Objective: ET and B-LPD are two distinct, clonal hematologic malignancies with their concomitant existence in a single individual being exceedingly rare.
Case report: A 64-year-old male was admitted with cough, weight loss, maculopapular rash and elevated platelet counts. The rash was present on his face and trunk for 20 days and he had non-productive cough for the past two weeks. On examination, he was found to have cervical lymphadenopathy and splenomegaly (5cm below left costal margin). His blood counts were as follows: hemoglobin 10.8g/dl, hematocrit 37.2%, RBC mass 5.34×1012/L, WBC 62.1×109/L, platelets 1169×109/L. LDH was found to be 816IU/L and C-reactive protein was 2.43mg/dl. Peripheral blood film showed anisocytosis, poikilocytosis, elliptical cells, tear-drop cells, nucleated red blood cells, myelocytes and metamyelocytes. Platelets were markedly increased on film. Leucoerythroblastic blood picture was noted. Suspecting a myeloproliferative disorder, additional investigations were sent while the patient was started on hydroxyurea 1gm daily and allopurinol 100mg daily in addition to antibiotics. Bone marrow aspirate depicted increase in lymphoid cells that constituted around 35% of the total nucleated non-erythroid cell population. M:E ratio was 4:1. Bone trephine showed hypercellularity for age with overall cellularity 90 to 95%. Cellular areas exhibited increase in myeloid precursors along with prominent lymphoid cells and abundant megakaryocytes. Pan-T (CD03) and Pan-B (CD20) marker by immunohistochemistry was applied on bone trephine biopsy specimen which was interpreted as increase in B-lymphocytes. Reticulin stain showed grade MF-2 reticulin fibrosis. Overall findings were suggestive of essential thrombocythemia. In view of increased CD20 positive cells, immunophenotyping by flow cytometry was recommended. CD45 positive lymphoid cells population was 31%. This population showed reactivity to Pan-B-markers i.e. CD19 (26%), CD20 (27%), CD22 (26%), CD23 (11%) and cCD79a (30%) along with HLA-DR (12%) and CD45 (35%). Double bright positivity of CD19 and CD5 typical of CLL was absent. This population also showed positivity to lambda light chains restriction (kappa 0%, lambda 13%). Results were consistent with mature-B-lymphoproliferative disorder (B-LPD). JAK2 mutation was detected by PCR while BCR-ABL1 translocation was not detected by fluorescence in situ hybridization (FISH). Since double bright positivity for CD19 and CD5 was absent along with absence of FMC7, a diagnosis of mature-B-lymphoproliferative disorder was made. Cyclin D1 was applied on bone trephine, which was negative, and the infiltration did not reveal a follicular pattern. Ki67 was approximately 30%. A diagnosis of ET progressing to myelofibrosis and B-LPD was made. Patient was discharged in a stable condition and followed up on an outpatient basis. Ruxolitinib at a dose of 5mg twice daily was initiated while hydroxyurea was reduced to 500mg daily and then later to alternate day dosing. A wait and watch approach was adopted for the B-LPD Ruxolitinib was later increased to 10mg twice daily. After a few months, ruxolitinib was switched to 15mg daily with the counts remaining stable. The patient remains stable and asymptomatic two and half years later. The most recent blood counts show hemoglobin at 10.9g/dl, WBC 31.1×109/L, and platelets 445×109/L.
Methodology: Retrospective review of case.
Conclusion: We report a rare case of ET with concomitant B-LPD. The patient is stable on Ruxolitinib and is on wait and watch approach for B-LPD.
