Introduction

Hairy cell leukaemia (HCL) is an indolent B-cell lymphoproliferative neoplasm characterized by circulating mononuclear cells with hairy projections and clinically manifested by pancytopenia and splenomegaly [1]. 2-Chlorodeoxyadenosine (2-CdA), a purine analogue appeared to be highly effective in the treatment of HCL with a paucity of toxicities [2]. The common side effects of 2-CdA include prolonged immunosuppression and reversible myelosuppression [3]. Herein, we report a male patient with A pandemic 2009-H1N1-associated pneumonia who fully recovered after oseltamivir despite prominent marrow infiltration with hairy cells. The subsequent treatment with 2-CdA resulted in irreversible marrow aplasia followed by fatal Aspergillus infection. To the best of our knowledge, this is the first report of irreversible marrow aplasia after 2-CdA.

Case presentation

A 49-year-old man was referred to Haematologic Clinic in March 2010 due to prolonged severe pancytopenia after 2-CdA. His history started in November 2009 with progressive weakness, bone pain and fever up to 40°C. He was hospitalized in Internal Ward of Provincial Hospital. On admission, he looked severely ill. The physical examination showed tachycardia and tachypnoe. His respiration was shallow and laboured, percussion note was dull at the base of the both lungs and on auscultation the breath sounds were diminished. His spleen was significantly increased: 10 cm below lower costal margin. The rest of physical examination was normal. Blood tests disclosed moderate pancytopenia: white blood cell (WBC) count 2.9 × 109/l with 26% of neutrophils, 60% of lymphocytes and 14% of monocytes. Haemoglobin (Hgb) concentration was 10 g/dl, and platelet (Plt) count was 54 × 109/l. The peripheral blood film showed numerous typical hairy cells. Laboratory tests were normal except of significantly increased serum C-reactive protein (CRP) level: 289 mg/l (normal range 0–5 mg/l). Imaging studies including chest X-ray and CT scans revealed bilateral pneumonia. An abdominal ultrasound confirmed splenomegaly (21 × 11 cm). The presence of A 2009-H1N1 virus was confirmed by polymerase chain reaction (PCR) from a throat swab, whereas CMV and EBV PCR tests were negative. Repeated blood cultures remained negative. Oseltamivir (Tamiflu, Roche) was administered at 75 mg twice a day for next 2 weeks. Ciprofloxacin and amoxycyllin were also given. Complete disappearance of previously described pulmonary abnormalities was achieved. Trephine biopsy performed after pneumonia resolution demonstrated hypercellularity and 90% marrow infiltration with small lymphoid cells exhibiting CD20+CD25+DBA44+ immunophenotype. Normal haematopoietic cells were greatly reduced and reticulin was increased. The diagnosis of HCL was eventually established. The repeated haematology performed before 2-CdA initiation in February 2010 was as follows: WBC: 4.9 × 109/l with 63% of lymphocytes, 24% of neutrophils and 13% of monocytes. Hgb concentration was 12.1 g/dl, and Plt count was 76 × 109/l. 2-CdA at dose of 12 mg daily (0.12 mg/kg in 2-hour intravenous infusion) for 5 consecutive days was administered with good tolerance at Regional Oncology Unit. Granulocyte-colony-stimulating factor (G-CSF) at dose of 0.3 mg subcutaneous for 5 days was given as neutropenia prophylaxis. Three weeks later, patient was admitted to our Clinic due to severe pancytopenia (WBC-0.1 × 109/l, Hgb-7.4 g/dl and Plt- 10 × 109/l). He developed fever >39°C with productive cough. Chest X-ray and CT scans were suggestive of fungal infection. There was no splenomegaly in CT abdomen scan. Sputum culture demonstrated the presence of aspergillus species; in addition, galactomann test appeared to be positive. Bacterial and viral infections were excluded. Trephine biopsy was leukaemia free, with significantly diminished marrow cellularity (1%), and its picture was consistent with marrow aplasia. Treatment with G-CSF, vitamins B6 and B12, folic acid, steroids and anabolics did not reverse marrow dysfunction. Patient died among symptoms of multi-organ failure despite anti-fungal therapy while still deeply pancytopenic more than 2 months after 2-CdA initiation. Autopsy studied confirmed marrow aplasia and systemic aspergillosis.

Discussion

The treatment of HCL with 2-CdA has dramatically improved the clinical course and prognosis of this rare disorder [4]. However, it should be mentioned that 2-CdA may have an adverse impact on the immune system and results in decrease of cellular-based immunity for about 12 months after completion of therapy [5]. In a vast majority of patients with HCL, the treatment with purine analogues is well tolerated, whereas some have severe complications resulting from myelo- and immunosuppression. Of note is that the improvement in peripheral counts may require weeks or even months; however, an irreversible marrow aplasia was not documented so far [6]. However, there have been single reports of marrow failure after 2-CdA. Myelodysplastic features may occur after therapy with purine analogue, but actually some of the presented patients had been previously treated with alkylating agents [7, 8]. It is likely that a small subset of patients with HCL may develop therapy-related myelodysplastic syndrome (MDS) within 10 months after first infusion of purine analogue, but this was reported for 2-deoxycoformycin (DCF) [9]. The development of pure red cell aplasia (PRCA) after 2-CdA is also not well understood. Patients previously treated with 2-CdA showed 1% rate of PRCA, and the frequency seemed to be higher in the patients treated with combined modalities. Only two patients developed PRCA after 2-CdA alone [10]. Some large studies showing long-term follow-up data on the efficacy and safety of 2-CdA in HCL were published recently, but no prolonged marrow aplasia was reported. A scant attention has also been paid to marrow histology after therapy [11–13]. In a Jehn study [4], all patients showed a marked myelosuppression, but only few of them required G-CSF due to prolonged neutropenia and a median time to neutrophils recovery was merely 11 days. It is noteworthy that bone marrow aspiration and core biopsy were performed simultaneously before and after therapy with 2-CdA, but there were lacking data on marrow cellularity. Moreover, in a large immunomorphologic study of bone marrow biopsies obtained after therapy with 2-CdA, the cellularity was not provided [14]. Regarding this issue, Gillis et al. [15] presented an interesting report. They reviewed 94 marrow biopsies in 31 patients with HCL, both before and after treatment with 2-CdA. Hypoplastic and aplastic foci were found in only 3 (13%) of pre-therapy biopsies whereas in 47 (66%) after at least one course with 2-CdA. It should be noted that the majority of biopsies had no evidences of HCL and peripheral blood results remained normal. Based on this study, we can formulate two conclusions: (1) bone marrow includes areas with normal haematopoiesis and with hypoplastic foci and (2) careful follow-up is needed to assess the risk of aplasia development. As these hypoplastic foci were present more frequently in biopsies after 2-CdA, we can speculate that they are therapy related. Of note is that the similar number of hypocellular foci was seen not only early after 2-CdA treatment, but also later than 1 year after therapy. The detailed analysis of biopsy obtained prior therapy in our patient did not reveal any hypoplastic foci, whereas the presence of aplastic marrow was confirmed twice from two different posterior iliac crests after therapy and once during autopsy. The question is whether A 2009-H1N1 virus was somehow involved in marrow aplasia after 2-CdA? We can only speculate that prior viral A 2009-H1N1 infection might be in part responsible for such dramatic disease course in presented patient, but up-to-date there are no reported cases of marrow hypoplasia/aplasia or even pancytopenia caused by this virus. Moreover, information regarding evolution of influenza A 2009-H1N1 in immunocompromised patients is scarce. In a recently published report, ten patients with acute lymphoblastic leukaemia developing pandemic influenza A 2009-H1N1 while on chemotherapy. Most patients had mild disease and no viral-associated marrow failure was observed [16]. It should be also mentioned that this virus had no harmful effect on bone marrow function in two patients early after allogeneic stem cell transplantation [17]. Regarding our case, we observed a moderate improvement in peripheral blood results after resolution of viral infection, and that may imply its detrimental effect on marrow function. However, it is noteworthy that complete recovery of A 2009-H1N1-associated pneumonia was achieved despite the presence of immunocompromised disease. Our case raises the question of first-line treatment for HCL preceding by severe viral infection. It was proved that 2-CdA administered daily or weekly has similar toxicity profile [12], but interferon alpha seems to have better safety profile [18]. In retrospect, we would recommend treatment delay in this particular case, the more the blood results were stable. On the other hand, patient had thrombocytopenia, marked splenomegaly and diffuse marrow infiltration with hairy cells. There were also no symptoms of active pulmonary infection.

In conclusion, the definite role of A 2009-H1N1 virus on marrow function remained unexplained. It is important to be aware of the fact that irreversible marrow aplasia may occur after 2-CdA, but its patomechanism is not well understood. Careful follow-up of patients treated with purine analogues is therefore strongly recommended.