Report of a male patient with brain metastases from breast cancer

As in female patients, the clinical course in male patients with breast cancer is determined mainly by tumor stage. The literature contains very limited data on either the occurrence or the treatment of CNS metastases. This paper presents the case report of a 69-year-old man with multiple brain metastases 7 years after a diagnosis of lymph-node positive breast cancer, which had earlier already spread to the bones and liver. Whole-brain irradiation with a total dose of 30Gy resulted in palliation of symptoms. Nevertheless, survival was very short (7 weeks from diagnosis). Patients with metastatic breast cancer are at risk for the development of brain metastases. When performance status is poor the survival of patients with brain metastases is very limited. Treatment recommendations are the same as those for female patients with brain metastases from breast cancer.

Phosphorylation of tyrosine 393 in the kinase domain of Bcr-Abl influences the sensitivity towards imatinib in vivo

The Bcr-Abl fusion protein arising through the t(9;22)(q34;q11) reciprocal translocation is the causative agent in chronic myeloid leukemia and a subset of acute lymphocytic leukemia. Imatinib mesylate is a specific inhibitor of the Bcr-Abl kinase and has shown promising results in clinical studies. The structural relation between the Bcr-Abl oncogene and the tyrosine kinase inhibitor imatinib has recently been elucidated by an elegant crystal structure analysis, emphasizing the importance of dephosphorylated tyrosine 393 (Tyr393) in Bcr-Abl for access of the inhibitor to the kinase domain. By mutating this tyrosine to phenylalanine and thereby mimicking a constitutively dephosphorylated state, we now show that Ba/F3 cells transformed by this mutant demonstrate an increased sensitivity towards imatinib in vivo. This effect is not due to an impaired kinase activity of Bcr-Abl Y393F, since a synthetic substrate is phosphorylated with similar kinetics. Treatment of Ba/F3 cells transfected with Bcr-Abl wild type with a phosphatase inhibitor diminished the effect of imatinib, but did not influence the growth of Ba/F3 cells transfected with Bcr-AblY393F. The results support the findings of the crystal structure and indicate that Tyr393 indeed plays a significant role for the sensitivity of Bcr-Abl towards imatinib in vivo. These data implicate the regulation of Tyr393 phosphorylation as a potential mechanism of imatinib resistance.

Phase II trial of irinotecan plus docetaxel in cisplatin-pretreated relapsed or refractory oesophageal cancer

This phase II trial assessed the toxicity and efficacy of irinotecan plus docetaxel in cisplatin-pretreated oesophageal cancer. Irinotecan 160 mg m(-2) plus docetaxel 65 mg m(-2) once every 3 weeks led to severe myelosuppression in four patients, all of whom experienced neutropenic fever. After amendment of this regimen, 24 patients (male/female=18/6; median age=58.5 years; ECOG performance status 0/1/2=9/11/4) with advanced oesophageal cancer (adenocarcinoma/epidermoid carcinoma=13/11) received irinotecan 55 mg m(-2) plus docetaxel 25 mg m(-2) on days 1, 8 and 15 of a 28-day cycle. Serious adverse events occurred in five patients, one with lethal outcome (pneumonia). Haematological toxicity >or=3 degrees was rare, whereas nonhaematological toxicity >or=3 degrees was noted in nine out of 24 patients (asthenia in five patients, diarrhoea in three patients, nausea/emesis in two patients, constipation in one patient). Median survival time was 26 (range 2-70) weeks. Response rate, assessed according to the WHO criteria, was 12.5% (95% CI 2.7-32.4%); rate of disease stabilisation (partial remission and stable disease) was 33.3% (95% CI 15.6-55.3%) with a median duration of 18.5 (range 16-51) weeks. Although the nonhaematological toxicity proved to be considerable, weekly irinotecan plus docetaxel is feasible and shows some activity in extensively pretreated patients with oesophageal cancer.

Resistance of Philadelphia-chromosome positive leukemia towards the kinase inhibitor imatinib (STI571, Glivec): a targeted oncoprotein strikes back

Cancer research within the last decades elucidated signaling pathways and identified genes and proteins that lead or contribute to malignant transformation of a cell. Discovery of the Bcr-Abl oncoprotein as the molecular abnormality causing chronic myeloid leukemia (CML) paved the way for the development of a targeted anticancer therapy. The substantial activity of imatinib mesylate (STI571, Glivec) in CML and Philadelphia (Ph)-chromosome positive acute lymphoblastic leukemia (Ph+ ALL) changed the therapeutic approach to Ph+ leukemia and rang the bell for a new era of anticancer treatment. However, when the phenomenon of relapse occurred despite continued imatinib treatment, we had to learn the lesson that imatinib can select for a resistant disease clone. If such a clone still depends on Bcr-Abl, it either carries a BCR-ABL point mutation that prevents binding of the drug or expresses the fusion protein at high levels. Alternatively, leukemia cells that harbor secondary genetic alterations resulting in Bcr-Abl-independent proliferation are selected for their growth advantage in the presence of imatinib. Point mutations in the BCR-ABL kinase domain prevent binding of imatinib but still allow binding of ATP, thus retaining Bcr-Abl kinase activity. Mutated BCR-ABL is frequently detected in cases of imatinib-resistant Ph+ leukemia and therefore represents the main challenge for the investigation of alternative strategies to either overcome resistance or to prevent the emergence of a resistant leukemic clone.

Influence of differing radiotherapy strategies on treatment results in diffuse large-cell lymphoma: a review

In the absence of evidence from randomised trials, radiation treatment of diffuse large-cell lymphoma of B-cell type represents an area of controversy with considerable differences in patterns of practice. The present literature survey aims at clarification of the role of radiotherapy in combined modality settings by identification of dose-response relationships, predictive factors for local control, and potential pitfalls in the interpretation of retrospective studies. Radiotherapy might increase local control in initially involved areas and is usually delivered to these sites (involved-field treatment). Combined modality treatment is currently recommended for patients in stage I or II if they are not treated in the context of prospective studies. Whether involved-field consolidation radiotherapy after systemic treatment in patients with bulky, stage III-IV lymphomas should be routinely recommended is presently unclear. Definition of bulky disease is arbitrary and varied between 6 and 10cm, reflecting a considerable difference in the number of clonogenic tumour cells. Several retrospective and one prospective randomised study suggest improved disease-free and overall survival by radiotherapy in advanced stages. The 5-year local control by radiotherapy was 93-98%. Currently, we recommend the following minimum doses for involved-field radiotherapy derived from this literature survey. Lymphomas with initial size <3.5 cm (possibly <6 cm) can be treated with 30 or 30.6Gy when a complete remission (CR) has been achieved by chemotherapy. The next group might be sufficiently controlled by 36Gy, but it remains unclear whether the cut-off should be 6cm or higher. Forty Gy appears to control tumours in the range of 7-10cm. Most likely, 45Gy does not have to be exceeded for larger lesions. Data on those with less than CR are contradictory. Judging the amount of viable tumour in these patients is problematic, but crucial to determine the intensity of further treatment. The value of positron emission tomography is still under investigation. Because the difference between doses of 30 and 40Gy might actually make a difference for the long-term toxicity of radiotherapy in some of the normal tissues and organs at risk (salivary glands, orbital structures, lung, heart, etc.), it appears prudent to resolve the open questions in prospective trials with careful documentation of side effects.

Murine stromal cells producing hyper-interleukin-6 and Flt3 ligand support expansion of early human hematopoietic progenitor cells without need of exogenous growth factors

Expansion of primitive hematopoietic progenitor cells (HPC) is a major challenge in stem cell biology. Stimulation by growth factors (GF) is essential for proliferation of HPC, while the role of stromal cell coculture for maintenance of progenitor/stem cell potential is unclear. We evaluated the potential of a murine stromal cell layer providing hematopoietic GF to support expansion of human CD34(+) cells. Murine MS-5 cells were transfected with the cDNA encoding huFlt3 ligand and the interleukin6/sinterleukin-6R fusion protein hyper-IL-6. Expansion of CFC and week6 CAFC was at least as efficient in transfected clones compared to control cocultures supported with exogenous GF. Cell numbers reached 17.5- to 62.3- (day 14) and 17.4- to 92.4-fold (day 21) of input cells. Expansion of CFU-GM/Mix was 4.0- to 12.8-fold (day 14) and 4.9- to 11.7-fold (day 21). Primitive week6 CAFC were expanded up to 6.5-fold (day 14) and 6.2-fold (day 21) without exogenous GF. When direct contact of HPC and stromal cells was inhibited, a loss of CFC and much more of CAFC potential was observed with unaffected overall cell proliferation. Here, we show the generation of GF producing murine stromal cells which efficiently support early hematopoiesis without exogenous GF. Direct stromal cell-HPC contact is advantageous for maintenance of differentiation potential.

Effects of imatinib on bone marrow engraftment in syngeneic mice

Chronic myeloid leukemia (CML) and a subset of acute lymphoblastic leukemias arise from the genetic reciprocal translocation t(9;22), forming the BCR-ABL fusion gene. These lead to the expression of the constitutively active tyrosine kinase BCR-ABL, which is the causative oncogene for these leukemias. Allogeneic bone marrow transplantation (BMT) or stem cell transplantation (SCT) is currently considered the only curative treatment for chronic myeloid leukemia (CML). Recently, the selective tyrosine kinase inhibitor imatinib mesylate (Glivec, formerly STI-571) has been shown to induce durable hematologic and major cytogenetic responses in a high percentage of patients with chronic phase CML. In patients with advanced disease remissions are transient and most patients relapse despite continued imatinib treatment. Some of these patients go on to receive allogeneic BMT or SCT, during which administration of imatinib is usually discontinued as it is believed to interfere with bone marrow engraftment. In this study, we examined the effect of imatinib on hematopoietic engraftment in a syngeneic mouse model. We found that imatinib has no significant influence on hematopoietic recovery in lethally irradiated mice in vivo. Thus, our results suggest that continued administration of imatinib in the course of BMT or SCT may be a feasible therapeutic regimen.

[Organizational prerequisites for multimodality therapy concepts]

The increasing use of multimodal therapies confronts clinics with the need to create new organisational structures. The high degree of specialisation necessitates that the separate disciplines seek ways of working closer together. This is particularly the case when staging results have to be evaluated and a multimodal therapy course chosen or when quality management issues and the coordination of different steps of a treatment are being considered. By establishing disease-oriented organisational structures and by institutionalizing interdisciplinary cooperation, e.g. in daily tumor board meetings and in fixed disease management teams, the organisational prerequisites for implementing multimodal therapies are created.

Cell cycle progression of chronic lymphocytic leukemia cells is controlled by cyclin D2, cyclin D3, cyclin-dependent kinase (cdk) 4 and the cdk inhibitor p27

B-CLL cells are arrested in G0/early G1 phase of the cell cycle and are characterized by a marked hyporesponsiveness towards a variety of polyclonal B cell activators. We have previously demonstrated that costimulation with CpG-ODN and IL-2 can overcome this proliferative defect. Cyclin D3 is the principal D-type cyclin which mediates G1 progression in normal B cells, but in B-CLL cells both cyclin D2 and cyclin D3, were strongly upregulated upon stimulation. Both cyclins were associated with cdk4 but not with cdk6, which is the catalytic partner of D-type cyclins in normal B cells. Moreover, immune complexes consisting of cyclin D2 and cdk4 or cyclin D3 and cdk4 were both functional and phosphorylated the RB protein in vitro. The cell cycle inhibitor p27 plays a pivotal role in cell cycle progression of B lymphocytes and has been shown to be overexpressed in B-CLL cells. P27 was rapidly downregulated in B-CLL cells even when stimulated with a non-CpG-ODN or IL-2 alone, while only moderate regulation could be observed in normal B cells. Taken together, our findings demonstrate that regulation of early cell cycle progression differs between B-CLL cells and normal B cells. These findings do not only contribute to the understanding of B-CLL pathophysiology, but might ultimately lead to the identification of new therapeutic targets.

Induction of a T helper cell response against the tumor-associated antigen HER2 using monocyte-derived dendritic cells

Tumor-reactive CD4(+) T helper (Th) cells play a criticalrole in antitumor immunity, due to their ability to induceCD8(+) T cell-mediated cytotoxic activity and humoralresponse. This study focuses on the in vitro generationand expansion of Th cells specific for the tumor-associatedantigen ;human epidermal growth factor receptor-2' (HER2). Aprotocol for efficient HER2 presentation was developed usingautologous monocyte-derived dendritic cells (DC) as antigenpresenting cells (APC) and purified HER2 protein as antigensource. Our data suggest that DC pulsed with recombinantprotein of the extracellular domain (ECD) of HER2 (ECD/HER2)induce an ECD/HER2-specific Th cell response. This finding mayfacilitate the development of immunotherapy regimens withoutrequiring defined immunogenic epitopes of the antigen.

Grb4/Nckbeta acts as a nuclear repressor of v-Abl-induced transcription from c-jun/c-fos promoter elements

Grb4 is an adaptor protein consisting of three src homology (SH) 3 domains and a single SH2 domain. We previously cloned Grb4 as a direct interacting partner of Bcr-Abl and v-Abl via the Grb4 SH2 domain. We now show that overexpression of Grb4 results in significant inhibition of v-Abl-induced transcriptional activation from promitogenic enhancer elements such as activator protein 1 (AP-1) and serum-responsive element (SRE). We demonstrate that the inhibitory activity of Grb4 is independent of the direct interaction of v-Abl and Grb4: a Grb4 mutant that lacks a functional SH2 domain shows an even more pronounced inhibition of AP-1/SRE. Further mutational analysis revealed that the first two SH3 domains primarily mediate the inhibitory function. The inhibitory activity of Grb4 is specific for c-jun/c-fos-regulated promoter elements and is located downstream of MEKK1 and JNK because co-expression of Grb4 resulted in down-regulation of MEKK1-induced AP-1 activity without affecting JNK activity. Thus, the nuclear pool of Grb4 is likely to mediate this inhibition. Indeed, cell fractionation and fluorescence microscopy studies revealed that the stronger inhibitory potential of the Grb4 SH2 mutant occurred in conjunction with increased nuclear localization of this mutant. Our results suggest a novel role for Grb4 in the inhibition of promitogenic enhancer elements such as 12-O-tetradecanoylphorbol-13-acetate-responsive element and SRE.

Regulation of hematopoietic growth factor production by genetically modified human bone marrow stromal cells expressing interleukin-1beta antisense RNA

Interleukin-1 (IL-1) plays a major role in the regulation of bone marrow stromal cell function and hematopoiesis. It is known to induce secretion of the hematopoietic growth factors granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage CSF (GM-CSF), IL-6, and IL-8 as well as IL-1 itself in stromal cells. We investigated the role of IL-1beta-mediated growth factor production in the human stromal cell line L88/5. Using liposome-mediated DNA transfer, two stromal cell transfectants that constitutively express IL-1beta antisense (AS) RNA were generated. Expression of IL-1beta AS RNA and IL-1beta RNA was determined by RT-PCR. The stromal cell transfectants were strongly impaired in their endogenous IL-1beta production, and this effect was present even when strong IL-1beta inducers, such as IL-1alpha and tumor necrosis factor-alpha (TNF-alpha), were used. Reduced endogenous IL-1beta levels had no effect on the constitutive production of IL-6, IL-8, and GM-CSF measured by ELISA. In contrast to lipopolysaccharide (LPS) stimulation, IL-1alpha-mediated stimulation of GM-CSF production was significantly reduced in AS transfectants. TNF-alpha induced GM-CSF production was also reduced. IL-6 and IL-8 production was increased in transfectants, suggesting a negative regulatory role of IL-1beta in L88/5. This new approach using AS technology to specifically target constitutive RNA expression will allow further characterization of the bone marrow cytokine network in normal and malignant hematopoiesis.

Rituximab therapy of patients with B-cell chronic lymphocytic leukemia

Rituximab (IDEC-C2B8) is a chimeric antibody that binds to the B-cell surface antigen CD20. Rituximab has significant activity in follicular non-Hodgkin lymphomas. Much less is known about the effects in chronic lymphocytic leukemia (CLL). We have initiated a phase II trial to evaluate the efficacy and safety of rituximab in patients with CD20+ pretreated CLL. To avoid the rituximab-associated toxicity, we restricted the tumor cell load, as measured by the number of circulating lymphocytes and the spleen size, in the first 2 cohorts of patients included in the study. Patients received 4 intravenous infusions of 375 mg/m2 once a week over a period of 1 month. Of the 28 patients evaluable for response, 7 patients showed a partial remission (National Cancer Institute criteria) lasting for a median of 20 weeks, with 1 patient still in remission after 71 weeks. Based on lymphocyte counts only, we found at least a 50% reduction of lymphocyte counts lasting for at least 4 weeks in 13 (45%) of 29 patients. Fifteen patients from 3 institutions were monitored for the immunophenotype profile of lymphocyte subsets. The number of CD5+CD20+ cells decreased significantly and remained low until day 28 after therapy. T-cell counts were not affected. With the exception of one rituximab-related death, adverse events in the remaining patients were mild. The results suggest that rituximab has clinical activity in pretreated patients with B-CLL. Toxicity is tolerable. Response duration after withdrawal of rituximab is rather short. Therefore, other modes of application and the combination with other agents need to be tested.

Two membrane-associated NiFeS-carbon monoxide dehydrogenases from the anaerobic carbon-monoxide-utilizing eubacterium Carboxydothermus hydrogenoformans

Two monofunctional NiFeS carbon monoxide (CO) dehydrogenases, designated CODH I and CODH II, were purified to homogeneity from the anaerobic CO-utilizing eubacterium Carboxydothermus hydrogenoformans. Both enzymes differ in their subunit molecular masses, N-terminal sequences, peptide maps, and immunological reactivities. Immunogold labeling of ultrathin sections revealed both CODHs in association with the inner aspect of the cytoplasmic membrane. Both enzymes catalyze the reaction CO + H(2)O --> CO(2) + 2 e(-) + 2 H(+). Oxidized viologen dyes are effective electron acceptors. The specific enzyme activities were 15,756 (CODH I) and 13,828 (CODH II) micromol of CO oxidized min(-1) mg(-1) of protein (methyl viologen, pH 8.0, 70 degrees C). The two enzymes oxidize CO very efficiently, as indicated by k(cat)/K(m) values at 70 degrees C of 1.3. 10(9) M(-1) CO s(-1) (CODH I) and 1.7. 10(9) M(-1) CO s(-1) (CODH II). The apparent K(m) values at pH 8.0 and 70 degrees C are 30 and 18 microM CO for CODH I and CODH II, respectively. Acetyl coenzyme A synthase activity is not associated with the enzymes. CODH I (125 kDa, 62.5-kDa subunit) and CODH II (129 kDa, 64.5-kDa subunit) are homodimers containing 1.3 to 1.4 and 1.7 atoms of Ni, 20 to 22 and 20 to 24 atoms of Fe, and 22 and 19 atoms of acid-labile sulfur, respectively. Electron paramagnetic resonance (EPR) spectroscopy revealed signals indicative of [4Fe-4S] clusters. Ni was EPR silent under any conditions tested. It is proposed that CODH I is involved in energy generation and that CODH II serves in anabolic functions.

The generation of both T killer and Th cell clones specific for the tumor-associated antigen HER2 using retrovirally transduced dendritic cells

Induction of antitumor immunity involves the presence of both CD8(+) CTLs and CD4(+) Th cells specific for tumor-associated Ags. Attempts to eradicate cancer by adoptive T cell transfer have been limited due to the difficulty of generating T cells with defined Ag specificity. The current study focuses on the generation of CTL and Th cells against the tumor-associated Ag HER2 using autologous dendritic cells (DC) derived from CD34(+) hematopoietic progenitor cells which have been retrovirally transduced with the human epidermal growth factor receptor 2 (HER2) gene. HER2-transduced DC elicited HER2-specific CD8(+) CTL that lyse HER2-overexpressing tumor cells in context of distinct HLA class I alleles. The induction of both HLA-A2 and -A3-restricted HER2-specific CTL was verified on a clonal level. In addition, retrovirally transduced DC induced CD4(+) Th1 cells recognizing HER2 in context with HLA class II. HLA-DR-restricted CD4(+) T cells were cloned that released IFN-gamma upon stimulation with DC pulsed with the recombinant protein of the extracellular domain of HER2. These data indicate that retrovirally transduced DC expressing the HER2 molecule present multiple peptide epitopes and subsequently elicit HER2-specific CTL and Th1 cells. The method of stimulating HER2-specific CD8(+) and CD4(+) T cells with retrovirally transduced DC was successfully implemented for generating HER2-specific CTL and Th1 clones from a patient with HER2-overexpressing breast cancer. The ability to generate and expand HER2-specific, HLA-restricted CTL and Th1 clones in vitro facilitates the development of immunotherapy regimens, in particular the adoptive transfer of both autologous HER2-specific T cell clones in patients with HER2-overexpressing tumors without the requirement of defining immunogenic peptides.

gp130-stimulating designer cytokine Hyper-interleukin-6 synergizes with murine stroma for long-term survival of primitive human hematopoietic progenitor cells

OBJECTIVE

Experimental strategies for ex vivo expansion of human hematopoietic stem/progenitor cells involve the use of exogenous cytokines as well as direct interaction with stromal elements. We examined the use of the interleukin-6/soluble interleukin-6 receptor (IL-6/sIL-6R) fusion protein Hyper-IL-6 (H-IL-6), which interacts directly with gp130, in conjunction with stromal support for expansion of human progenitors.

MATERIALS AND METHODS

Peripheral blood CD34+ cells were cultured on the murine stromal cell line FBMD1 or in suspension for up to 28 days with different cytokines. Cells were evaluated at various time points for phenotype, proliferative and clonogenic capacity, and long-term hematopoietic activity.

RESULTS

The combination of Flt3 ligand and H-IL-6 was markedly more effective than Flt3 ligand and IL-6/sIL-6R for expansion of CD34+ cells in suspension culture and on FBMD1. Addition of kit ligand but not thrombopoietin to Flt3 ligand and H-IL-6 significantly augmented proliferation and enhanced colony formation three-fold. However, long-term cobblestone area-forming cell assays indicated that although multipotent progenitors were maintained up to 21 days on FBMD1 in the presence of Flt3 ligand alone and were amplified three-fold by addition of H-IL-6, CD34+ cells cultured in the absence of stromal support rapidly lost their cobblestone area-forming cell potential. Immunophenotyping revealed that stromal support prevented up-regulation of IL-6R on CD34+ cells, which was induced within 3 days in stroma-free cultures and was enhanced in the presence of kit ligand. Delayed addition of H-IL-6 to the cultures resulted in reduced proliferation and colony-forming unit potential.

CONCLUSION

H-IL-6 synergizes with stromal elements to effectively enhance proliferation and maintenance of primitive hematopoietic progenitors under prolonged ex vivo culture conditions.

Effect of immunostimulatory CpG-oligonucleotides in chronic lymphocytic leukemia B cells

Bacterial DNA and phosphothioate oligonucleotides containing a CpG motif (CpG-ODN) can activate cells of the immune system such as monocytes, dendritic cells and B cells. Protective immune responses against pathogens and tumor cells were observed in murine models when mice were treated with CpG-ODN. Recent results have demonstrated strong activation of human immune cells as well. Apart from stimulating cells of the immune system, CpG ODN have many direct effects on B-CLL cells such as upregulation of costimulatory molecules, cell cycle entry and upregulation of potential target antigens for antibody therapy. Therefore, CpG-ODN appear to be attractive compounds to be included into new therapeutic strategies like tumor cell vaccination and adoptive T cell transfer or therapy with monoclonal antibodies. In this review, the effects of CpG-ODN on B-CLL cells are summarized and potential therapeutic applications of CpG-ODN in chronic lymphocytic leukemia are discussed.

Pitfalls in imaging Hodgkin's disease with computed tomography and positron emission tomography using fluorine-18-fluorodeoxyglucose

We report on a patient with Hodgkin's disease who presented with hypodense splenic lesions and corresponding increased glucose metabolism in FDG-PET imaging, four months after completion of initial treatment, suggestive of early relapse. Serological testing for toxoplasma gondii, however, showed evidence of a recently reactivated or newly acquired infection. Three weeks after immediate antibiotic treatment with Daraprime and Sulfadiazin, the splenic lesions had completely resolved. Additionally, serological titers for toxoplasma gondii were normalized and whole body FDG-PET imaging showed no metabolic activity. Although the positive predictive value of PET imaging to indicate lymphoma is reported to be higher than CT, hypermetabolic lesions are not specific for malignant tissue. Whereas benign tumors typically show low glucose metabolism, activated granulocytes and macrophages may display significantly increased glucose consumption. In conclusion, our case report shows that although therapeutic decisions are often based on the results of imaging modalities, the taking of a detailed history and the acquisition of histological confirmation of the suspected lymphoma relapse are also advisable where possible. Cellular immunodeficiency can result in severe infections even in patients with intermediate stage Hodgkin's lymphoma in remission after combined modality treatment. Therefore, despite the high sensitivity of FDG-PET imaging for the detection of recurrent lymphoma, the differential diagnosis of infectious lesions should be kept in mind, in particular in immunocompromised patients.