Dados do Trabalho

Título

Brain Metabolism Redistribution from Neocortex to Primitive Brain Structures in a patient with Hodgkin’s Lymphoma.

Introdução/Justificativa

We have recently demonstrated a 18F-FDG PET/CT image pattern of brain metabolic redistribution from the neocortex to evolutionary ancient brain structures during the acute phase of COVID-19 respiratory syndrome (1). We report here a patient with extensive lesions caused by Hodgkin's lymphoma whose PET/CT demonstrated changes in the cerebral distribution of FDG, with reduced uptake in the neocortex and a relative increase in the basal ganglia, similar to that observed in acute COVID-19 (1).

Relato

A 57-year-old female patient with a history of hypertension and hypothyroidism, presented with weight loss and generalized lymphadenopathy. Biopsy revealed nodular sclerosis classical Hodgkin's lymphoma subtype. 18F-FDG PET/CT was requested for staging. The images showed marked hypermetabolism in lymphadenopathy below and above the diaphragm, spleen, and bone marrow, consistent with lymphoma infiltration.
Reduced radiotracer uptake was also observed in the cerebral neocortex and relatively increased uptake in the basal ganglia. Semiquantitative analysis of FDG uptake in multiple brain regions was conducted using dedicated software, and the standard deviation (SD) of brain uptake in each region was calculated compared to a normal database, using the whole brain as the reference region for normalization. Quantification revealed marked increased relative uptake in lenticular nuclei (13.7 SD), thalamus (4.6) and brainstem (3.7), and reduced uptake in the frontal, parietal, and temporal lobes (-3,9 to -0,1 SD). Before starting chemotherapy, the patient experienced weakness, multiple episodes of diarrhea, and decreased level of consciousness. She developed hemophagocytic syndrome, septic shock, and died 19 days after PET/CT.


Aggressive lymphomas exhibit intense FDG uptake, often with a high tumor burden. This can elevate blood lactate levels, which would become an alternative energy substrate for the brain and, by competition, reduce FDG uptake, as suggested by Yi HK et al (2). This is also described in individuals engaged in intense exercise, where decreased FDG uptake may be attributed to potential lactate utilization by the brain (3). The relatively preserved FDG uptake in the basal ganglia could be viewed as a physiological protective mechanism in response to reduced glucose availability for the brain. The oldest parts of the brain are vital for survival and must be preserved to maintain essential life functions. Despite being an organ with one of the highest glucose demands, the brain lacks the ability to store metabolic products for later use. Therefore, during competition with neoplastic cells for the available energy substrate, metabolic redistribution could contribute to preserving essential brain functions.

Conclusão

Patients with high tumor burden due to Hodgkin's lymphoma may exhibit not only a global reduction in cerebral glucose uptake but also a redistribution of glucose consumption from the neocortex to older brain structures which are essential for survival.

Palavras Chave

HIPOMETABOLISM; BRAIN; 18F-FDG PET/CT; Lymphoma