PET/CT imaging in management of concomitant Hodgkin lymphoma and tuberculosis – a problem solver tool

Key Clinical Message Infectious lymph nodes mimicking lymphoma is challenging for accurate staging. Although 18F‐FDG is a nonspecific tracer accumulating not only in tumor cells but also in inflammatory tissues, the metabolic features and uptake kinetics give valuable information: 18F‐FDG PET/CT appears as a useful problem solver tool in ambiguous situation.


Introduction
Initial accurate staging is crucial for optimal lymphoma treatment planning [1]. Overlap of different diseases can be complex for management, in particular overlap of conditions involving lymph nodes extension.

Case Report
We report the case of a 28-year-old man, with no previous history, addressed for the management of suspect Hodgkin lymphoma. He presented with an isolated progressively growing cervical tumefaction, ECOG1, and no night sweats. Cervical lymph node biopsy revealed Hodgkin scleronodular lymphoma with Hodgkin Reed Sternberg cells, CD30 and CD15 positive. Thorax X-ray and CT scan revealed an alveolo-interstitial syndrome, suspected to be tuberculosis. Bronchoscopy was noncontributive but bronchoalveolar lavage became positive for mycobacterium tuberculosis.
18 F-FDG PET/CT scan was performed for initial staging of his lymphoma confirming intense hypermetabolic cervical lymph node involvement. There was an increased uptake of the alveolo-interstitial syndrome associated with loco-regional mediastinal lymph nodes. In addition, PET depicted an incidental digestive colon intense uptake, with below diaphragm lymph nodes. Colonic biopsy was therefore performed, revealing digestive colon tuberculosis localization. Staging was thus equivocal on account of the overlap of both tuberculosis (TB) and Hodgkin lymphoma (HL): stage II HL with only above diaphragm lymph nodes, associated with pulmonary and colic tuberculosis with loco-regional TB lymph nodes, or stage III HL with above and below diaphragm lymph nodes, associated with pulmonary and colic tuberculosis. Case was discussed among multidisciplinary staff. Due to hemorrhage risk, biopsy of pericolonic lymph nodes was not achievable and empiric quadruple drug regimen therapy for tuberculosis was first initiated (isoniazid, rifampin, pyrazinamide, and ethambutol) while HL treatment is pending. As to solve the Hodgkin lymphoma staging issue, an early PET/CT evaluation was performed after 1-month antituberculosis therapy. PET/CT showed partial metabolic response of pulmonary and colic tuberculosis localization and complete metabolic response of pericolonic below diaphragm lymph nodes, in favor of their tuberculosis origin. Patient was therefore staged IIAa for Hodgkin disease, unfavorable group (>4 lymph nodes groups), and specific treatment was initiated consisting of chemotherapy with ABVD (doxorubicin-bleomycinvinblastine-dacarbazine) and radiation therapy (30 Gy). Final PET/CT assessment after 4 ABVD showed complete metabolic response of lymphoma (Deauville 2 criteria) [2,3] and complete disappearance of tuberculosis (Fig. 1). Accurate staging allowed avoiding overtreatment with BEACOPP and the known infectious risks especially with the indication of TB, and this early stage of disease benefited from complementary radiotherapy planning [4].

Discussion
Imaging with 18 F-FDG PET/CT is known to be the gold standard imaging for management, staging, restaging, assessment, and follow-up of HL [1][2][3][4][5][6]. However, it is well known that 18 F-FDG PET/CT is a nonspecific tracer that can accumulate not only in tumor cells but also in macrophages, granulation, and inflammatory tissues. It allows assessment of both tumoral metabolism and inflammatory process. Tuberculosis extension often affects lymph nodes; hence, both TB and HL present with intense accumulation of FDG in the PET/CT imaging [7], and the measurement of SUVmax is inadequate to differentiate them (Fig. 2). As a consequence, TB lymph nodes mimicking HL make accurate HL stating difficult. Cases of TB mimicking lymphoma on 18 F-FDG PET/CT evaluation have been described [8,9]. Our case points out the complex intricacy of both TB and HL. Biopsy and pathology of all sites are not achievable, and metabolic features give valuable information in those situations.
Overlap of different conditions involving lymph nodes extension is challenging for accurate lymphoma staging.
18 F-FDG PET/CT appears to be a useful tool as problem solver in ambiguous situation: (1) guiding biopsyas performed in our case with the colon pathological uptake proven to be tuberculosis; (2) allowing early