18 F-fluorodeoxyglucose-positron emission tomography in evaluation of primary cutaneous lymphoma

F-18 FDG PET/CT in staging and response assessment of primary cutaneous diffuse large B-cell lymphoma (leg type)

Primary cutaneous Diffuse Large B-Cell Lymphoma-leg type (PCDLBCL-LT) is a rare subtype of cutaneous lymphomas, with high frequency of extra-cutaneous relapse and poor prognosis. We report a case of 70-year-old lady who was diagnosed with PCDLBCL-LT on biopsy and underwent a baseline F-18 FDG PET/CT, followed by interim and post-treatment PET/CTs. With this case report, we highlight the findings of F-18 FDG PET/CT in the staging of this cutaneous lymphoma, and also emphasize on its role in the response assessment.

Extensive Extranodal Cutaneous Lymphomatous Involvement in a Case of Adult T-Cell Lymphoma - Advantage of 18F Fluorodeoxyglucose Positron-emission Tomography-Computed Tomography over Computed Tomography

Diffuse extranodal cutaneous lymphomatous involvement is a unique presentation in a case of adult T-cell lymphoma. We present the case of a 26-year-old female who presented with erythematous rashes with subsequent evaluation with 18F fluorodeoxyglucose positron-emission tomography-computed tomography showing enlarged inguinal and axillary lymph nodes, and biopsy findings from the inguinal lymph nodes were suggestive of adult T-cell lymphoma.

Multimodality imaging and treatment strategy for malignant scalp neoplasms in adults

Malignant scalp masses deserve much attention as they have the potential to destroy local structures, recur and metastasize to distant organs. Moreover, malignant scalp lesions are known to be more aggressive in behavior than their counterparts elsewhere in the body. Multimodality imaging is essential in narrowing the differential diagnoses of scalp masses, as well as in differentiating benign from malignant masses. Furthermore, imaging is important in (1) evaluating the extent of tumor invasion in the scalp, (2) staging the disease, (3) guiding surgical biopsy and/or resection of the tumor, (4) preoperative planning and post-treatment surveillance of scalp tumors. An interdisciplinary treatment approach is crucial for the management of scalp malignancies given their complex and aggressive nature. This review seeks to describe the unique clinical and imaging characteristics of various types of malignant scalp masses, as well as to review their current treatment strategies.

The clinical value of imaging in primary cutaneous lymphomas: Role of high resolution ultrasound and PET-CT

BACKGROUND:

Primary cutaneous lymphoma is a rare extranodal non-Hodgkin's lymphoma confined to the skin. The data on the imaging findings of primary cutaneous lymphomas are largely lacking and the current diagnosis is based on clinical and histopathological examination. With the advances in dermatological ultrasound and molecular imaging, newer perspectives in the evaluation of cutaneous lymphomas are available.

OBJECTIVE:

To review and describe the imaging findings in patient's with the diagnosis of primary cutaneous lymphoma.

METHODS:

A multicentric, retrospective observational study was undertaken in four countries to review the high resolution ultrasonography (HRUS) and fluorine 18-fludeoxyglucose positron emission tomography-computed tomography (PET-CT) imaging findings.

RESULTS:

We had 41 patients, Female:Male 1:4.1; mean age, 57 years; range, 13-94 years. High resolution ultrasonography of the primary cutaneous lesions revealed thickening of the dermis in all the cases and the lesions were hypoechoic without any calcifications or central necrosis. The sonographic appearances of the lesions were categorised into focal infiltrative, nodular, pseudonodular, and diffusely infiltrative patterns. Nodular and pseudonodular lesions were predominant in B cell lymphomas, while diffusely infiltrative lesions were more common in T-cell lymphomas. On colour Doppler imaging, the lesions were hypervascular. Whole body ¹⁸F-fludeoxyglucose PET-CT imaging of the patients revealed increased uptake of the metabolite in the lesions.

CONCLUSION:

Sonographic patterns based on high resolution ultrasonography provide early clues to the non-invasive diagnosis of primary cutaneous lymphomas and PET-CT is the recommended modality of imaging for staging and follow-up.

ADVANCES IN KNOWLEDGE:

High resolution ultrasound with colour Doppler and PET-CT imaging are complimentary to the clinical diagnosis of primary cutaneous lymphomas.

FDG-Avid Keloid on PET/CT Imaging

Keloid is a benign fibroproliferative growths resulting from an overexuberant healing response. A 51-year-old man with a 20-year history of keloid formation presented with a 1-year history of unexplained progressive weakness of both lower limbs. He was clinically suspected of having paraneoplastic neurologic syndrome. FDG PET/CT was performed to exclude underlying malignancy. FDG PET/CT revealed a giant FDG-avid keloid in the anterior chest wall without any other abnormal FDG uptake in the body. We emphasize that a benign FDG-avid keloid should be considered in the differential diagnosis of FDG-avid cutaneous lesions on PET/CT.

Blastic Plasmacytoid Dendritic Cell Neoplasm Evaluated by FDG PET/CT

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare and aggressive hematological malignancy. A 34-year-old man with a biopsy-proven BPDCN underwent FDG PET/CT for staging. FDG PET/CT revealed multiple mild FDG-avid cutaneous lesions on the chest and back, involvement of left inguinal lymph node, and a markedly increased FDG-avid subcutaneous mass in the left lower leg.

Composite Cutaneous Lymphoma (Iatrogenic Immunodeficiency-Associated Lymphoproliferative Disorder) in a Patient with Rheumatoid Arthritis Treated with Methotrexate: Staging and Evaluation of Response to Therapy with 18F-FDG PET/CT

A 67 year old woman with a 10 year history of rheumatoid arthritis (RA) treated with methotrexate and prednisone, presented with a 2 year history of worsening multiple cutaneous plaques of variable appearance. Two distinct skin lesions were biopsied to reveal a composite cutaneous lymphoma, possibly caused by long term methotrexate therapy. An [18F] fluoro-2-deoxy-D-glucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) was performed to stage the malignancy, and was later repeated to evaluate response to chemotherapy, which guided subsequent management. We present the PET/CT imaging findings of this very rare iatrogenic (methotrexate induced) immunodeficiency-associated lymphoproliferative disorder.

Diagnostic value of 18F-FDG PET/CT for cutaneous extranodal natural killer/T-cell lymphoma, nasal type

OBJECTIVE

To evaluate the use of fluorine-18 fluorodeoxyglucose (F-FDG) PET/computed tomography (CT) in the diagnosis of cutaneous extranodal natural killer/T-cell lymphoma, nasal type (C-ENK/T-NT).

METHODS

A total of 39 patients with newly diagnosed C-ENK/T-NT were enrolled between May 2006 and November 2013. Anatomic regions (n=429; five cutaneous and six extracutaneous regions per patient) were assessed using an F-FDG PET/CT scan and conventional staging methods (CSMs). F-FDG PET/CT and CSMs were compared and evaluated for their ability to detect tumor lesions and their influence on the staging and treatment strategies. Biopsy and clinical follow-up were used as the gold standard for diagnosis.

RESULTS

In total, 139 lesions were detected by CSMs and F-FDG PET/CT, of which there were 50 cutaneous and 89 extracutaneous-positive regions. F-FDG PET/CT detected 48 cutaneous and 88 extracutaneous regions. CSMs, however, detected only 34 cutaneous lesions and 61 extracutaneous lesions that were positive for malignancy (cutaneous comparison of PET/CT vs. CSMs, P<0.001; extracutaneous comparison of PET/CT vs. CSMs, P<0.05). Using F-FDG PET/CT, 8 (42%) patients were in stage I-II and 31 patients (58%) were in stage III-IV. F-FDG PET/CT staging was consistent with the final stage determination in 94.9% (37/39) of patients, whereas CSMs staging was correct in final stage determination in 74.4% (29/39) of patients (P=0.025).

CONCLUSION

Our study showed that F-FDG PET/CT scanning is a valuable modality for the detection of cutaneous and extracutaneous lesions of C-ENK/T-NT. F-FDG PET/CT may therefore influence future staging and treatment strategies.

Zosteriform Secondary Cutaneous Diffuse Large B-Cell Lymphoma on FDG PET/CT

We present a case of a woman who had erythematous papules on the abdomen accompanied with numbness and local heat sensation. She had received chemotherapy for advanced follicular lymphoma. F-FDG PET/CT demonstrated band-like hypermetabolic lesions seemingly involving dermatomes of lower abdominal wall, which was confirmed as secondary cutaneous diffuse large B-cell lymphoma via skin biopsy.

The utility of positron emission tomography with and without computed tomography in patients with nonmelanoma skin cancer

Combined positron emission tomography (PET) and computed tomography (CT) scans are widely used in the staging and monitoring of most malignancies. The differential for PET-positive cutaneous lesions includes primary skin cancers, infections, cutaneous metastases from distant malignancies, and benign neoplasms. In dermatology, PET/CT scans have been most widely studied in patients with melanoma and Merkel cell carcinoma. The role of PET/CT scans in the management of other cutaneous malignancies is less clear, but it has shown great promise in the management of patients with squamous cell carcinoma and cutaneous lymphoma. This review seeks to address the usefulness of PET/CT scans in nonmelanoma skin cancer and to provide guidance regarding the management of patients with incidental PET-positive nodules. Currently, there is limited experience with PET/CT scans for staging and monitoring of non-head and neck metastatic basal cell and squamous cell carcinomas, and results show limited sensitivity and specificity. We also address the evidence for management of an incidental PET-positive cutaneous nodule and recommend obtaining a biopsy specimen in patients with a known noncutaneous malignancy, a history of primary skin cancer, or a high risk of either cutaneous or noncutaneous malignancy.

The role of fluorine-18 fluorodeoxyglucose positron emission tomography in patients with mycosis fungoides

Purpose:

The aim of the present study is to evaluate the possible role of fluorine-18 fluorodeoxyglucose positron emission tomography-computed tomography (¹⁸F-FDG PET-CT) in the management of mycosis fungoides (MF).

Materials and Methods:

Nineteen patients (mean age, 40.6 years; median age 41 years; 16 males and 3 females) with risk of secondary lymph node (LN) involvement (those with large cell transformation, tumors, erythroderma, or enlarged LNs on physical examination) were included in the study. All patients underwent PET-CT scan by injecting 0.06 mCi/kg of F18 FDG. The maximum standard uptake value (SUVmax) was recorded for each patient.

Results:

The ¹⁸F-FDG PET-CT was positive in 15 patients. PET-CT detected local cutaneous disease in 13 cases. The range of SUVmax is 2.8–14.1. Out of 19 patients, hypermetabolic adenopathy is found in 9 patients and visceral involvement in one.

Conclusions:

Although the study population is small our findings suggests that ¹⁸F-FDG PET-CT can detect cutaneous and extracutaneous lesions in MF and may guide biopsies especially in patients with risk of secondary LN involvement.

Mycosis fungoides: Positron emission tomography/computed tomography in staging and monitoring the effect of therapy

A 58-year-old woman, diagnosed as a case of mycosis fungoides (MF), underwent [18F]-fluoro-D-glucose positron emission tomography/computed tomography (FDG PET/CT) examination. The study revealed intense FDG uptake in a large ulceroproliferative right thigh lesion, indurated plaques in the chest wall and left thigh, along with multiple sites of cutaneous involvement, axillary and inguinal lymphadenopathy. The patient underwent chemotherapy with CHOP regimen, radiotherapy for the right thigh lesion, along with topical corticosteroids and emollients for the disseminated cutaneous involvement. Repeat [18F]-FDG PET/CT study performed a year later, showed near complete disease regression specifically of the ulceroproliferative lesion and indurated cutaneous plaques, no change in lymphadenopathy, and a subtle diffuse progression of the remaining cutaneous lesions. A multidisciplinary approach to the diagnosis, staging and treatment of MF has long been suggested for optimizing outcomes from management of patients with this disease. This case highlights the potential role of incorporating PET/CT as a single modality imaging technique in the staging and assessment of response to therapy.

Extensive invasive extramammary Paget disease evaluated by F-18 FDG PET/CT: a case report

Extramammary Paget disease (EMPD) is a rare cutaneous, intraepithelial adenocarcinoma. Because of its rarity, little is known about the value of fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) in evaluating this disease. Our case report aims to increase current knowledge of FDG PET/CT in EMPD as a noninvasive imaging tool for assessing the extension of the disease and detecting distant metastases.We reported a 64-year-old Chinese man who presented with a slowly progressive, ill-margined erythematous lesion with a crusted, eroded, and scaly surface involving multiple sites of penis, scrotum, left pelvic wall, hip, groin, and thigh for >4 years, which became extensive in the past 1 year. He was referred for an FDG PET/CT examination to further evaluate the lesions. A following skin biopsy was performed to obtain a definitive histological diagnosis.FDG PET/CT imaging revealed mild FDG uptake at the extensive cutaneous lesion with subcutaneous invasion, involvement of lymph nodes, and multiple intense FDG-avid of skeletal metastases. According to the appearance of FDG PET/CT, a provisional diagnosis of advanced cutaneous malignancy was made. Histopathology findings indicated characteristic of EMPD. The patient was treated with radiation therapy and died from complications 2 months after the last dose of radiotherapy.Our case highlighted that a whole-body FDG PET/CT should be incorporated into the diagnostic algorithm of EMPD to give a comprehensive assessment of this disease.

Detection of recurrent cutaneous angiosarcoma of lower extremity with (18)f-fluorodeoxyglucose positron emission tomography-computed tomography: report of three cases

Cutaneous angiosarcomas (CAS) are uncommon, aggressive tumours. Very rarely, they arise from the lower extremity. Such tumours are usually associated with chronic lymphedema, a phenomenon known as Stewart-Treves Syndrome. Treatment is usually radical surgery with adjuvant therapy (radiotherapy/chemotherapy). Recurrence rate after primary treatment is high. Because of post therapy changes, conventional imaging has limited specificity for diagnosing recurrence. (18)F-Fluorodeoxyglucose ((18)F-FDG) positron emission tomography-computed tomography (PET-CT) might be useful in such patients. It can demonstrate local recurrence along with distant metastasis, if any and can have significant impact on patient management. We here present three cases of recurrent CAS of lower extremity diagnosed with (18)F-FDG PET-CT.

PET in T-Cell Lymphoma

Most non-Hodgkin lymphomas (NHL) are of B-cell origin; only about 10% are T-cell or NK-cell lymphomas. The clinical features of T/NK-cell lymphomas differ from those of B-cell lymphomas: advanced stage and extranodal disease are more common and the prognosis is worse. Several studies have confirmed that 2-[fluorine-18]fluoro-2-deoxy-D-glucose (18FDG) uptake varies among different subtypes of lymphoma, a disparity that can be explained by the differences in histology, proliferation of tumor cells, and the ratio of viable tumor and reactive cells in the environment. These observations are based on investigation of B-cell lymphomas. Positron emission tomography (PET)/computed tomography (CT) was found to be useful both at staging and at measuring the therapeutic outcome after two to three cycles of chemotherapy (interim PET/CT). Several meta-analyses have confirmed the role of PET in evaluating the viability of the residual tumor mass after treatment. 18FDG-PET has been proved to have an excellent negative predictive value. Conversely, only a few studies have investigated the role of FDG-PET in T/NK-cell lymphomas. This paper summarizes the current information regarding the potential use of PET/CT in patients with T-cell lymphoma.

[Malignant lymphoma of the skin: update on diagnostics and therapy of primary cutaneous B-cell lymphoma]

The diagnosis of primary cutaneous B-cell lymphoma is made based principally on the results of histological investigations and staging. For an exact staging abdominal sonography and chest X-ray examinations and for appropriate clinical symptoms special investigations as well as radiological imaging procedures including PET are indicated in addition to conventional laboratory investigations. For therapy rituximab is normally administered as monotherapy in order to avoid over therapy of indolent lymphoma. Further options are radiotherapy and new approaches with electrochemotherapy as well as pegylated doxorubicin.

Extranodal manifestations of lymphoma on [¹⁸F]FDG-PET/CT: a pictorial essay

Lymphoma is the seventh most common type of malignancy in both sexes. It is a neoplastic proliferation of lymphoid cells at various stages of differentiation and affects lymph nodes with infiltration into the bone marrow, spleen and thymus. However, extra nodal involvement is frequently seen in many cases. With the development of dedicated positron emission tomography (PET) scanners with fused computed tomographic (CT) systems in the same gantry, [18F]fluorodeoxyglucose (FDG)-PET/CT has become a major tool in the evaluation of lymphomas and it is inimitable in certain situations such as assessment of response to therapy. Extranodal lymphoma can present with diverse manifestations and sometimes mimics other organ-related pathologies. Knowledge of the protean manifestations of extranodal lymphoma is required to accurately detect the disease and differentiate it from the various physiologic and benign causes of FDG uptake in various organs. We present a case series of extranodal involvement of histologically proven cases of lymphomas detected on FDG-PET/CT at our institute to demonstrate the challenges in interpretation of extranodal lymphoma.

Non-Hodgkin's lymphoma of the bone and the liver without lymphadenopathy revealed on FDG-PET/CT

Primary extranodal lymphomas are much less frequent than nodal lymphomas. Osseous and hepatic lymphomas commonly present with additional nodal lesions. Primary lymphoma of the bone or of the liver without nodal disease is uncommon. We describe a case of extranodal non-Hodgkin's lymphoma with numerous osseous and hepatic lesions without any lymph node involvement on FDG-PET/CT images. This is the first report of the coexistence of both osseous and hepatic lymphoma in the same patient without any lymph node involvement.

Incidental finding of F-18 FDG skin uptake in a patient with psoriasis during the evaluation of a recurrent papillary thyroid carcinoma

We report the case of a patient, referred in our institution for a PET/CT for a suspected recurrence of papillary thyroid carcinoma. An intense cutaneous uptake of FDG was seen in the upper neck region. The clinical examination showed an indurate and thickened red descamative plaque evocative of psoriasis, and the patient reported a long history of psoriatic lesions of the skin, evolving for many years. This case illustrates an incidental finding which must be recognized, and not confounded with other causes of skin uptake. The FDG image is not surprising, as FDG uptake is expected in active inflammatory disease.

Characterization of T-cell lymphomas by FDG PET/CT

OBJECTIVE

The purpose of this article is to describe the utility of FDG PET/CT in documenting sites of disease in patients with T-cell lymphomas, to quantify the degree of FDG avidity in the various subtypes of this heterogeneous group of disorders, and to highlight the pattern of imaging findings associated with specific disease subtypes.

MATERIALS AND METHODS

A retrospective review of patients with T-cell lymphomas who underwent PET/CT examination for initial disease staging or at disease relapse over a 5-year period was undertaken by correlation between a patient database and a PACS radiology information system. Disease subtypes were grouped according to World Health Organization categorization of mature natural killer cell-T-cell neoplasms. Sites of disease involvement were documented according to cutaneous or extranodal, nodal, and visceral locations. The maximum standardized uptake value (SUV) was recorded for each patient.

RESULTS

One hundred thirty-five patients with T-cell lymphoma were included, and sites of disease were documented by use of FDG PET/CT in 122 (90%) patients. Of those 122 patients, 55 (45%) had cutaneous involvement, 95 (78%) had FDG-avid lymphadenopathy, and 54 (44%) had FDG-avid extranodal disease other than cutaneous involvement. A significant difference in maximum SUV was observed in cases of mycosis fungoides and mycosis fungoides with large cell transformation (SUV, 11.3 vs 3.8; p < 0.05).

CONCLUSION

We found high rates of FDG positivity in T-cell lymphoma. Given the propensity for disease involvement outside the normal scan range of diagnostic CT, we recommend that patients with T-cell lymphoma be scanned from vertex to feet by use of PET/CT.

Importância da cintilografia com gálio-67 no linfoma cutâneo primário de células B: relato de dois casos

Os autores relatam dois casos de linfoma cutâneo de células B, nos quais o correto estadiamento, tratamento e seguimento foram possíveis graças à combinação de exames convencionais e a cintilografia com gálio-67.

FDG PET/CT of extranodal involvement in non-Hodgkin lymphoma and Hodgkin disease

The term extranodal disease refers to lymphomatous infiltration of anatomic sites other than the lymph nodes. Almost any organ can be affected by lymphoma, with the most common extranodal sites of involvement being the stomach, spleen, Waldeyer ring, central nervous system, lung, bone, and skin. The prevalence of extranodal involvement in non-Hodgkin lymphoma and Hodgkin disease has increased in the past decade. The imaging characteristics of extranodal involvement can be subtle or absent at conventional computed tomography (CT). Imaging of tumor metabolism with 2-[fluorine-18]fluoro-2-deoxy-d-glucose (FDG) positron emission tomography (PET) has facilitated the identification of affected extranodal sites, even when CT has demonstrated no lesions. More recently, hybrid PET/CT has become the standard imaging modality for initial staging, follow-up, and treatment response assessment in patients with lymphoma and has proved superior to CT in these settings. Certain PET/CT patterns are suggestive of extranodal disease and can help differentiate tumor from normal physiologic FDG activity, particularly in the mucosal tissues, bone marrow, and organs of the gastrointestinal tract. Familiarity with the different extranodal manifestations in various locations is critical for correct image interpretation. In addition, a knowledge of the differences in FDG avidity among the histologic subtypes of lymphoma, appropriate timing of scanning after therapeutic interventions, and use of techniques to prevent brown fat uptake are essential for providing the oncologist with accurate information.

Cutaneous and subcutaneous imaging on FDG-PET: benign and malignant findings

F-18 fluorodeoxyglucose positron emission tomography (F-18 FDG PET) has been shown to be useful in the evaluation of many tumors due to its high sensitivity and specificity. However, false-positive interpretations may occur from benign subcutaneous and cutaneous etiologies. At our institution we have encountered FDG-PET scans which demonstrated a variety of cutaneous and subcutaneous lesions including stomas, hernias, rhinophyma, dose infiltrations, physiologic muscle uptake, and tophaceous gout. Additionally, malignant cutaneous and subcutaneous malignant lesions may also demonstrate substantial F-18 FDG uptake on PET scans, including lymphoma, skin metastases, and melanoma. The purpose of this atlas article is to demonstrate and review key features of various cutaneous and subcutaneous lesions, both benign and malignant, which can result in hypermetabolism on FDG-PET or PET-CT scans.

(18)F-FDG avidity in lymphoma readdressed: a study of 766 patients

PET/CT with (18)F-FDG is an important noninvasive diagnostic tool for management of patients with lymphoma, and its use may surpass current guideline recommendations. The aim of the present study is to enlarge the growing body of evidence concerning (18)F-FDG avidity of lymphoma to provide a basis for future guidelines.

METHODS

The reports from (18)F-FDG PET/CT studies performed in a single center for staging of 1,093 patients with newly diagnosed Hodgkin disease and non-Hodgkin lymphoma between 2001 and 2008 were reviewed for the presence of (18)F-FDG avidity. Of these patients, 766 patients with a histopathologic diagnosis verified according to the World Health Organization classification were included in the final analysis. (18)F-FDG avidity was defined as the presence of at least 1 focus of (18)F-FDG uptake reported as a disease site. Nonavidity was defined as disease proven by clinical examination, conventional imaging modalities, and histopathology with no (18)F-FDG uptake in any of the involved sites.

RESULTS

At least one (18)F-FDG-avid lymphoma site was reported for 718 patient studies (94%). Forty-eight patients (6%) had lymphoma not avid for (18)F-FDG. (18)F-FDG avidity was found in all patients (100%) with Hodgkin disease (n = 233), Burkitt lymphoma (n = 18), mantle cell lymphoma (n = 14), nodal marginal zone lymphoma (n = 8), and lymphoblastic lymphoma (n = 6). An (18)F-FDG avidity of 97% was found in patients with diffuse large B-cell lymphoma (216/222), 95% for follicular lymphoma (133/140), 85% for T-cell lymphoma (34/40), 83% for small lymphocytic lymphoma (24/29), and 55% for extranodal marginal zone lymphoma (29/53).

CONCLUSION

The present study indicated that with the exception of extranodal marginal zone lymphoma and small lymphocytic lymphoma, most lymphoma subtypes have high (18)F-FDG avidity. The cumulating evidence consistently showing high (18)F-FDG avidity in the potentially curable Burkitt, natural killer/T-cell, and anaplastic large T-cell lymphoma subtypes justifies further investigations of the utility of (18)F-FDG PET in these diseases at presentation.

CT and PET/CT findings of T-cell lymphoma

OBJECTIVE

The purpose of this study was to describe the extranodal features of T-cell lymphoma at CT and PET/CT.

CONCLUSION

The extranodal features of T-cell lymphoma are not specific and usually cannot be used to differentiate T-cell lymphoma from other aggressive types of lymphoma. Noncutaneous subtypes frequently manifest with visceral involvement. The goal of CT in initial staging is to exclude visceral involvement. Evidence on the utility of PET/CT is promising, showing high diagnostic value in evaluation of occult disease and treatment response, but the role of PET/CT is evolving.

F-18-fluoro-deoxy-glucose positron emission tomography in the assessment of peripheral T-cell lymphomas

F-18-fluoro-deoxy-glucose positron emission tomography (PET) is highly sensitive and specific in the imaging of B-cell lymphomas. In contrast, its utility in the diagnostic evaluation of T-cell lymphomas is less defined. In this article, we present our finding utilizing PET in peripheral T-cell lymphomas (PTCL). A retrospective review of patients who underwent PET examinations at our institution produced 24 PET examinations among patients with PTCL. A lesion-based analysis was undertaken to evaluate the diagnostic accuracy of PET in PTCL. PET findings were compared with a standard of reference and sensitivity, specificity, positive and negative predictive values were calculated. PET had an overall sensitivity of 86% and specificity of 100%. PET had high sensitivity (95%) at nodal and non-cutaneous extra-nodal sites and poor sensitivity (13%) at cutaneous sites. The mean SUV of abnormal foci in anaplastic large cell lymphoma was 11 mg/ml (range: 3 - 40), and PTCL-unclassified was 8 mg/ml (range: 1 - 23).

Nodal status of malignant lymphoma in pelvic and retroperitoneal lymphatic pathways: PET/CT

Nodal involvement of abdominal lymphatic pathways occurs in a number of histologic subtypes of malignant lymphoma. The histologic diagnosis of abnormal uptake in abdominal lymphatic pathways includes mainly non-Hodgkin lymphoma with B-cell lineage and Hodgkin lymphoma. Initial involvement of pelvic and retroperitoneal lymphatic pathways can result from a variety of underlying non-Hodgkin's lymphoma: follicular lymphoma, diffuse large B-cell lymphoma, marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) type, and mantle cell lymphoma. The diagnosis of these clinical entities requires various imaging techniques, including fluorine-18-fluorodeoxyglucose ((18)FDG) positron emission tomography/computed tomography (PET/CT), computed tomography, (67)Gallium scintigraphy, and magnetic resonance imaging (MRI). Specific symptoms of these diseases are often lacking, but intense (18)FDG accumulation on PET/CT may be a marker of disease activity. Interpretation of the presence of and the specific pattern of (18)FDG uptake may obviate the need for invasive biopsy. However, distinction of abnormal uptake is often difficult to determine because focal accumulation of (18)FDG in the urinary tract or intestine mimics nodal involvement in the pelvic and retroperitoneal lymphatic pathways. In this review, specific conditions causing nodal involvement of pelvic and retroperitoneal lymphatic pathways in patients with malignant lymphoma that may impact diagnostic and treatment decisions are highlighted.

Positron emission tomography in subcutaneous panniculitis-like T-cell lymphoma

Subcutaneous panniculitis-like T-cell lymphoma (SPTCL), an uncommon disorder, was diagnosed in a 17-year-old female when she presented with multiple hard subcutaneous masses that developed over 3 years. She was treated on chemotherapy consisting of cyclophosphamide, doxorubicin, vincristine, and prednisone. Pre- and post-treatment positron emission tomography study demonstrated dramatic resolution of the subcutaneous lesions indicating its usefulness in SPTCL staging and treatment response monitoring.

Nodal status of malignant lymphoma in pelvic and retroperitoneal lymphatic pathways: Comparison of integrated PET/CT with or without contrast enhancement

AIM

To determine the diagnostic accuracy of integrated contrast-enhanced positron emission tomography (PET) and computed tomography (CT), as compared with non-contrasted PET/CT, in evaluating nodal status of malignant lymphoma in pelvic and retroperitoneal lymphatic pathways.

MATERIALS AND METHODS

Sixty-six patients (33 men and 33 women) with malignant lymphoma underwent staging with integrated CT and fluorine-18-fluorodeoxyglucose ((18)FDG) PET. Tumor types were diffuse large B-cell lymphoma (n=26, 39%), follicular lymphoma (n=20, 30%), Hodgkin disease (n=16, 24%), and marginal zone B-cell lymphoma (n=4, 6%). Both non-contrasted PET/CT and contrast-enhanced PET/CT images were examined separately by two different qualified physicians for each imaging modality, and nodal status of pelvic and retroperitoneal lymphatic pathways was evaluated. Reference standard included follow-up with clinical, laboratory, and conventional CT findings. We compared diagnostic accuracy retrospectively on basis of per-patient and per-lesion analyses between two modalities using McNemar test, respectively.

RESULTS

Nodal status of pelvic and retroperitoneal lymphatic pathways was more accurately determined on contrast-enhanced PET/CT (n=52, 79%) compared with non-contrasted PET/CT (n=47, 71%). Difference in the accuracy of nodal staging between non-contrasted PET/CT and contrast-enhanced PET/CT was significant (p=0.048). On basis of per-lesion analysis, contrast-enhanced PET/CT determined more accurately the status of external iliac lymph node (p=0.002), internal iliac lymph node (p<0.0001), and common iliac lymph node (p=0.002) compared with non-contrasted PET/CT. Diagnostic accuracies of paraaortic lymph node, aortocaval lymph node, and paracaval lymph node were similar by either non-contrasted PET/CT or contrast-enhanced PET/CT.

CONCLUSION

Integrated contrast-enhanced PET/CT improves the diagnostic accuracy in evaluating nodal status of pelvic and retroperitoneal lymphatic pathways in patients with malignant lymphoma.

FDG-PET in T-cell and NK-cell neoplasms

BACKGROUND

A growing number of studies demonstrate the utility of (18)fluoro-2-deoxyglucose positron emission tomography (FDG-PET) in the management of malignant lymphoma. The results of FDG-PET, however, have not been studied extensively for T-cell and natural killer (NK)-cell neoplasms.

PATIENTS AND METHODS

We retrospectively evaluated pretreatment FDG-PET scans in 41 patients with T/NK-cell neoplasms diagnosed according to the World Health Organization (WHO) classification. Histological subtypes frequently included were peripheral T-cell lymphoma, unspecified (PTCLu, n = 11), extranodal NK/T-cell lymphoma, nasal type (ENKL, n = 8), primary cutaneous anaplastic large cell lymphoma (C-ALCL, n = 5), and angioimmunoblastic T-cell lymphoma (AILT, n = 4).

RESULTS

FDG-PET detected a lymphoma lesion in at least one site in 36 out of 41 patients. The positive rate was equally high in most histological subtypes except for cutaneous lymphomas: PTCLu 91%, ENKL 100%, C-ALCL 60%, AILT 100%. All the patients without an FDG-avid lesion had lesions restricted to skin. Among patients who had cutaneous lesions, only 50% had FDG-avid cutaneous lesions, all of which were tumorous. The positive rate of FDG-PET for bone marrow involvement was only 20%.

CONCLUSION

T/NK-cell neoplasms incorporated in this study were generally FDG-avid except for cutaneous lesions and bone marrow involvement.