| Abstract|| |
Hepatosplenic T-cell lymphoma (HSTCL) is a rare extranodal T-cell lymphoma that shows preferential sinusoidal infiltration of spleen and liver. It usually shows bright expression of surface CD3 (sCD3) with restriction for γδ-T cell receptors (TCR). We present a case of a 34-year-old male who presented with hepatosplenomegaly and B symptoms. His peripheral blood and bone marrow (BM) was involved by atypical lymphoid cells that were CD2+, CD7+, CD56+, cytoplasmic CD3+, and sCD3− on immunophenotyping by flow cytometry. As sCD3 is a lineage marker for T-cell lymphomas, the loss of sCD3 posed a diagnostic dilemma. However, typical pattern of sinusoidal BM and liver involvement by CD3+ cells and TCR gene rearrangement positivity led to final diagnosis of HSTCL. The differential diagnosis, workup, and clinical course of the case are discussed. To the best of our knowledge, only one case of de novo HSTCL with negative sCD3 has been reported before in the literature.
Keywords: CD3, hepatosplenic, lymphoma
|How to cite this article:|
Chauhan R, Tyagi S, Mirgh S, Mishra P, Seth T, Mahapatra M, Pati H, Saxena R. Expect the unexpected – Loss of surface CD3 on flow cytometry in hepatosplenic T-cell lymphoma: An eye opener. Indian J Pathol Microbiol 2018;61:275-7
|How to cite this URL:|
Chauhan R, Tyagi S, Mirgh S, Mishra P, Seth T, Mahapatra M, Pati H, Saxena R. Expect the unexpected – Loss of surface CD3 on flow cytometry in hepatosplenic T-cell lymphoma: An eye opener. Indian J Pathol Microbiol [serial online] 2018 [cited 2021 Jun 18];61:275-7. Available from: https://www.ijpmonline.org/text.asp?2018/61/2/275/230550
| Introduction|| |
Hepatosplenic T-cell Lymphoma (HSTCL) is a rare extranodal T-cell lymphoma that shows preferential sinusoidal infiltration of spleen and liver with minimal bone marrow (BM) and peripheral blood (PB) involvement. It usually shows bright expression of surface CD3 (sCD3) with γδ-T cell receptors (TCR). Furthermore, CD3 is a lineage-specific marker for T-cell neoplasms. We present a case where loss of sCD3 in HSTCL posed a diagnostic dilemma. To the best of our knowledge, only one case of de novo HSTCL with negative sCD3 has been reported in literature.
| Case Report|| |
A 34-year-old immunocompetent male presented with painless progressive abdominal distension with fatiguability and B symptoms for 3 months. He denied any history of bone pains, any lumps in neck, axilla, or groin. He had similar symptoms previous year when he was diagnosed with pulmonary tuberculosis (TB) and improved with 6 months of anti-TB-treatment. On examination, he was hemodynamically stable without any clinically significant lymphadenopathy. He was pale, had massive hepatosplenomegaly (liver-12 cm below right costal margin, spleen-28 cm below left costal margin) with evidence of massive left-sided pleural effusion.
His PB counts were hemoglobin - 8.5 g/dL, total leukocyte count - 2350/μl, and platelet count - 1 lakh/μl with the presence of 23% atypical lymphoid cells that were medium sized with high nucleocytoplasmic ratio and coarse chromatin, inconspicuous nucleoli. BM aspirate was cellular with infiltration by these monomorphic lymphoid cells. BM biopsy showed sinusoidal as well as interstitial infiltration of atypical lymphoid cells [Figure 1]a and [Figure 1]b. On PB immunophenotyping (IPT), the gated events in CD45 bright region on CD45/side scatter plot were positive for CD2, CD7, CD56, and cytoplasmic CD3 and negative for sCD3, CD5, CD34, TdT, HLA-DR, gamma-delta, and alpha-beta TCR [Figure 2]. Differential diagnoses of T/NK cell lymphoma/leukemia were considered. Immunohistochemistry (IHC) highlighted CD3+ CD20– intrasinusoidal lymphoma infiltration of BM [Figure 1]c and [Figure 1]d. Further, positivity for CD56 and negativity for immaturity markers (CD34, TdT, and HLA-DR) ruled out the rare possibility of T-acute lymphoblastic leukemia (T-ALL). Liver biopsy also revealed sinusoidal infiltration CD3+ CD20– glycophorin – lymphoid cells. A TCR gene rearrangement showed clonal peak confirming clonal neoplasm of T-cell lineage and ruling out a close differential diagnosis of aggressive NK-cell leukemia (ANKL). Corroborating in toto the clinical findings, typical pattern of liver and BM infiltration with evidence of T-lineage markers on flow cytometry (FCM), a diagnosis of HSTCL was considered. BM cytogenetics turned out to be normal (46XY).
|Figure 1: (a) Bone marrow aspirate (×10) shows infiltration by monomorphic medium-sized lymphoid cells with peripheral blood smear showing atypical lymphoid cells (within inset ×40); (b) bone marrow biopsy shows intrasinusoidal infiltration by these cells (red arrows); (c) immunohistochemistry for CD3 shows CD3 positive lymphoid cell within the sinusoids; (d) immunohistochemistry for CD20 shows these cells are negative|
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|Figure 2: (a) CD45/SSC scatter plot shows 35% CD45 bright events. (b and c) 25% CD45 bright events show CD2+, CD7+ with loss of surface CD3. (d) These events are dual negative for CD4 and CD8 and (e) show positivity for CD56. (f) These CD2, CD7, CD56 positive events are negative for alpha-beta/gamma-delta T-cell receptors|
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X-ray chest-posteroanterior showed massive left pleural effusion with mediastinal shift to the right. Contrast-enhanced computed tomography neck, chest, and abdomen (for staging) showed massive hepatosplenomegaly with splenic infarcts and gross left-sided pleural effusion.
Therapeutic pleural tapping of approximately one-liter fluid revealed an exudative fluid with negative workup for TB and negative cytology.
A final diagnosis of HSTCL Stage-IV with BM involvement (international prognostic index score-3) was rendered.
After obtaining informed consent, he was started on cyclophosphamide, doxorubicin, vincristine, and prednisolone chemotherapy. He tolerated two cycles well and his night sweats decreased. However, his massive organomegaly did not improve significantly. Hence, he was given aggressive chemotherapy, i.e., dexamethasone, high-dose cytarabine, and cisplatin regimen. He developed culture-negative febrile neutropenia on day 7 that improved with intravenous antibiotics and antifungals. He developed bilateral tinnitus since day 10 with evidence of high-frequency sensorineural hearing loss on audiometry examination. Although his audiometry normalized by day 28, in view of persistent tinnitus, he was given ifosfamide, carboplatin, and etoposide chemotherapy. His organomegaly and pleural effusion decreased by more than 50% after the latter two aggressive regimens. Currently, he is planned for an autologous stem-cell transplant.
| Discussion|| |
Although Farcet et al. described the first case of HSTCL in 1990, it is a rare and aggressive malignancy accounting for <5% of all peripheral T/NK-cell lymphomas , and <1% of all NHLs. It is usually seen in middle-aged males (median age of 35 years) with constitutional symptoms, hepatosplenomegaly, and sometimes jaundice. Lymphadenopathy is usually absent. Around 20% cases arise in setting of chronic immune suppression after solid-organ transplant or chemotherapy for leukemia. Our patient was unique as he was immunocompetent.
ANKL is a close differential of HSTCL that occurs in middle-aged adults (median 42 years) with organomegaly, constitutional symptoms, and cytopenias. However, ANKL is an aggressive malignancy with strong association with Epstein–Barr virus.
On IPT, HSTCLs are positive for sCD3, CD2, CD7, and CD56 with loss of CD5 and double negative for CD4 and CD8. NK-cell-associated markers such as CD16, and CD56 are variably expressed present in 60%–70% of all cases. CD57 is usually negative. They also usually express γδ-TCR and only a subset are αβ-TCR positive. Differential diagnoses with similar IPT can be T-ALL where immaturity markers such as CD34 and TdT are positive. Another differential diagnosis is ANKL that shows atypical cells positive for CD16, CD56, and clonal TCR-gene rearrangement negative.
As per literature, two cases of HSTCL showed loss of sCD3 in the event of relapse., Kapur et al. reported a case of de novo sCD3 negative that showed its appearance after chemotherapy. Furthermore, HSTCLs with TCR-silent phenotype are rare. The absence of γδ or αβ-TCR can be explained by loss of sCD3complex on abnormal-T-cells. In our case, another clone for CD3 on FCM was not used as positive expression of CD3 was demonstrated by cytoplasmic CD3 by FCM and IHC. In addition, typical intrasinusoidal pattern of BM infiltration with IHC findings, positive liver biopsy, and clonal TCR-gene rearrangement unveiled the final diagnosis. We hypothesize that explanation for loss of sCD3 could be that neoplasm could have arisen from a stage just prior to complete mature T-cells that might lack complete CD3 complex on surface of T-cells. Rarely, the de novo CD3-negative HSTCL can lose expression for both α and γ-TCRs and become silent phenotype.
Cytogenetic abnormalities such as isochromosome 7q support the diagnosis of HSTCL. However, our patient had normal cytogenetics – 46XY.
Patients with HSTCL have a poor survival rate, despite chemotherapy and BM transplantation therapy. The median survival varies between 0 and 5 years, with rare complete remission. The prognostic impact of sCD3 negativity is unknown because of paucity of data in literature. Our patient tolerated chemotherapy well and is planned for autologous transplant.
| Conclusion|| |
Absent sCD3 expression, leukemic presentation with the presence of NK-cell markers caused the diagnostic dilemma in this case. The take-home message is that hematologists should be cognizant of the entity “de novo sCD3 negative HSTCL with silent TCR phenotype” while dealing with a case of T/NK-cell neoplasm with otherwise typical intrasinusoidal infiltration of BM and hepatic parenchyma.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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Conflicts of interest
There are no conflicts of interest.
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Department of Hematology, Room 202, All India Institute of Medical Sciences, New Delhi - 110 029
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2]