Differentiating Hodgkin Lymphoma and Sarcoid Reaction in Subsequent FDG-PET/CT: A Case Report and Literature Review

Abstract

Sarcoidosis is frequently associated with various hematological and solid tumors; it can be discovered by chance during tumor evaluations. Sarcoidosis can occur before some cancers, coexist with others, or be diagnosed 1 to 2 years later. Sarcoid reaction affecting hilar and mediastinal lymph nodes can pose a diagnostic challenge in patients with histopathological confirmation of Hodgkin lymphoma who are being evaluated using fluorodeoxyglucose-positron emission tomography computed tomography (FDG-PET/CT) scan because it cannot be easily distinguished from lymphoma infiltration. The presence of an increase or persistence of a prominent activity on a follow-up FDG-PET/CT scan after chemotherapy treatment for lymphoma that is associated with a complete metabolic response in the site of the primarily diagnosed lymphomatous disease is highly suggestive of concurrent sarcoidosis and necessitates careful assessment to avoid unnecessary therapy.

Keywords: FDG-PET/CT; Hodgkin lymphoma; diagnostic challenge; sarcoid reaction; sarcoidosis.

Fig. 1

A 17-year-old male patient diagnosed with Hodgkin lymphoma. ( A ) Cross-sectional computed tomography (CT) slice showing an abnormally enlarged left cervical lymph node level Va ( blue arrow ). ( B ) Cross-sectional CT slice showing an abnormally enlarged left supraclavicular matted lymph nodes ( blue arrow ). ( C , D ) Cross-sectional CT slices showing bilateral hilar and mediastinal lymph nodes ( blue arrows ).

Fig. 2

A 17-year-old male patient diagnosed with Hodgkin lymphoma. ( A ) Imaging from staging fluorodeoxyglucose-positron emission tomography computed tomography ( ¹⁸ F-FDG-PET/CT) scan reveals hypermetabolic left cervical, left supraclavicular, and bilateral mediastinal lymph nodes (more so on the right side) with normal lung parenchyma bilaterally ( left image : anterior maximum intensity projection image from ¹⁸ F-FDG-PET; right images : axial fused PET/CT images). ( B ) Images from interim ¹⁸ F-FDG PET/CT scan demonstrating complete metabolic resolution of the hypermetabolic left cervical and left supraclavicular lymph nodes, with persistence of bilateral mediastinal and hilar lymph nodes with interval increase in number and note of diffuse bilateral supraclavicular brown fat FDG uptake along with interval development of mildly hypermetabolic right upper lobe pulmonary ground glass opacity ( right image : anterior maximum intensity projection image from ¹⁸ F-FDG-PET; left images: axial fused PET/CT images).