Role of 18F-FDG PET/CT in the Assessment of Extranodal Lesions in Patients with Lymphoma: An Observational Study

Background: The diagnosis and management of lymphoma require a 
combination of various investigations to accurately identify the subtype, stage, 
and prognosis of the cancer. One of the most crucial initial investigations for 
lymphoma is imaging studies such as computed tomography (CT) and positron 
emission tomography (PET) scans, which can help to identify the location, size, 
and extent of lymph node involvement, as well as detect any extranodal spread. 
Methods: This was an observational study that investigated the results and 
assessment of PETCT scans performed on lymphoma patients with initial extra-
nodal lymphoma or extranodal involvement of advanced nodal lymphomas. 
This study was conducted in Assiut University Hospital, the Nuclear Medicine 
Unit.
Results: A total of 112 patients were included in the analysis. Their median age 
was 40 (2-86) years and more than half of the participants (54.5%) were males. 
Primary extranodal disease was seen in 37.5% while secondary extranodal 
pattern was 62.5%. The site of the primary lesion was cervical lymph nodes in 
82 (52.6%), followed by mediastinal lymph nodes in 19 (12.2%) and the rarest 
sites of primary lymphoma lesions were at the orbit, nose, skin, and prostate. 
The McNemar test was found to have a significant difference in the probability 
of detecting lesions between CT and PET/CT in bone marrow (P = 0.000), lung 
nodules (P = 0.000), mediastinal (P = 0.01) and para-aortic nodes (P = 0.006). 
Conclusion: PET/CT is superior to CT in detecting extranodal disease in the 
abdomen, especially in the spleen and liver, and BM-based osseous infiltration. 
PET/CT scan showed higher sensitivity, specificity, and accuracy which led to 
alteration of disease staging with marked effects on the decision of treatment 
regimens.