Paediatric and adolescent Hodgkin lymphoma: information derived from diffuse organ uptake of 18 F-fluorodeoxyglucose on pre-treatment and on interim PET/CT

Physiological distribution of 18F-FDG in the spinal cord: A systematic review

Context: The importance of physiologic distribution of ¹⁸F-FDG in the spinal cord.Objective: The recognition of the physiologic distribution of ¹⁸F-FDG in the spinal cord is pivotal for accurate PET/CT imaging interpretation, especially in oncologic patients. Therefore, we performed a systematic review to investigate the normal distribution of ¹⁸F-FDG throughout the spinal cord.Methods: Data sources: We carried out a comprehensive search of the literature on the physiologic patterns of ¹⁸F-FDG distribution in the spinal cord. PubMed and Scopus databases were searched using the following keywords: "spinal cord" AND "FDG". Data extraction: Findings of the selected articles were described.Results: Thirteen studies comprising 24,125 patients entered the systematic review. These investigations showed discrepancies in location, size, number, and intensity of ¹⁸F-FDG uptake throughout the spinal cord. However, cumulative results showed that ¹⁸F-FDG uptake was higher in the lower thoracic portion of spinal cord (T11-T12). Moreover, a decreasing trend in ¹⁸F-FDG uptake was observed from cervical to lumbar levels. Low maximal standardized uptake values, female sex, and higher body weight seem to be related to the physiological spinal cord ¹⁸F-FDG uptake.Conclusions: On ¹⁸F-FDG PET/CT imaging, focal hypermetabolism of the spinal cord at the level of lower thoracic and lower cervical vertebrae should be considered physiological until proven otherwise.

Determinants of activity of brown adipose tissue in lymphoma patients

The determinants of brown adipose tissue (BAT) activity are not yet known in detail but might serve as future therapeutic targets against obesity and the metabolic syndrome. We analyzed 235 datasets of lymphoma patients with two PET/CT examinations at different time points retrospectively. We assessed the anthropometric characteristics, features related to the metabolic syndrome, thyroid dysfunction, season of the PET/CT examination, weight change, prior cancer history, lymphoma subgroups, disease activity, and specific lymphoma-related therapies, and evaluated their association with BAT activity. We found BAT activity in 12% of all examinations, and the incidence of BAT activity after initially negative examinations was 10%. In multivariate regression analysis, the prevalence of BAT activity was associated with age, body mass index, sex, the season of the examination, diabetes mellitus, arterial hypertension, and medication on the beta-receptors. New BAT activity arose more often in patients without preceding lymphoma-related therapy. No specific medication was associated with BAT activity. In conclusion, this study confirms the potential connection of BAT with the metabolic syndrome. Preceding lymphoma-related therapy might have an inhibitory effect on the recruitment of BAT.

Importance of PET/CT examination in patients with malignant uveal melanoma

INTRODUCTION

Diagnostic and therapeutic management of the patient with malignant uveal melanoma (MMU) is subject to ongoing efforts to innovate. PET/CT (Positron Emission Tomography / Computed Tomography) examination is important in both diagnosis and metastases.

MATERIAL AND METHODS

Evaluation of the importance of PET/CT examination in the group of patients diagnosed with MMU in the period 12.1.2016 to 6.12.2018. All patients with a diagnosis of secondary retinal detachment, suspected uveal melanoma, underwent standard examinations to detect possible metastases (liver ultrasound, chest X-ray). Patients for whom a stereotactic radiosurgery solution was planned due to the stage of the disease this examination was to exclude metastasis in the liver or lungs. PET/CT examination is part of the protocol within the exclusion criteria for treatment with stereotactic radiosurgery in one day session surgery.

RESULTS

In the group of 84 patients, 47 women (56 %) and 37 men (44 %) were aged between 26 and 90 years. Their average age was 61.4 years. The median group was 64 years, modus 65 years. Of 84 patients, 79 (94 % of cases) had a diagnosis of C69.3 (choroidal melanoma) and 5 patients (6 % of cases) had a diagnosis of C69.4 (ciliary body melanoma). Subsequent PET/CT examination in many patients did not reveal hypermetabolic manifestations that could involve various pathological processes, in others the radiopharmaceutical was captured in the primary tumor area of the uveal tract. Hypermetabolism in eye globe was only found in melanomas with a volume of more than 0.5 cm3. PET/CT examinations were 85, with one patient undergoing examination twice. However, in 25 patients (26 examinations), the radiopharmaceutical was taken up in places that subsequently required closer attention. The initial aim of the examination was to locate possible metastases of MMU. In the others, 3 incidents have been reported: increased metabolism in the lung and liver, thyroid and mediastinal lymph nodes. Of the 85 examinations, 26 (30.6 %) resulted in a hypermetabolic manifestation of accumulation, which was not located in the eye tract, resp. right in the eye. Two malignancies (prostatic carcinoma and rectosigmal carcinoma) have occurred in two patients. Very important was the discovery of MMU metastasis in the liver, which confirmed the important role of PET/CT examination in the management of MMU patients. The metastasis was discovered after repeated PET/CT examination.

CONCLUSION

PET/CT examination is a technically demanding examination and is one of the possibilities of imaging intraocular melanoma in tumors with volume more than 0.5 cm3. It is important in determining the grading and staging of the disease before radiosurgical treatment and also in detecting possible metastases after MMU treatment in cases where ultrasound or MRI examinations do not give a definite result. However, our study confirmed the significance of this examination for randomly detected 2 duplex malignancies (2.4%) and 3 incidentalomas (3.6%) in patients whose ophthalmologist diagnosed uveal melanoma and sent patients for full-body PET/CT examination.

[Kikuchi-Fujimoto disease mimicking malignant lymphoma in adolescents]

Kikuchi-Fujimoto disease, also known as histiocytic necrotizing lymphadenitis, is a rare cause of lymphadenopathy in children. This benign disease can mimic lymphoma and misleads doctors. It was first described in Asia, where it occurred especially in young women. Recent publications show that it can also affect teenagers and young adults in Caucasian populations. The pathophysiology remains unknown. Three hypotheses have been raised for this disease: the role of viruses (in particular HHV-8), genetic predisposition (two alleles in HLA class II genes were found more frequently in patients with Kikuchi disease), and an autoimmune cause because of the correlation with lupus erythematosus. Few cases have been reported in Europe so far. In this article, we report three cases of Kikuchi disease observed in less than 2 months in a single hospital in France. All three patients were teenagers who presented with lymphadenopathy, either isolated or combined with fever, weakness, and weight loss. In all of them, the hypermetabolic activity of the lymph node on the PET scanner misled us to suspect lymphoma. The diagnosis of Kikuchi disease was finally made, for all patients, after 2 weeks in the hospital based on lymph node biopsy. Based on this report, we highlight that early biopsy in presence of lymphadenopathy can avoid unnecessary extensive investigations. Moreover, in this rare disease, it is very surprising to come across three cases that are not family-related, in such a short period of time. This strengthens the hypothesis of the possible implication of an environmental factor in the pathophysiology of Kikuchi disease.