F-18 FDG Uptake in Subcutaneous Panniculitis-Like T-Cell Lymphoma

Inverted FDG Uptake Pattern in Subcutaneous Panniculitis-Like T-Cell Lymphoma

ABSTRACT

A 47-year-old woman presented with a 2-month history of subcutaneous nodules, erythema, and fever. 18F-FDG PET images demonstrated inverted FDG uptake pattern corresponding to the subcutaneous lesion against lymph nodes. The specimen of the inguinal lesion showed massive infiltration of small lymphocytes in the adipose tissue with rimming adipocytes, whereas very few tumor cells infiltrated the lymph nodes. Subcutaneous panniculitis-like T-cell lymphoma (SPTCL) was diagnosed. SPTCL normally shows quite interesting distribution of tumor cells, that is, lymph node involvement is usually absent. Therefore, this case highlighted the importance of the inverted accumulation pattern on FDG PET to suspect SPTCL.

18F-FDG PET/CT-Guided Diagnosis and Evaluation of Treatment Response to Cyclosporine A in Maldistributed Subcutaneous Panniculitis-like T-Cell Lymphoma Without Typical Skin Rash

A 30-year-old woman presented with persistent fever and elevated lactate dehydrogenase levels without skin rash. F-FDG PET/CT revealed FDG uptake in subcutaneous tissues in the forearm, buttocks, and lower limbs, whereas the trunk was unaffected. She was diagnosed with subcutaneous panniculitis-like T-cell lymphoma based on a PET/CT-guided subcutaneous tissue biopsy from the thigh. Although conventional cytotoxic agent-based chemotherapies failed to achieve disease remission, subsequent cyclosporine A treatment promptly resolved the fever and laboratory abnormalities. Remarkably, abnormal FDG uptake disappeared entirely on follow-up PET/CT, demonstrating its utility in the evaluations of responses to emerging cyclosporine A-based treatments in subcutaneous panniculitis-like T-cell lymphoma.

Musculoskeletal Pitfalls on Fluorodeoxyglucose F 18 PET-Computed Tomography: Pictorial Review

A wide range of musculoskeletal processes can demonstrate increased uptake on PET-computed tomography (CT) with fluorodeoxyglucose (FDG) F 18, including reactive, benign neoplastic, inflammatory, traumatic, posttreatment, and arthritic conditions that may mimic malignancy. In addition, physiologic causes of increased FDG uptake such as asymmetric muscle use and presence of brown fat can lead to increased FDG uptake and potential false-positive results. This article presents various case examples of non-malignant musculoskeletal hypermetabolism on 18F-FDG PET-CT and describes useful tools to avoid the potential pitfall of misinterpreting these as malignancy.

Subcutaneous Panniculitis-like T Cell Lymphoma Mimicking Early-Onset Nodular Panniculitis

Patient: Male, 24

Final Diagnosis: Subcutaneous panniculitis-like T-cell lymphoma

Symptoms: Fever • skin nodules

Medication: —

Clinical Procedure: Skin biopsy • PET-CT

Specialty: Hematology

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.

Positron emission tomography revealed diffuse involvement of the lower legs and occult extracutaneous lesions in subcutaneous panniculitis-like T-cell lymphoma

Subcutaneous panniculitis-like T-cell lymphoma (SPTCL) is a very rare type of cutaneous lymphoma that localizes primarily in the subcutaneous adipose tissue without palpable involvement of the lymph nodes. Most often, it presents as multiple, painless, subcutaneous nodules on the extremities and trunk. In this study, we describe an unusual case of SPTCL that mimicked phlegmonous inflammation; PET/CT revealed massive diffuse involvement of the lower legs, low-grade nodal active disease, and occult involvement of the intra-abdominal visceral fat. A repeat PET/CT study after CHOP chemotherapy revealed complete resolution of abnormal FDG uptake in the initially involved sites.

Usefulness of F-18 FDG PET/CT in subcutaneous panniculitis-like T cell lymphoma: disease extent and treatment response evaluation

BACKGROUND.: Subcutaneous panniculitis-like T-cell lymphoma (SPTCL) is a rare form of cutaneous lymphomas, accounting for less than 1% of cases of non-Hodgkin's lymphoma. Fluorine-18 fluorodeoxyglucose (F-18 FDG) positron-emission tomography/computed tomography (PET/CT) findings of SPTCL before and after treatment were rarely reported. CASE REPORT.: We report a case of SPTCL in which F-18 FDG PET/CT showed increased FDG accumulations in numerous subcutaneous nodules without extracutaneous disease. Contrast-enhanced CT during F-18 FDG PET/CT showed multiple minimally enhancing nodules with an infiltrative pattern in the subcutaneous layer throughout the body. Follow-up F-18 FDG PET/CT after three cycles of CHOP chemotherapy showed a complete metabolic remission of the lesions. CONCLUSIONS.: F-18 FDG PET/CT is suggested to be useful in assessing the disease activity, extent and treatment response in SPTCL.

Radiological and clinical features of subcutaneous panniculitis-like T-cell lymphoma

OBJECTIVE

To retrospectively analyze computed tomography (CT) and clinical findings of patients with subcutaneous panniculitis-like T-cell lymphoma (SPTCL).

MATERIALS AND METHODS

The CT findings were retrospectively assessed in 8 patients (6 men, 2 women; age range, 23-60 years; mean age, 39.8 years) with pathologically proven SPTCL. The tumor location, number, distribution, size, and morphological characteristics on CT were evaluated, as were maximum standardized uptake values on positron emission tomography. We also evaluated patient symptoms, laboratory findings, immunophenotype, involvement of bone marrow, treatment, and outcomes.

RESULTS

All 8 patients had multiple (range, 4 to numerous) soft tissue lesions involving subcutaneous fat tissue of the chest, abdominal wall, back, and buttock. Lesions varied in size (range, 0.5-10 cm) and showed reticular (n = 1), nodular (n = 4), and diffuse infiltrative (n = 3) patterns. Three patients had lesions involving the entire thickness of fat tissue, 3 had partial lesions, and 2 had variable lesions. Skin thickening was mild in 4 patients, moderate in 2, and severe in 2; fascia thickening was mild in 3 patients, moderate in one, severe in one, and variable in 2. In 7 patients, lesions were accompanied by engorged supplying vessels. At onset, maximum standardized uptake values varied from 1.2 to 4.7, decreasing to 0.0 to 4.2. Five patients had αβ type and one had γδ type. Clinical outcome varied: two remain alive with disease, two had no disease, and one died.

CONCLUSIONS

The SPTCL is characterized by multiple, nodular, or diffuse soft tissue lesions involving subcutaneous fat tissue, accompanied by engorged vessels and skin and fascial thickening. Patients vary in presentation and in treatment outcomes.

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.

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.