False-positive restaging PET scans involving the spleen in two patients with aggressive non-Hodgkin lymphoma

Post-Chemotherapy Histiocyte-Rich Pseudotumors: Radiologic and Endoscopic Mimics of Residual Lymphoma

Development of post-chemotherapy histiocyte-rich pseudotumor (PHP) is an underrecognized event following therapy in lymphoma patients and may mimic residual tumor using current therapy monitoring protocols. We report a series of 5 patients with PHP along with a review of the literature. In our series, we describe 3 patients with persistent hypermetabolic masses by positron emission tomography-computed tomography, one with persistent terminal ileal nodules on endoscopy, and one with bone marrow involvement, a site not associated with mass-like disease. Twenty-three patients with long-term follow-up were identified from our series and review of the literature. Forty-four percent of patients received additional therapy, and only 4% of patients died of lymphoma. This study illustrates that PHPs are not identified using current lymphoma therapy monitoring algorithms and may result in overtreatment with risk for additional therapy-related complications. The need for confirmatory tissue biopsy in this setting is recommended.

Postchemotherapy Histiocyte-rich Pseudotumor Mimicking Residual Lymphoma: A Report of 11 Cases Correlating Clinicopathologic and Radiologic Findings

Postchemotherapy histiocyte-rich pseudotumor is a rare event in lymphoma patients and can cause elevated metabolic activity on positron emission tomography-computed tomography scan mimicking residual tumor. Here, we reported 11 lymphoma cases showing mass-like lesions with increased fluorodeoxyglucose uptake after chemotherapy. These postchemotherapy lesions occurred in various anatomic sites including spleen, mediastinum, lymph node, and other tissue locations, concerning for refractory or residual lymphoma. Their median size was 2.7 cm (range, 1.4 to 7.7 cm) and the median standardized uptake value on positron emission tomography-computed tomography was 10.6 (range, 5.2 to 13.8). Histologic examination of these lesions demonstrated reactive changes mainly composed of histiocyte-rich proliferation without viable lymphoma. Fat necrosis, cholesterol cleft, and calcium deposit were also commonly observed. After biopsies, 3 patients received additional chemotherapy, 2 had stem cell transplant with adjuvant chemotherapy or radiation, 1 had surgical excision, and the remaining 5 patients did not receive any further treatment. Follow-up imaging studies showed the resolved or decreased fluorodeoxyglucose activities in all patients including those without additional treatments, consistent with benign/reactive nature of these pseudotumor lesions. This study illustrates postchemotherapy mass-like lesions with elevated metabolic activity do not always represent residual disease and provides awareness of correlation between radiologic and histologic features of these lesions to avoid misinterpretation and overtreatment of lymphoma patients after chemotherapy.

[Clinical features of 11 cases of primary bone lymphoma]

目的

探讨原发性骨淋巴瘤患者的临床特征、治疗及预后。

方法

回顾性分析11例原发性骨淋巴瘤患者的临床资料，对其临床特征，诊治过程及预后进行分析总结。

结果

11例患者中女7例，男4例，中位发病年龄45岁，仅1例患者以无痛性肿块起病，其余均以骨痛为首发症状，主要病理类型为弥漫大B细胞淋巴瘤和间变大细胞淋巴瘤。Ann Arbor临床分期ⅠE期3例，ⅡE期2例，ⅣE期6例。6例患者采取化疗联合放疗，2例行骨关节置换术联合化疗，3例选择单纯化疗。11例患者经初始治疗后5例达完全缓解，4例达部分缓解，2例疾病稳定。中位随访时间为21（6~58）个月，中位无进展生存期为17（5~58）个月。

结论

原发性骨淋巴瘤诊断时多为晚期，临床表现及影像学检查缺乏特异性，目前治疗主要采取以化疗为主的综合治疗，预后相对较好。

Prognostic values of interim and post-therapy 18F-FDG PET/CT scanning in adult patients with Burkitt's lymphoma

Background

The prognostic values of interim and post-therapy fluorine-18-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET) and PET/computed tomography (CT) scanning have been confirmed in several subtypes of lymphoma. However, its prognostic value in Burkitt’s lymphoma has not been clearly defined. The aim of the present study was to assess the prognostic value of PET/CT scanning during different treatment processes of Burkitt’s lymphoma.

Methods

A total of 29 adult patients with newly diagnosed Burkitt’s lymphoma were retrospectively involved in this study; of them, 23 patients underwent baseline PET/CT, 15 patients underwent mid-therapy PET/CT after 1–4 cycles of chemotherapy, and 17 patients underwent post-therapy PET/CT after all planned first-line chemotherapy cycles. Mid-therapy and post-therapy PET/CT results (positive vs. negative) were visually interpreted according to the criteria of the International Harmonization Project. The reduction in the maximum standardizes uptake values (∆SUVmax) of 25%, 50%, and 75% were regarded as cutoff points. Overall survival (OS) and progression-free survival (PFS) were regarded as the major endpoints.

Results

The median OS and PFS were 27.6 months (range 6.5–78.3 months) and 27.2 months (range 3.0–78.3 months), respectively. The median SUVmax of the baseline PET/CT was 18.3 (range 1.6–35.9), whereas the median SUVmax of the mid-therapy and post-therapy PET/CT decreased to 4.0 (range 0–17.6) and 3.0 (range 0–14.5), respectively. The patients’ Eastern Cooperative Oncology Group (ECOG) scores (<2 vs. ≥2) were significantly associated with the baseline PET/CT SUVmax. The mid-therapy and post-therapy PET/CT results (positive vs. negative) showed no significant association with OS or PFS. The optimal cutoff ∆SUVmax from the baseline to the post-therapy PET/CT that could predict a change in OS in patients with Burkitt’s lymphoma was 50% (P = 0.019).

Conclusions

¹⁸F-FDG uptake was intense in Burkitt’s lymphoma, and there was a significant reduction in SUVmax during the interim and post-therapy PET/CT procedures. A ∆SUVmax of greater than 50% was a favorable cutoff point to predict the OS of Burkitt’s lymphoma patients.

Use of 18F-FDG PET/CT imaging for evaluation of patients with primary splenic lymphoma

Primary splenic lymphoma (PSL) is a rare disease, and its management differs from other splenic malignancies. The purpose of the present study was to evaluate the role of 18F-FDG PET/CT in patients with PSL.

METHODS

We retrospectively evaluated the data of 17 patients with PSL (median age, 46 years; range, 3-64) who had undergone 50 18F-FDG PET/CT studies. Of the 50 PET/CTs, 15 were done for primary diagnosis/staging and 35 were done for restaging. PET/CT images were evaluated both qualitatively and quantitatively [maximum standardized uptake value (SUVmax)]. Combination of clinical/imaging follow-up and/or histopathologic diagnosis was taken as reference standard.

RESULTS

Of the total 50 F-FDG PET/CT studies, 27 studies (54%) were positive and 23 (46%) were negative for disease. PET/CT was true positive in 25 studies, true negative in 22 studies, false positive in 2 studies, and false negative in 1 study. Overall, per study-based sensitivity was 96.2%, specificity was 91.7%, and accuracy was 94%. In those studies performed for diagnosis/staging (15/50), PET/CT was true positive in all 15, with an accuracy of 100%. In those studies performed for restaging (35/50), sensitivity was 90.9%, specificity was 91.7%, and accuracy was 91.4%. No significant difference was seen in the accuracy of PET/CT between staging and restaging groups (P=0.601). On 18F-FDG PET/CT, splenic involvement was seen in 24 studies, lymph nodal involvement in 5 studies, liver involvement in 3 studies, and bone marrow involvement in 1 study. More than one site of disease was seen in 9 PET/CT studies. On semiquantitative analysis, the overall mean splenic lesion SUVmax was 6.9±7.9 (median, 4.6; range, 1.3-29). The mean value of ratio of SUVmax of splenic lesions and SUVliver was 4.4±5.5 (median, 2.4; range, 0.9-24.2). On comparison of areas under the curve, the mean value of ratio of SUVmax of splenic lesions and SUVliver was found to be superior to SUVmax alone for this differentiation of involvement from normal spleen (P=0.018).

CONCLUSION

18F-FDG PET/CT seems useful in patients with primary splenic lymphoma and shows high diagnostic accuracy.

Qualitative visual trichotomous assessment improves the value of fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography in predicting the prognosis of diffuse large B-cell lymphoma

Introduction

Fluorine-18 fluorodeoxyglucose (¹⁸ F-FDG) positron emission tomography/computed tomography (PET/CT) is a powerful tool for monitoring the response of diffuse large B-cell lymphoma (DLBCL) to therapy, but the criteria to interpret PET/CT results remain under debate. We investigated the value of post-treatment PET/CT in predicting the prognosis of DLBCL patients when interpreted according to qualitative visual trichotomous assessment (QVTA) criteria compared with the Deauville criteria.

Methods

In this retrospective study, final PET/CT scans of DLBCL patients treated with rituximab-based regimens between October 2005 and November 2010 were interpreted using the Deauville and QVTA criteria. Survival curves were estimated using Kaplan-Meier analysis and compared using the log-rank test.

Results

A total of 253 patients were enrolled. The interpretation according to the Deauville criteria revealed that 181 patients had negative PET/CT scan results and 72 had positive results. The 3 year overall survival (OS) rate was significantly higher in patients with negative scan results than in those with positive results (91.6 % vs. 57.5 %, P < 0.001). The 72 patients with positive scan results according to the Deauville criteria were divided into two groups by the interpretation according to the QVTA criteria: 29 had indeterminate results, and 43 had positive results. The 3 year OS rate was significantly higher in patients with indeterminate scan results than in those with positive results (91.2 % vs. 33.5 %, P < 0.001) but was similar between patients with negative and indeterminate scan results (91.6 % vs. 91.2 %, P = 0.921).

Conclusions

Compared with the Deauville criteria, using the QVTA criteria for interpreting post-treatment PET/CT scans of DLBCL patients is likely to reduce the number of false positive results. The QVTA criteria are feasible for therapeutic outcome evaluation and can be used to guide risk-adapted therapy.

Primary and secondary bone lymphomas

Recent studies have contributed to the enhancement of clinical and molecular knowledge on bone lymphomas, a group of rare malignancies with particular characteristics. Nevertheless, several questions remain unanswered and the level of evidence supporting some diagnostic and therapeutic decisions remains low. Currently, three different forms of bone lymphomas can be distinguished: the primary bone lymphoma, consisting of a single bone lesion with or without regional lymphadenopathies; the polyostotic lymphoma, consisting of multifocal disease exclusively involving the skeleton; and the disseminated lymphoma with secondary infiltration of the skeleton. The first two forms exhibit a good prognosis, requiring treatments similar to those commonly used for nodal lymphomas of the same category, but several issues regarding the role of surgery and local control of the disease, the sequence of treatment, radiation volumes and doses, management of pathological fractures and prevention of late sequelae deserve particular attention. Due to its rarity, prospective trials exclusively focused on bone lymphomas appear unrealistic, thus, critical revision of our own experience and analyses of large cumulative series as well as molecular studies on archival cases remain valid alternatives to improve our knowledge on this obscure lymphoproliferative malignancy. The present review is based on the analysis of the largest available database of bone lymphomas established under the sponsorship of the International Extranodal Lymphoma Study Group (IELSG) as well as on the critical revision of related literature. We provide recommendations for diagnosis, staging, treatment, and response assessment of these patients in everyday practice as well as for the management of special conditions like pathological fractures, indolent forms and central nervous system prophylaxis.

Use of subsequent PET/CT in diffuse large B-cell lymphoma patients in complete remission following primary therapy

Interim 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (I-PET/CT) is a powerful tool for monitoring the response to therapy in diffuse large B-cell lymphoma (DLBCL). This retrospective study aimed to determine when and how to use I-PET/CT in DLBCL. A total of 197 patients treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) were enrolled between October 2005 and July 2011; PET/CT was performed at the time of diagnosis (PET/CT0), after 2 and 4 cycles of chemotherapy (PET/CT2 and PET/CT4, respectively), and at the end of treatment (F-PET/CT). According to the International Harmonization Project for Response Criteria in Lymphoma, 110 patients had negative PET/CT2 scans, and 87 had positive PET/CT2 scans. The PET/CT2-negative patients had significantly higher 3-year progression-free survival rate (75.8% vs. 38.2%) and 3-year overall survival rate (93.5% vs. 55.6%) than PET/CT2-positive patients. All PET/CT2-negative patients remained negative at PET/CT4, but 3 were positive at F-PET/CT. Among the 87 PET/CT2-positive patients, 57 remained positive at F-PET/CT, and 32 progressed during chemotherapy (15 at PET/CT4 and 17 at F-PET/CT). Comparing PET/CT4 with PET/CT0, 7 patients exhibited progression, and 8 achieved partial remission. Comparing F-PET/CT with PET/CT0, 10 patients exhibited progression, and 7 achieved partial remission. In conclusion, our results indicate that I-PET/CT should be performed after 2 rather than 4 cycles of immunochemotherapy in DLBCL patients. There is a limited role for subsequent PET/CT in the detection of relapse in PET/CT2-negative patients, but repeat PET/CT is required if the PET/CT2 findings are positive.

Prognostic value of interim (18)F-FDG PET/CT in diffuse large B-cell lymphoma

OBJECTIVE

Diffuse large B-cell lymphoma (DLBCL) is a heterogeneous disease. The prognostic factor currently used is not accurate enough to predict the outcomes of patients with DLBCL. The prognostic significance of interim PET/CT in DLBCL remains controversial. The aim of this study is to determine the predictive value of interim (18)F-FDG PET/CT after first-line treatment in patients with DLBCL.

METHODS

Thirty-two patients with DLBCL underwent baseline, interim and post-treatment (18)F-FDG PET/CT scans. Imaging results were analyzed for the survival of patients via software SPSS 13.0, retrospectively.

RESULTS

Thirty-one of the 32 patients were treated with R-CHOP regimen, and interim (18)F-FDG PET/CT of 24 patients was performed after 2 cycles of treatment. After a median follow-up period of 16.7 months, the 2-year progression-free survival (PFS) rates were significantly different between the groups above and below SUV(max) cut-off value of 2.5 (P=0.039). No significant differences were found in the 2-year PFS rates if SUV(max) cut-off values were set as 2.0 and 3.0, respectively (P=0.360; P=0.113).

CONCLUSIONS

Interim PET/CT could predict the prognosis of DLBCL patients with the SUV(max) cut-off value of 2.5, but more clinical data should be concluded to confirm this conclusion.

KEY WORDS

Fludeoxyglucose F18; lymphoma; large cell; diffuse; prognosis; standard utility value.

Interim 18-FDG-PET/CT failed to predict the outcome in diffuse large B-cell lymphoma patients treated at the diagnosis with rituximab-CHOP

Role of interim-PET (I-PET) in diffuse large B-cell Lymphoma (DLBCL) is controversial. To determine predictive value of I-PET on progression-free survival (PFS), we enrolled 88 first-line DLBCL patients treated with 6-8 R-CHOP courses regardless of I-PET. PET/CT were performed at diagnosis, after 2 to 4 courses and at the end of therapy with central reviewing according to visual dichotomous criteria. Results are as follows: I-PET, 72% negative, 28% positive; final-PET (F-PET), 88% negative, 12% positive; clinical complete response 90%. Concordance between clinical response and F-PET negativity was 97% because of 2 false positive. With a median follow-up of 26.2 months, 2-year overall survival and PFS were 91% and 77%, respectively. Two-year PFS for I-PET and F-PET negative versus positive were as follows: I-PET 85% versus 72% (P = .0475); F-PET 83% versus 64% (P < .001). Because of a small number of events, 2 independent bivariate Cox models were tested for PFS. In model 1, F-PET contradicted I-PET (hazard ratio [HR] = 5.03, P = .015 vs 1.27, P = 691); in model 2, F-PET (HR = 4.54) and International propnostic Index score (HR = 5.36, P = .001) remained independent prognostic factors. In conclusion, positive I-PET is not predictive of a worse outcome in DLBCL; larger prospective studies and harmonization of I-PET reading criteria are needed.

Risk-adapted dose-dense immunochemotherapy determined by interim FDG-PET in Advanced-stage diffuse large B-Cell lymphoma

PURPOSE In studies of diffuse large B-cell lymphoma, positron emission tomography with [(18)F]fluorodeoxyglucose (FDG-PET) performed after two to four cycles of chemotherapy has demonstrated prognostic significance. However, some patients treated with immunochemotherapy experience a favorable long-term outcome despite a positive interim FDG-PET scan. To clarify the significance of interim FDG-PET scans, we prospectively studied interim FDG-positive disease within a risk-adapted sequential immunochemotherapy program. PATIENTS AND METHODS From March 2002 to November 2006, 98 patients at Memorial Sloan-Kettering Cancer Center received induction therapy with four cycles of accelerated R-CHOP (rituximab + cyclophosphamide, doxorubicin, vincristine, and prednisone) followed by an interim FDG-PET scan. If the FDG-PET scan was negative, patients received three cycles of ICE (ifosfamide, carboplatin, and etoposide) consolidation therapy. If residual FDG-positive disease was seen, patients underwent biopsy; if the biopsy was negative, they also received three cycles of ICE. Patients with a positive biopsy received ICE followed by autologous stem-cell transplantation. RESULTS At a median follow-up of 44 months, overall and progression-free survival were 90% and 79%, respectively. Ninety-seven patients underwent interim FDG-PET scans; 59 had a negative scan, 51 of whom are progression free. Thirty-eight patients with FDG-PET-positive disease underwent repeat biopsy; 33 were negative, and 26 remain progression free after ICE consolidation therapy. Progression-free survival of interim FDG-PET-positive/biopsy-negative patients was identical to that in patients with a negative interim FDG-PET scan (P = .27). CONCLUSION Interim or post-treatment FDG-PET evaluation did not predict outcome with this dose-dense, sequential immunochemotherapy program. Outside of a clinical trial, we recommend biopsy confirmation of an abnormal interim FDG-PET scan before changing therapy.

Clinical significance of diffusely increased splenic uptake on FDG-PET

Diffusely increased uptake is more commonly observed than focal uptake in the spleen on a whole-body [F] fluorodeoxyglucose-positron emission tomography/computed tomography. The significance of diffusely increased splenic uptake varies in different clinical settings. On a pre-therapeutic scan for lymphoma, splenic uptake, greater than hepatic uptake, is a relative reliable indication of lymphomatous involvement of the spleen, unless the patient has a history of recent cytokine administration. In HIV infection, increased splenic uptake is usually noted in the early stage of the disease, which could reflect massive stimulation of B-cells in the spleen by nonreplicating antigenic material. Diffusely increased splenic uptake may also be present in sarcoidosis, malaria, and many inflammatory or hematopoietic diseases. Therapeutic-related reactive splenic uptake concurrent with bone marrow uptake is often secondary to administration of granulocyte colony-stimulating factor for myelosuppression or high-dose interferon-alpha-2b adjuvant therapy for melanoma.

Postchemotherapy histiocyte-rich pseudotumor involving the spleen

We report 2 cases of splenic postchemotherapy histiocyte-rich pseudotumor. Each patient had a history of diffuse large B-cell lymphoma, treated with multiagent chemotherapy. Computed tomography scans performed on both patients showed splenic masses. A positron emission tomography scan performed on 1 patient showed increased metabolic activity. The preoperative diagnosis in both patients was recurrent lymphoma, prompting splenectomy. The splenectomy specimens showed multiple, tan-white, firm nodules, up to 3.5 cm in diameter, that were histologically composed of central necrotic B cells (CD20+/CD3-), consistent with necrotic lymphoma, surrounded by numerous lipid-laden (xanthomatous) histiocytes. Clinical staging studies at the time of splenectomy showed no other sites of disease. We conclude that these histologic and immunophenotypic findings represent chemotherapy-induced tumor necrosis with a florid histiocytic reaction mimicking residual viable lymphoma. Others have used descriptive terminology or the term xanthomatous pseudotumor for these lesions that have been only rarely reported in the spleen previously.

18F-FDG PET and PET/CT in Burkitt's lymphoma

OBJECTIVE

To explore the value of (18)F fluorodeoxy-glucose (FDG) positron emission tomography (PET) in Burkitt's lymphoma.

METHODS

All Burkitt's lymphoma patients referred for FDG PET or FDG PET/computed tomography (CT) exams at our institution from June 2003 to June 2006 were included. Selected patients were followed and clinical information was reviewed retrospectively. Results from FDG PET-PET/CT, as blindly reviewed by a consensus of two experienced readers, were compared with the status of the disease as determined by other laboratory, clinical and imaging exams and clinical follow-up. FDG PET-PET/CT results were classified as true positive or negative and false positive or negative. The degree of FDG uptake in the positive lesions was semiquantified as maximum standard uptake value (SUVmax).

RESULTS

Fifty-seven FDG PET-PET/CT exams were done in 15 patients. Seven exams were done for initial staging, 8 during and 14 after the completion of therapy, and 28 for disease surveillance. For nodal disease FDG PET-PET/CT was true positive in 8, true negative in 47 and false positive in 2 exams (sensitivity 100%, specificity 96%). For extranodal disease FDG PET-PET/CT was true positive in 6, true negative in 48 and false positive in 3 exams (sensitivity 100%, specificity 94%). The mean SUVmax for the positive nodal lesions was 15.7 (range 6.9-21.7, median 18.5) and for extranodal lesions was 14.2 (range 6.2-24.3, median 12.4).

CONCLUSIONS

FDG PET-PET/CT is sensitive for the detection of viable disease in Burkitt's lymphoma. Affected areas demonstrated high degree of uptake that was reversible upon successful implementation of treatment.

CT and 18F-FDG PET for noninvasive detection of splenic involvement in patients with malignant lymphoma

OBJECTIVE

The purpose of this study was to determine the sensitivity and specificity of (18)F-FDG PET, CT, and combined PET/CT in the detection of splenic involvement at initial staging of lymphoma.

MATERIALS AND METHODS

A retrospective longitudinal analysis was performed on the records of 111 patients with proven lymphoma who had undergone PET and CT before and after treatment. CT scans were evaluated independently by two radiologists, and PET scans by two nuclear medicine physicians. Abnormal CT findings were defined as low-attenuation nodules or a splenic index greater than 725 cm(3) (> 2 SDs above the mean in 100 controls). An abnormal PET finding was defined as splenic uptake greater than hepatic uptake. True splenic involvement was defined retrospectively on the basis of the treatment response assessed with criteria revised in the International Harmonization Project on lymphoma. Observer agreement and sensitivity and specificity values were calculated.

RESULTS

Observer agreement for CT splenic index and PET findings was good. For initial splenic staging, the sensitivity and specificity of CT, PET, and PET/CT were 91% and 96%, 75% and 99%, and 100% and 95%.

CONCLUSION

For initial staging of splenic involvement in malignant lymphoma, the sensitivity and specificity of PET/CT can reach 100% and 95%. The sensitivity of the combined approach is higher than that of either technique alone.