Adult T-Cell Leukemia-Lymphoma Presenting Concurrently with Myelopathy

Abstract

Human T-cell leukemia virus type 1 (HTLV-1) is an oncogenic retrovirus. Of the approximate ten to twenty million people currently infected worldwide, 4-9% of infected individuals develop adult T-cell leukemia/lymphoma (ATLL) or HTLV-associated myelopathy/tropical spastic paresis (HAM/TSP) in their lifetime. The current report is based on a patient who presented concurrently with CD30+ lymphoma subtype ATLL and HAM/TSP. The patient's ATLL responded to brentuximab-vedotin-based chemotherapy; however, HAM/TSP did not improve. The patient's peripheral blood mononuclear cells were cultured and injected into immunodeficient mice, and the mice developed massive organ involvement and chronic lymphocytic leukemia-subtype ATLL. This case study is novel in the findings of concurrent development of ATLL and HAM/TSP, the response to brentuximab-vedotin chemotherapy, and the use HTLV-1 helix basic zipper protein-targeted probe for RNAscope for diagnosis.

Keywords: Adult T-cell leukemia/lymphoma; Brentuximab-vedotin; HTLV-associated myelopathy/tropical spastic paresis.

Fig. 1

PET scans before and after treatment. a PET/CT performed prior to treatment showed a large infiltrative mediastinal mass which was encasing the trachea and bronchi, with obliteration of the lumen of the right upper and middle lobe bronchi. The mass extended along the right paratracheal region. There was a conglomerate of right supraclavicular lymph nodes which demonstrated markedly increased metabolic activity. The mass extended to the left aspect of the trachea and into the aortopulmonary window as well as the subcarinal region. The maximum SUV was 13.8. This uptake was markedly greater than liver, consistent with a 5PS = 5. Resultant airspace opacities were seen distal to the areas of bronchial compression, which did not demonstrate increased FDG uptake. This likely represented postobstructive pneumonia. Right middle lobe collapse was seen. The mass was seen on the prior contrast-enhanced CT to be attenuating and compressing the right pulmonary arterial tree. An enlarged mesenteric lymph node was seen which measured 1.9 cm, with a maximum SUV of 7.3. An additional smaller hypermetabolic 1-cm mesenteric lymph node was seen inferiorly. Additional CT findings included diffuse body wall edema, calcifications in the left hemithyroid, a moderate right pleural effusion, and an evolving left lower lobe infarct were noted, without substantially increased metabolic activity. b PET scan after completion of therapy showed a new focus of increased activity along the left frontoparietal cerebrum, as well as within the central cerebellum along the posterior aspect of the fourth ventricle. There was near-resolution of extensive consolidation and pleural effusion of the right lung, with a few scattered areas of residual right upper lobe consolidation. Extensive cavitary change in the anterior segment right upper lobe corresponded to healed areas of prior necrotizing pneumonia. Mediastinal soft tissue centered in the subcranal region had resolved. There was no focus of residual increased activity, other than linear prevertebral metabolic activity which corresponded to the esophagus. New mildly increased activity of both L2 and to lesser extent within the tonsils, as well as because of the anterior lower oral cavity were likely inflammatory. Mildly increased activity at the gastroesophageal junction suggested focal esophagitis. There was new marked increased activity corresponding to areas of irregular thickening of the bladder base, suggesting severe cystitis. A 4-cm photopenic defect in the left bladder had no corresponding finding on a prior CT, suggesting new development of an intraluminal mass, which was most consistent with thrombus. Focal increased activity at the left sacral ulcer site was seen. A brain MRI obtained at that time showed scattered T2/FLAIR hyperintensities, compatible with chronic small vessel disease. No areas of abnormal contrast enhancement were seen.

Fig. 2

Pathological findings of the anterior mediastinal mass. Sections of the right paratracheal 4R lymph node obtained at bronchoscopy showed (a) partial effacement of nodal architecture by a diffuse infiltrate consisting of (b) medium to large sized atypical cells with irregular nuclear contours, high nuclear to cytoplasmic ratio, and occasional prominent nucleoli. The neoplastic cells showed focal sinusoidal infiltration. The background showed increased apoptosis, mitotic figures, and foci of necrosis. Flow cytometry showed 27% of total events within the designated lymphocyte gate, 95% of which were CD3 positive T cells which showed a CD4-to-CD8 ratio of more than 10:1 with no significant coexpression of CD4 and CD8 among T cells. The abnormal T cells were positive for cytoplasmic CD3, CD30 (64%), and CD45 (bright), negative for TdT, and showed retained expression of CD2, and near complete loss of expression of CD5 and CD7. CD1 and CD10 were negative. Immunostains were performed to characterize staining of cells in tissue context. The neoplastic infiltrate was diffusely positive for (c) CD3 and (d) CD4 and showed coexpression of CD2 and (e) CD30 with significant loss of CD5 and CD7 expression. Immunostains for ALK-1, TdT, CD1a, and ISH-EBER were negative. CD20 highlighted small nonneoplastic B cells mainly with a follicular distribution. f RNAscope was positive (arrows) with an HBZ probe, (g) negative with non-expressed bacterial dihydrodipicolinate reductase B probe, and (h) positive with a constitutively expressed human peptidyl-prolyl cis-trans isomerase B probe. Formalin-fixed, paraffin-embedded tissues were used for in situ hybridization using RNAscope (ADC Biotechnology), according to the manufacturer's protocol. In brief, 4–5-μm thick sections were prepared from patient samples and baked at 60°C for 1 h followed by deparffinization and pretreatments. Hybridization was performed at 40°C for 2 h using HybeZ hybridization oven using an HBZ specific probe (targeting nucleotides 173–1,363 in the HBZ RNA) or a positive (Hs-PIPB, targeting human housekeeping gene) or negative (DapB) control probe. Amplification and detection of signals were followed accordingly and the sections were counter stained using hematoxylin. Images were taken using a Nanozoomer digital slide scanner (Hamamatsu Photonics).

Fig. 3

PDX model of ATLL with patient peripheral blood lymphocytes. Short-term cultured PBMCs from the patient were injected into two NSG-Kit mice. After 8 and 9 weeks, respectively, the mice lost weight and were sacrificed and necropsy was performed. a–h Blood smears exhibited abnormal large and small cells, many of which had highly lobulated nuclei. (i–k) Mice exhibited massive splenomegaly, and FACS analysis of splenocytes showed a mixture of single- and double-positive CD4+ and CD8+ lymphocytes. PBMCs from the patient were collected at baseline and grown for 14 days in RPMI-1640 medium supplemented with 10% fetal calf serum, 4 mM glutamine, 50 μg/mL penicillin and streptomycin, 50 units/mL interleukin 2, and 25 μL/mL of human CD3/CD28 T-cell activator reagent (ImmunoCult; Stem Cell Technologies, Cambridge, MA, USA). FACS analysis of cultured cells confirmed expansion of T cells with approximately equal numbers of CD4 and CD8 cells by day 5. After 14 days in culture, 5 million cultured cells from the patient were injected intraperitoneal into each of two NSG-Kit mice (Jackson Labs). Mice were sacrificed after 8 and 9 weeks, respectively, when weight loss and dehydration was first noted, and necropsy performed. All animal studies were performed in accordance with research protocols approved by the Institutional Animal Care and Use Committee (IACUC; Animal Welfare Assurance #A-3381-01) at Washington University. (l) Clonal abundance of unique integration sites within tumor of one of the mice is shown. DNA obtained from fresh PBMCs obtained before and after therapy as well as splenocytes from two PDX mice were submitted to the McDonnell Genome Institute at Washington University for Illumina sequencing after probe capture to detect somatic variants that recurrently emerge in ATLL. At 2,000–5,000 coverage, this method had the power to detect somatic variants present in ATLL clones if the clone represents more than 0.1–0.25% of the sample.