Comparison of gallium and PET scans at diagnosis and follow-up of pediatric patients with Hodgkin lymphoma

[Rebound (reactive) thymic hyperplasia after chemotherapy in children with lymphoma]

INTRODUCTION

Thymic regrowth after chemotherapy treatment has been reported in children with lymphoma, and in order to avoid misdiagnosing these cases as relapses, physicians should become familiar with rebound (reactive) thymic hyperplasia (RTH) and remain aware of its possible occurrence. We aimed to estimate the prevalence of RTH in children with lymphoma after completion of chemotherapy and to evaluate the clinical characteristics, outcomes, and the findings of computed tomography (CT) and gallium-67 (GA-67) scans in these patients.

PATIENTS AND METHODS

We conducted a retrospective cross-sectional study by reviewing the health records of children with a lymphoma diagnosis managed at an outpatient paediatric oncology clinic in Jeddah, Saudi Arabia.

RESULTS

Rebound thymic hyperplasia was detected in 51.9% of the lymphoma patients (14/27). It developed a median of 2.5 months after completion of chemotherapy (range, 2.0-4.25 months). Patients with RTH had significantly shorter treatment durations, and we found no significant differences between patients with and without RTH in sex, age at diagnosis, type of lymphoma or type of treatment received. All patients with RTH were asymptomatic, and routine laboratory tests did not detect any abnormalities in them. The findings of CT and GA-67 scans were highly suggestive of RTH. None of the patients with RTH had a recurrence, and RTH resolved spontaneously within a median of 6 months (range, 4.0-11.0).

CONCLUSION

RTH was detected in ∼50% of children with lymphoma after completion of chemotherapy. A clinical evaluation and laboratory tests combined with imaging by CT and GA-67 can help identify RTH and rule out other lesions elsewhere.

Interim Functional Imaging Is an Independent Predictor of Progression-free Survival in Advanced Classical Hodgkin Lymphoma - A Real-world Analysis

BACKGROUND

Response-adapted therapy in advanced classical Hodgkin lymphoma (cHL) using interim functional imaging (IFI) is under active investigation.

PATIENTS AND METHODS

We retrospectively examined patients with advanced cHL receiving 2 front-line regimens stratified by IFI results at our institution. Time to endpoint analysis was estimated using the method of Kaplan-Meier with log ranks. Cox regression modeling was computed for multivariable analysis.

RESULTS

A total of 124 patients with advanced cHL with a median follow up of 40.9 months were included. A total of 84 (67.7%) received ABVD (doxorubicin, bleomycin, vinblastine, and dacarbazine), whereas the remaining 40 (32.3%) received ABVD/eBEACOPP (escalated bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine, and prednisone). A positive IFI was seen in 36 (29%) patients. The corresponding 3-year progression free survival (PFS) stratified by IFI was 81.7% (95% confidence interval [CI], 70.1%-88.8%) versus 48.3% (95% CI, 30.4%-64.1%) (P < .0001) for patients with negative or positive scan, respectively. Escalation to eBEACOPP from ABVD following a positive IFI resulted in a significantly higher 3-year PFS at 58.7% (95% CI, 0.3-0.79) versus 39.7% (95% CI, 0.18-0.61) respectively (P = .00015). Overall survival (OS) was similar across the groups (P = .44) irrespective of therapy received. At multivariable analysis, IFI was the only predictor of PFS with a hazard ratio of 4.6 (95% CI, 1.9-10.8; P = .0008) whereas therapy escalation had a hazard ratio of 0.66 (95% CI, 0.14-3.4; P = .62).

CONCLUSION

IFI is an independent predictor of PFS in advanced cHL and can guide therapeutic decisions in the real world. Given the inferior outcome seen in patients with a positive IFI, novel approaches of therapy are warranted.

Nonossifying fibroma: A possible pitfall in F18-FD-PET/CT imaging of Hodgkin's disease

A 14-year-old girl was examined for a right lateral neck swelling and radiographic mediastinal widening. Biopsy of a right supraclavicular lymph node demonstrated the nodular sclerosing form of Hodgkin's lymphoma. An 18F-fluorodeoxyglucose-positron emission tomography/computed tomography (F18-FDG-PET/CT) study showed several pathological areas of lymph-node uptake in the upper mediastum and right distal tibia. Radiography of the tibia revealed a nonossifying fibroma in the site corresponding to the distal tibial uptake. The PET appearance of benign fibro-osseous lesions may be similar to those of skeletal metastases. Information obtained by the CT component of the PET/CT study and by conventional radiography can be useful in preventing erroneous interpretations of F18-FDG-PET uptake.

The role of FDG-PET/CT in the evaluation of residual disease in paediatric non-Hodgkin lymphoma

(18) F-labelled-fluorodeoxyglucose positron emission tomography (FDG-PET) findings are challenging to interpret for residual disease versus complete response in paediatric patients with non-Hodgkin lymphoma (NHL). A biopsy is often warranted to confirm the presence or absence of viable tumour if there is clinical or radiographic evidence of residual disease. In this study, we compared conventional imaging and FDG-PET/computerized tomography (CT) findings with biopsy results in 18 children with NHL. Our goal was to provide additional data to establish more reliable criteria for response evaluation. Residual disease was suspected after conventional imaging alone in eight patients, after FDG-PET/CT alone in three and after both modalities in seven patients. Biopsy confirmed the presence of viable tumour in two patients. Two additional patients experienced progressive disease or relapse. The sensitivity and negative predictive value of FDG-PET/CT using the London criteria to indicate residual tumour detectable by biopsy were 100%, but specificity was low (60%), as was the positive predictive value (25%). Thus, in this study, a negative FDG-PET/CT finding was a good indicator of complete remission. However, because false-positive FDG-PET/CT findings are common, biopsy and close monitoring are required for accurate determination of residual disease in individual patients.

Update on pediatric leukemia and lymphoma imaging

Together, leukemia and lymphoma account for half of all childhood malignancies. Leukemia and lymphoma arise from similar cell lines and can have overlapping imaging features; however, the clinical presentation, imaging strategies, and treatment protocols can vary substantially based on the specific subtype. Although imaging does not play a central role in staging or monitoring disease in childhood leukemia, findings on imaging may be the first indication of the diagnosis. Advanced imaging, especially positron emission tomography/computed tomography, has moved to the forefront of staging and treatment response evaluation in Hodgkin's disease and non-Hodgkin's lymphoma. Imaging also plays a key role in evaluating the myriad of treatment complications that are commonly seen with chemotherapy and associated neutropenia. Future efforts will be largely focused on decreasing radiation exposure to these children, utilizing reduced or radiation-free modalities, such as positron emission tomography/magnetic resonance and diffusion-weighted whole-body imaging with background suppression, as well as refining surveillance imaging strategies. The purpose of this article is to briefly review the classification of pediatric leukemia and lymphoma, illustrate common imaging findings at presentation throughout the body, describe staging and therapeutic response evaluation, and show a spectrum of commonly encountered complications of treatment.

The utility of FDG PET in diagnosis and follow-up of lymphoma in childhood

Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL) are among the most common malignancies of childhood. (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) can be employed for accurate staging, treatment planning, and response assessment in pediatric patients with lymphomas, taking advantage of the increased FDG uptake of the malignant cells, secondary to their increased metabolic needs. FDG PET has higher sensitivity than other imaging modalities to detect nodular or diffuse lesions and higher sensitivity than bone marrow biopsy to detect bone marrow infiltration. FDG PET consists of an invaluable imaging modality during evaluation and treatment of pediatric lymphomas.

Review of Clinical Applications of Fluorodeoxyglucose-PET/Computed Tomography in Pediatric Patients with Lymphoma

[(18)F]fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) imaging is routinely used in the initial diagnosis and response assessment during and immediately after therapy, as well as in the follow-up surveillance. FDG PET/CT outperforms diagnostic CT and other conventional imaging modalities in the evaluation of pediatric patients with lymphoma, with higher sensitivity and specificity, leading to more accurate staging/restaging and modifications of therapeutic strategies. Resolution of FDG-avid lesions in the early post-therapy phase often indicates good response to treatment and better prognosis. FDG PET/CT also outperforms bone marrow biopsy in detecting bone marrow infiltration of lymphoma.

Leukemia and lymphoma

Leukemia and lymphoma are the most common and third most common pediatric malignancies, respectively, and share cell lineages, but the clinical and imaging manifestations of these malignancies vary substantially. Along with providing pertinent details on classification, epidemiology, and treatment, this article reviews the current roles of imaging in the management of childhood leukemia and lymphoma, with attention to diagnosis, staging, risk stratification, therapy response assessment, and surveillance for disease relapse and adverse effects of therapy. Advances in functional imaging are also discussed to provide insights into future applications of imaging in the management of pediatric patients with leukemia and lymphoma.

Role of FDG-PET in the definition of involved-field radiation therapy and management for pediatric Hodgkin's lymphoma

PURPOSE

To evaluate positron emission tomography-computed tomography (PET-CT) influences in involved-field radiation therapy (IFRT) field design in pediatric Hodgkin's lymphoma (HL).

MATERIALS AND METHODS

From June 2003 to February 2008, 30 pediatric HL patients were treated at Children's Healthcare of Atlanta (CHOA) and Emory University Department of Radiation Oncology with both chemotherapy and IFRT. Diagnostic contrast-enhanced CT and PET-CT were coregistered using image fusion software. Both were reviewed for all potential sites of involvement and correlated to determine concordance and discordance. They were used in IFRT planning to determine the influence of PET-CT on target volumes and field design.

RESULTS

There were 546 regions analyzed by both PET and CT modalities. Image sets were concordant in 468 regions and discordant in 78, yielding 86% concordance overall. Analysis by weighted κ statistic showed "intermediate to good" fit overall and for nodal sites, but "poor" agreement for extranodal sites. If discordant, a site was most likely PET+/CT-. Integration of PET information caused a change in staging in 15 (50%) patients, 7 upstaged and 8 downstaged. The IFRT volumes were adjusted on the basis of initial PET-CT finding in 21 (70%) patients, with 32 sites added and 15 excluded. There were four relapses, only one outside IFRT fields, but all were successfully salvaged.

CONCLUSION

PET-CT represents an important tool in the management of pediatric patients with HL and has a substantial influence on both initial staging and radiation treatment target definition and field design.

FDG PET and PET/CT in the Management of Pediatric Lymphoma Patients

Fluorodeoxyglucose (FDG) PET has an ever-increasing role in the management of Hodgkin's and non-Hodgkin's lymphomas, which has been demonstrated in numerous studies in the adult population. In children and adolescents, however, only a limited number of studies have investigated the role of FDG PET in lymphoma. This article reviews the currently available literature on the clinical application of FDG PET in the management of childhood lymphoma. The authors believe that FDG PET (and especially PET/CT) is a valuable imaging modality in the initial diagnosis, response assessment, and post-therapy residual evaluation of Hodgkin's and FDG-avid non-Hodgkin's lymphomas in children and adolescents, and will have a significant impact on the clinical management of pediatric lymphoma.