Clinical genomic profiling of novel grey zone lymphoma paired lesions with sequential central nervous system involvement in two adolescent patients

Grey zone lymphoma (GZL), defined as B-cell lymphoma, unclassifiable, with features intermediate between large B-cell lymphoma (LBCL) and classic Hodgkin lymphoma (cHL) (BCL-U-IND) is a rare diagnostic entity.^1-3 Synchronous GZL, LBCL and cHL occurring simultaneously in the same patient, and sequential GZL, LBCL preceding or following a diagnosis of cHL, are even less common.⁴ We identified two adolescent patients, a 17 year-old male (17M, case #1) and 16 year-old female (16F, case #2), who were diagnosed with stage IV nodular sclerosis cHL (NS-cHL) with primary mediastinal location and subsequent central nervous system (CNS) LBCL. Copy-number alterations were assessed using Affymetrix OncoScan^® microarray analysis, and targeted next-generation sequencing (NGS) using a capture-based 152 gene custom-designed hematologic malignancy panel was performed on paired cHL and CNS LBCL tumors to assess for genomic alterations as previously described.⁵ These studies were performed under institutional-approved study protocols. We present the clinicopathologic and genomic features of the paired lesions in this previously unreported presentation of pediatric sequential GZL.

Table 1.Clinicopathological summary of sequential grey zone lymphomas.

Table 2.Tissue-based cancer microarray and next-generation sequencing analysis of sequential grey zone lymphomas.

Figure 1.Representative pathologic findings of sequential grey zone lymphomas (Case #1). Initial cervical lymph node biopsy shows classic Hodgkin lymphoma (upper panel, A to C). (A) Characteristic Hodgkin and Reed–Sternberg (HRS) cells are present in a polymorphous inflammatory background (hematoxylin and eosin stain[H&E]); the HRS cells are negative for EBER (inset A). (B) The neoplastic HRS cells are positive for CD30 (red, membranous) and weekly positive for PAX-5 (brown, nuclear). (C) They are negative for CD20. (D to F) Lesional brain biopsy shows sequential central nevous system large B-cell lymphoma (lower panel). (D) Diffuse sheets of large lymphoma cells shows centrally located prominent nucleoli (H&E); they are negative for EBER (inset D). (E) The lymphoma cells are diffusely positive for CD30 (red, membranous) with strong nuclear PAX-5 (brown) expression, (F) and express strong and homogeneous CD20.

Case #1, 17M. A 17 year-old male presented with large mediastinal and supraclavicular masses with disseminated spleen, liver, and bone lesions. Left cervical lymph node sampling revealed the classic histology and immunophenotype of NS-cHL (Figure 1A to C, Table 1). A concomitant outside bone marrow sample performed approximately 3 weeks prior revealed LBCL with sizable clusters of large lymphoma cells, consistent with a diagnosis of synchronous GZL. Staging bone marrow was negative for involvement by lymphoma. Complete remission was achieved after initial treatment with ABVE-PC chemotherapy regimen. Six months, after initial diagnosis (2 months post-therapy), several supra- and infra-tentorial brain lesions and extensive leptomeningeal disease appeared. A biopsy of a CNS lesion revealed diffuse sheets of large lymphoma cells having open chromatin, prominent centrally located nucleoli, and a moderate amount of clear to eosinophilic cytoplasm. The lymphoma cells showed diffuse and strong expression for CD45, CD20, PAX-5, CD30, and expression of CD79a, and were negative for CD15, EBER, and ALK (Figure 1D to F, Table 1). A diagnosis of BCL-U-IND consistent with sequential GZL was rendered. He was treated according to POG9917 Arm A as a bridge to bone marrow transplant with a mismatched unrelated donor and received total body irradiation (450 cGy). He was alive at 81.7 months follow-up.

Case #2, 16F. A 16 year-old female presented with a large mediastinal mass with cervical lymphadenopathy and multiple bilateral renal and pulmonary nodules. NScHL was diagnosed from cervical lymph node biopsy; staging bone marrow was negative. She achieved complete remission after ABVE-PC and radiotherapy to the mediastinal mass and other slow-responding areas of disease. Seven months after initial diagnosis (2 months posttherapy), a solitary right temporal lesion was identified. A biopsy revealed essentially similar morphologic and immunophenotypic findings to the CNS lesion of case #1 (Table 1), and a diagnosis of BCL-U-IND, consistent with sequential GZL was rendered. She was treated with ANHL1131 Group C1 and surgical excision and was alive at 13.5 months follow-up.

Molecular findings. The microarray and NGS results are summarized in Table 2. In both NS-cHL, near-diploid male or female genomes and no variants of established or potential clinical significance (Tier I/II, Table 2) were detected consistent with “negative” genomic profiles reported in bulk cHL lesions without Reed-Sternberg cell enrichment.^6,7 In case #2, a shared 3.0 MB region of copyneutral loss of heterozygosity (LOH) in chromosome 1p36.11-p35.3 was observed that was most likely germline in origin. Both CNS LBCL harbored complex cytogenomic arrays including 2p16.1 and 9p24.1 gains (detected in both cases, Table 2, denoted by *) and 16p13.3 copy-number abnormalities (case #2 only). LOH of chromosome 6p and gain of chromosome 12p were also observed in both CNS LBCL (Table 2, denoted by *). NGS revealed shared NS-cHL/CNS LBCL variants of uncertain significance (VUS, Tier III) in CREBBP p.T974N (case #1) and RELN p.N352S and KMT2D p.E4694Q (case #2). The sequential CNS LBCL in case #1 harbored additional Tier III variants including APC p.G53R, FAT1 p.L761W, and NOTCH3 p.R2109Q. The sequential CNS LBCL in case #2 harbored pathogenic (Tier I/II) TP53 p.C238R and FBXW7 p.R465H missense variants.

In this report, we detailed the clinicopathologic and molecular features of two adolescent patients with sequential GZL involving the CNS. Notably, this is the first report describing CNS involvement as a manifestation of sequential GZL, a finding which expands the clinicopathologic spectrum of this rare pediatric disease. Consistent with previous reports, both patients presented with mediastinal NS-cHL and advanced extranodal disease with similar histopathologic and immunophenotypic findings, and developed GZL in a similar chronologic fashion.^4,8 The sequential CNS lesions showed differing morphologic and immunohistochemical profiles with strong and diffuse expression of several B-cell markers and CD30, the latter arguing against an extramediastinal primary mediastinal B-cell lymphoma (PMBCL) diagnosis, and the NS-cHL diagnosis preceded the diagnosis of LBCL temporally establishing the sequential GZL diagnosis. Additionally, the findings of synchronous GZL with subsequent development of sequential GZL in the first patient is also exceptional. Furthermore, unlike previous reports, an early evolution (e.g., second lymphoma diagnosis within 1 year) may not necessarily portend a poor clinical outcome⁴ given the favorable clinical responses in our two patients and a relatively long term follow-up in the first.

Recent molecular characterization of GZL supports the classification of two distinct subtypes of GZL: a "thymic" subtype that occurs in the anterior mediastinum and resembles Epstein-Barr virus (EBV)-negative cHL and PMBCL, and a “non-thymic” subtype which occurs outside the thymus and harbors TP53 mutations in a subset of cases.^9,10 In our two patients, the CNS location and mutations in TP53 (case #2) and other associated genes (e.g., CREBBP, RELN, and KMT2D) support a “nonthymic” GZL classification. The presence of complex genomic profiles is also consistent with dysregulated TP53 signaling, and both CNS LBCL harbored complex cytogenomic arrays with copy number abnormalities previously reported in GZL^11-13 and frequently reported in cHL and PMBCL.^14,15 We acknowledge that a thorough investigation of enriched Reed-Sternberg cells from the cHL lesions and specific subsets of lesional cells may yield valuable molecular insights but this was beyond the scope of the current study.

In summary, we present the first report of sequential GZL with CNS involvement in two adolescent patients, and the first clinical genomic profiling of such paired lesions. These lesions showed chromosome aberrations identified in GZLs and NGS mutations associated with non-thymic GZL. These findings expand the clinicopathologic and genomic spectrum of this rare pediatric disease.

Footnotes

• Received April 8, 2021
• Accepted June 16, 2021

Correspondence

^#KEF and CVC contributed equally as co-senior authors

CHOLADDA V. CURRY - ccurry@bcm.edu

Disclosures: no conflicts of interest to disclose.

Contributions: CYB researched the literature, wrote the manuscript, and constructed the tables/figures; ANM, JEA, AMA, and HLW assisted with reviewing medical and pathological records of patients involved, as well as manuscript editing; KEF and CVC conceived the study, interpreted the data, provided feedback and supervision. All authors contributed to patient care, manuscript editing, and evaluation.