Angioimmunoblastic T-cell lymphoma (AITL) is a unique form of peripheral T cell lymphoma (PTCL), accounting for 18.5% of all PTCLs. According to the WHO classification revised in 2016, AITL belongs to the nodular PTCL with a T follicular helper (Tfh) cell phenotype. AITL is characterized as B-symptoms (fevers, unintentional weight loss, and/or night sweats), generalized lymphadenopathy and autoimmune-like manifestations. Most AITLs are in advanced stages (III/IV) at the time of diagnosis, plausibly leading to adverse prognosis due to atypical clinical and laboratory results . Hypereosinophilia is seen in one-third to one-half of the AITL cases and causes great difficulty in making diagnosis[5, 6]. In the past few decades, AITL's diagnostic capabilities have been continuously improved with the development of next-generation sequencing technologies and the development of AITL molecular markers. AITL genomic abnormalities are highly disease-specific and the ras homology family member A (RHOA) mutation is one of the most frequent recurrent mutations. RHOA mutations in AITL invariably encode p.Gly17Val. In this study, we identified a novel RHOA mutation encoding P. Ala161Glu in a patient with AITL.
A 57-year-old female was admitted to hospital on 6 April 2020 with hypereosinophilia for 3 years and abdominal discomfort for 8 months. Three years earlier, she had been treated at another hospital with imatinib plus prednisone for idiopathic eosinophilic hyperplasia. The regimen was initially effective but the eosinophil counts rebounded as prednisone was stopped. Physical examination showed that the upper abdomen was slightly tender on palpation. No skin lesions were observed. Laboratory data showed that eosinophil count was 33.67×109/L. Lactate dehydrogenase (LDH) was slightly elevated (356U/L, literature upper limit 250). Serum total immunoglobulin E (IgE) was elevated (315.149 KIU/L, reference upper limit 100). Hepatitis B Virus (HBV) testing showed that HBsAg, anti-HBe and anti-HBc were all positive but no HBV-DNA was detected. EBV-DNA was also undetectable. Repeated examinations of stool specimens for ova and parasites were negative. Serum allergens and parasites were negative. Lung radio-graphs was normal. Bone marrow examination showed significantly iincreased eosinophils (Fig. 1A, B, C, D). The immunoglobulin heavy chain (IGH) and the T-cell receptor (TCR) gene rearrangements were negative based on PCR analysis of the bone marrow. Gene detection by Next Generation Sequencing (NGS) in bone marrow indicated that JAK2-V617F, platelet derived growth factor receptor alpha (PDGFRα), platelet derived growth factor receptor alpha belta (PDGFRβ) and fibroblast growth factor receptor 1 (FGFR1) were all negative. Cytogenetics showed an abnormal karyotype with 45, XX, -13 (1) [Fig. 2A]/45, XX, -16 (1) [Fig. 2B] /46, XX [Fig. 2C]. Positron-emission tomography with 18F-fluorodeoxyglucose (FDG-PET) was performed. As shown in Fig. 3A, the FDG-PET on Apr 9, 2020 showed positive FDG uptake in multiple enlarged lymph nodes throughout abdominal cavity and in the duodenum, terminal ileum, and colon. Two gastrointestinal specimens on Apr 12, 2020 and May 3, 2020 showed eosinophils invasion (Fig. 4). We also performed laparoscopic lymphadenectomy on Apr 17, 2020 but it didn’t show any diagnostic significance. Ultimately, the diagnosis of idiopathic eosinophilia was made and imatinib combined with prednisone regimen was restarted.
The patient was readmitted 3 months later with obvious abdominal pain and abdominal distension. At the same time, she complained of night sweats and apparent weight loss (5kg). Laboratory data revealed that the leukocyte count was 1.9×109/L and an eosinophil of 1.8%. LDH was 546U/L and total serum IgE was 134.06 KIU/L. EBV-DNA was 8.41×103 IU/ml (upper limit of reference 1×103). Liver function showed Albumin (ALB), 28.9g/L; Alanine aminotransferase (ALT), 254 (upper limit 50) U/L; Asparagus aminotransferase (AST), 122 (upper limit 40) U/L; γ-glutamyl transferase (GGT), 310 (reference upper limit 60) U/L; Alkaline phosphatase (ALP), 156 (upper limit of reference 125) U/Land Direct bilirubin (D-Bil), 11(upper limit 5)µmol/L. The Ultrasound and CT both demonstrated diffuse changes of the liver and multiple enlarged lymph nodes in the retroperitoneum, mesenteric, pelvic cavity and groin. The FDG-PET on July 30, 2020[Fig. 3B] showed multiple enlarged lymph nodes in the body with increased metabolism, enlarged spleen with increased metabolism and segmental thickening of the intestinal wall of the gastric antrum, duodenum, colon and rectum with increased FDG metabolism. Compared with previous CT images, lymph node and spleen lesions progressed, with newly emerged pathological changes of gastric antrum. Retroperitoneal lymph node puncture guided by ultrasound was performed on Aug 6, 2020. The sample of the retroperitoneal lymph node showed that the neoplastic T cells with intermediate-sized nuclei, copious pale/clear cytoplasm and abundant clear cytoplasm [Fig. 5A]. Immunohistochemistry showed that the atypical largel lyphoid cells were CD3+[Fig. 5B], CD4+ [Fig. 5C], CD5+, CD8-, ICOS+ [Fig. 5D], Bcl-6+ [Fig. 5E], PD-1+ [Fig. 5F], Bcl-2+, Ki-67+ (70~80%), CD56-, TIA-1-, CD20-, CD79a-, CD10-; immunoblasts CD30+; follicular dendritic cells CD21+ [Fig. 5G] and scattered lymphocytes EBER+ [Fig 5H]. TCR gene rearrangements were positive [Table 1]. The patient was eventually diagnosed as AITL. After diagnosis, whole exome sequencing was conducted on the lymphoma specimens, followed by Digital PCR analysis on all the specimens before diagnosis involving the bone marrow tissues, two gastrointestinal and abdominal lymph node ones. Two mutations were identified, RHOA (c.482C>A; p. Ala161Glu) and TP53 (c.298C>T; p.Q100X). As shown in Fig.6A and Fig.6B, RHOA and TP53 gene mutations were 0.015% [Fig. 6A(a)] and 4.127% [Fig. 6A(b)] in the gastric specimens on Apr 12, 2020[Fig.6B]. They were equally <0.001 [Fig. 6A(c,d)] in the intestinal specimens on Apr 12, 2020 and increased at a frequency of 0.023% [Fig. 6A(e)] and 1.198% [Fig. 6A(f)] on May 3, 2020[Fig.6B]. They were 1.299% [Fig. 5A(g)] and 3.303% [Fig. 6A(h)] in the abdominal lymph node specimens on Apr 17, 2020 [Fig. 6B] and were elevated by 16.00% and 20.60% respectively on Aug 6, 2020 [Fig. 6B]. Unfortunately, due to tissue problems, we were unable to detect these two mutations in the bone marrow regimens and the gastric ones on May 3, 2020.
As for treatment, anti-CD30 monoclonal antibody (Brentuximab vedotin) combined with CHP chemotherapy (cyclophosphamide 750 mg/m2, pegylated liposomal doxorubicin 40mg/m2, and prednisone 100 mg) was given for seven cycles, followed by autologous stem cell transplantation (ASCT). However, relapse occurred two months later. Then, targeted therapy including Chidamide, Selinexor and Decitabine was tried, but all failed. Now she is undergoing CD30-directed Chimeric Antigen Receptor T(CAR-T) cells therapy at another hospital.