged from 21 to 73 years (median 51 years). Clinically, patients presented with headache, vertigo, palpitation, hypertensive crisis during micturition, hypertension, blurred vision, gross hematuria and paroxysmal pallor. The tumor sizes ranged from 0.9 to 6 cm (mean2.5 cm). Macroscopically, most tumors were exophytic and well delineated within the lamina propria or muscularis propria. The tumors were firm and nodular and showed grayish-tan cut surface. Histologically,the tumor growth pattern was expansive or showed interpenetrating infiltrative growth within the lamina propria or muscularis propria; the tumor cells were typically arranged in distinctive nests (Zellballen) with organoid arrangement; pseudo-rosette were seen in some cases. The cells were rounded or polygonal and had rich, acidophilic or amphophilic cytoplasm and may contain pigmented granules and vacuoles; the nuclei were central or eccentric, with small nucleoli, although occasionally some nuclei were pleomorphic and hyperchromatic. Spindled sustentacular cells could be seen around the nests of tumor cells in some cases. There were abundant vessels that were fissure-like, hemangioma-like or dilated. By IHC, the tumor cells were positive for GATA3 (2/23), OCT3/4 (2/23), CD56 (22/23), Syn (23/23), CgA (22/23), S-100 (sustentacular cell, 23/23) and SDHB (23/23); and negative for CK and HMB45; Ki-67 index was 1%-5%. At follow-up, there was no recurrence or metastasis in 18 cases.Conclusions:The diagnosis of PUB relies on the morphologic and IHC features; but there may be histomorphologic heterogeneity. The most important differential diagnosis is invasive urothelial carcinoma. The tumor cells may show aberrant cytoplasmic expression of OCT3/4; there is no clear correlation between SDHB and OCT3/4 expression in the group.

Objective:To investigate the clinicopathological features, diagnosis, differential diagnosis, and molecular alterations of malignant gastrointestinal neuroectodermal tumor (MGNET).Methods:Four cases of MGNET were collected at Fujian Provincial Hospital, from July 2013 to January 2019. H&E and immunohistochemical staining were retrospectively evaluated, together with genetic mutation analysis of EWSR1. The relevant literature was systematically reviewed.Results:There were two male and two female patients, with an age range of 34-81 (median 57) years. Tumor sizes ranged from 5-9 (median 6.8) cm. Microscopy showed diffuse and flaky growth of tumor cells, some of which were small and round. The tumor cells were arranged in solid, flaky, nested or pseudoadenoid patterns. The tumor cells were epithelioid, oval, short spindled, or small, with round or oval nuclei. The cytoplasm was eosinophilic or clear. Osteoclast-like multinucleated giant cells were scattered focally. Mitosis was about (2-10)/10 HPF. Immunohistochemically, the tumor cells were positive for S-100 protein (4/4), SOX10 (4/4), Syn (2/4), INI1 (4/4), H3K27Me3 (4/4) and vimentin (4/4). Ki-67 index was 15%-90%. Gene mutation detection confirmed EWSR1 mutation in all four cases, and C-KIT/PDGFRα genes were not mutated in two cases.Conclusions:MGNET is a rare high grade malignant soft tissue tumor. The diagnosis is based on clinicopathological, immunophenotypic, and molecular pathology features. The primary treatment for MGNET is complete surgical excision and chemotherapy; the prognosis is poor.