Introduction

Anaplastic large cell lymphoma [ALCL] has undergone numerous definitional revisions from the earliest report by Stein et al. in 1985 which described a subgroup of tumors with large, bizarre, pleomorphic cells associated with prominent sinusoidal invasion and with expression of CD30 [1]. The current definition has evolved to be defined as a mature T cell neoplasm with uniform CD30 expression, hallmark cells, and typically a histologically cohesive growth pattern. Current World Health Organization classification further defines ALCL with ALK-negative and ALK-positive as established variants, the latter characterized by chromosomal rearrangements involving the ALK gene on 2p23. ALK [ +] ALCL represents approximately one-half of ALCL cases and is typically attributed to have superior 5-year overall survival rates of > 70%, when compared to ALCL ALK [ −] 5-year overall survival rates of < 50% [2,3,4,5,6,7,8,9]. Using these criteria, ALCL still represents a group of diseases which are heterogeneous with regard to histology, phenotype, cytogenetics, and clinical course [2, 10,11,12]. Most cases are single-positive CD4 or less often CD8 + T cells or double negative, but only isolated reports for positivity for both antigens [13,14,15]. Here, we report a rare case of ALCL, ALK-negative arising in a military veteran with documented Agent Orange exposure expressing double-positive CD4 + CD8 + and review the literature of this rare phenotype.

Clinical history and results

A 74-year-old male military veteran with past medical history significant for renal cell carcinoma requiring a left nephrectomy and with transporting and loading Agent Orange during military deployment in the Vietnam War presented with a left neck palpable nodule associated with swelling. Computed tomography [CT] revealed isolated bulky bilateral cervical lymphadenopathy. A positron emission tomography [PET-CT] revealed the abnormal FDG uptake of numerous bilateral cervical lymph nodes [3.6 cm, max SUV 23.6, with a SUV range of 3.8–5.9] without signs of abdominopelvic or extranodal involvement (Fig. 1).

Fig. 1
figure 1

PET CT scan that demonstrates a FDG avid ill-defined left level 2 cervical lymphadenopathy measuring 3.6 × 3.0 cm, SUV 23.6

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The left neck lymph node biopsy showed an infiltrate of frankly malignant large lymphoid cells with many featuring eccentric horseshoe/kidney shaped nuclei with an eosinophilic region near the nucleus, consistent with hallmark cells (Fig. 2). By immunocytochemistry the atypical lymphocytes expressed CD45, CD30, CD2[subset +], CD5 and DP CD4 + CD8 + , but negative for CD20, PAX-5, CD3, CD138, CD56, ALK-1, EMA, CD7, Granzyme-B, p63, TdT, CD1a and EBER- in-situ hybridization stains. The proliferation index estimated by Ki-67 staining was 70–80%. Fluorescence in situ hybridization [FISH] studies were negative for rearrangements involving ALK, TP63, and DUPS22 [IRF4] gene regions. A staging bone marrow biopsy showed normocellular bone marrow, with trilineage hematopoietic maturation, and no lymphoid aggregates or atypical lymphoid cells. He was diagnosed anaplastic large cell lymphoma, ALK-negative and subsequently started on 6-cycles of chemotherapy which included cyclophosphamide, doxorubicin, and prednisone, as well as brentuximab vedotin (BV-CHP), as the lymphoma expressed CD30. T cell receptor gene rearrangement could not be performed due to consumption of the material.

Fig. 2
figure 2

a Hematoxylin and eosin stained sections from left neck lymph node with complete architectural effacement and replacement by frankly malignant cells, some of which are hallmark cells with eccentrically placed horseshoe/kidney shaped nuclei with an eosinophilic region near the nucleus [inset] [magnification × 200]. b The neoplastic cells are positive for CD30 stain. c Negative Alk-1 staining is seen [magnification b, c: × 400]. d Positive CD4 expression by the neoplastic cells is seen [magnification × 400]. e The neoplastic cells also express CD8. [magnification × 400]

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Discussion

Here we have reported a rare case of ALCL ALK-negative with immunophenotypic co-expression of both CD4 and CD8 in a military veteran with Agent Orange exposure. The incidence of DP CD4 + CD8 + T cells has been described in other lymphoproliferative diseases, particularly with T cell prolymphocytic leukemia [T-PLL] which can be seen in approximately 25% of cases [16, 17]. Other post-thymic T cell malignancies rarely coexpress these antigens [2], but some reports in the literature have shown this has potential to occur at varying low frequencies; adult T cell leukemia/lymphoma [18], angioimmunoblastic T cell lymphoma [14], peripheral T cell lymphoma, not otherwise specified [14]. In the context of ALCL, there is evidence that expression of either CD4 or CD8 differ biologically and are associated with unique clinical/pathologic differences. It has been reported that ALK-positive ALCL CD8-positive cases show frequent non-classical histology including small-cell/lymphohistiocytic morphology, higher relapse rate and more often requiring stem cell transplant. However, CD8 expression does not appear to impact patient overall survival or progression-free survival regardless of ALK-status [19]. The incidence of DP CD4 + CD8 + ALCL appears to be extremely rare, in fact in our literature review we were only able to identify eight cases [20,21,22]. One study, focusing exclusively on ALCL, highlights five DP CD4 + CD8 + cases with a tendency toward small cell/lymphohistiocytic morphology [4/5 cases], but individual clinical/pathologic features are not delineated further [22]. The remaining studies are summarized in Table 1, and interestingly small cell morphology also appears to be common in these cases as well [2/4 cases].

Table 1 A summary of reported DP CD4 + CD8 + anaplastic large cell lymphoma cases reported in the literature and the present case
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The biology of CD4 + CD8 + T cells is well described as a developmental stage within the cortical thymus, where they mature from early T cell precursors that express TdT and exhibit double negativity for both CD4 and CD8. Furthermore, the biology of these maturing T cells includes, well organized T cell antigen receptor (TCR) gene somatic rearrangements to generate a broad repertoire of TCR structures. Negative and positive selection at this stage of development results in the deletion of autoreactive thymocytes and ensures that class I and class II major histocompatibility complex (MHC) reactivity is correlated with CD8 and CD4 lineage specification [23]. To eliminate cells expressing TCRs that cannot engage self MHC molecules, DP thymocytes are subjected to strict selection pressures in which cells bearing potentially useful TCR are the only ones signaled to survive and to continue their differentiation into functionally mature T cells. The vast majority of DP thymocytes do not receive TCR survival signals and undergo ‘death by neglect’ because their TCR cannot engage self MHC molecules. This life-or-death TCR-mediated signalling event in DP thymocytes is known as ‘positive selection’ and results in the survival and maturation of cells bearing potentially useful TCRs [24]. Subsequently, these double-positive CD4 + CD8 + T cells upon leaving the thymic cortex express either CD4 or CD8 and can be found in paracortex of lymph nodes, and in the thymic medulla. Also, methylation studies reveal that ALK ( +) ALCL DNA methylation pattern resembles that of an early thymic progenitor, while ALK ( −) ALCL largely clustered with DP TCR-expressing, as well as pre-TCR T cells [25]. While it would remain unclear why a DP- phenotype in ALCL is so exceedingly rare, this does provide some evidence of a postulated cell of origin. Detection of mature CD4 + CD8 + T cells have been reported in the peripheral blood of healthy people as a small population [1–3%] [26, 27], but can be expanded in various reactive etiologies including autoimmune diseases, viral infections, and other various chronic inflammatory conditions and lymphomas including nodular lymphocyte-predominant Hodgkin lymphoma [28,29,30,31,32]. The functional aspects of DP T cells are poorly understood with conflicting evidence for both a cytotoxic and/or regulatory role [25]. It is unclear, but conceivable that a lymphomatous process could derive from this biologically distinct DP T cell subset, although certainly upregulation by various mechanisms, including the neoplastic process would remain possibilities.

It is notable that the patient had been involved with transporting and loading Agent Orange during military deployment in the Vietnam War. Agent Orange was a mixture of two herbicides 2,4-dichlorophenoxyacetic acid [2,4-D], 2,4,5-trichlorophenoxyacetic acid [2,4,5-T], that was contaminated by TCDD [2,3,7,8-tetrachlorodibenzine-p-dioxin] during production and used by the U.S. military during the Vietnam War in the period 1962 to 1971.

While the mechanism is not completely understood in vitro and laboratory animal models have highlighted the importance of species-specific aryl hydrocarbon receptor, which has potential to alter gene expression. Veterans and Agent Orange (VAO) committee, which was established to review the health effects of exposure to herbicides in Vietnam Veterans, currently concludes that there is sufficient evidence to support an association between prior herbicide exposure and non-Hodgkin lymphoma (including chronic lymphocytic leukemia, hairy cell leukemia and other chronic B cell leukemias), Hodgkin lymphoma and monoclonal gammopathy of undetermined significance [33]. Of note, Lorio and colleagues report a case of cutaneous ALK( −) CD4( +)CD8( −) ALCL arising in a 68-year old man, that was accepted by the US Department of Veterans Affairs as an Agent Orange‐related lymphoproliferative disorder [34]. Additional cancers that are associated with Agent Orange exposure include soft tissue sarcoma as well as numerous with limited or only suggestive evidence (prostate, bladder, lung, laryngeal cancer etc.) [35, 36].

Of note, definitive determination of what constitutes a significant exposure to herbicides and TCDD is practically difficult given lack of reliable laboratory metrics, nor consistent data or robust tools to accurately track proximity and duration of an exposure [35].

Conclusion

In summary, we report herein a rare case of ALCL ALK [ −] with concurrent expression of both CD4 and CD8 arising in a military veteran with documented Agent Orange exposure. We emphasize that further accumulation of similar cases is warranted to clarify and elucidate any further unique clinicopathological findings.