Lymph node tuberculosis mimicking malignancy on 18F-FDG PET/CT in two patients: A case report

Abstract

¹⁸F-fluorodeoxyglucose positron emission/computed tomography (¹⁸F-FDG PET/CT) imaging, an established procedure for evaluation of malignancy, reports an increased ¹⁸F-FDG uptake in acute or chronic inflammatory condition. Lymph node tuberculosis (LNTB) is the most common form of extrapulmonary tuberculosis. However, the absence of clinical symptoms and bacteriological basis makes it difficult to diagnose. In the current case report, two patients with LNTB mimicking malignant lymphoma are presented by ¹⁸F-FDG PET/CT. The objective of the present report is to emphasize that LNTB should be considered as a noteworthy differential diagnosis in patients with enlarged lymph nodes, particularly in tuberculosis-endemic countries, and that lymph node biopsy serves a vital role in diagnosing LNTB.

Keywords: false positive; lymph node tuberculosis; malignancy; positron emission/computed tomography.

Figure 1.

(A) Coronal FDG PET/CT image of the patient in case 1. (B) Axial FDG PET/CT images of the patient. The images revealed the presence of ¹⁸F-FDG uptake in the lesions of the bilateral neck, bilateral axillary, mediastina and bilateral inguinal regions (smaller white arrows). The SUV_max of these lymph nodes was 3.8, and the presence of malignant lymphoma was suggested. In addition, the images revealed another lesion with increased FDG uptake (SUV_max, 3.6) in the neck region (large white arrows); however, the nature of this lesion could not be determined. FDG PET/CT, F-fluorodeoxyglucose positron emission/computed tomography; SUV, standard uptake value.

Figure 2.

(A and B) Pathological examination (hematoxylin and eosin; magnification, ×100) of the biopsy specimen from the cervical lymph node. The images indicate no malignant cells, caseous necrosis (black arrows) and Langhans giant cells (red arrows). The result was consistent with the characteristics of tuberculosis.

Figure 3.

(A) Coronal FDG PET/CT image of the patient in case 2. (B) Axial CT images of the patient. (C) Axial PET/CT images of the patient. The images revealed enlarged lymph nodes with increased FDG uptake (SUV_max, 5.8) in the right parapharyngeal space, bilateral carotid sheath, cervical region, bilateral supraclavicular fossa and mediastina (smaller white arrows). A mass of cavitary phthisical lesions were also demonstrated in bilateral lung tissue, with an SUV_max of 6.8 (large white arrows). A thickened right ascending colon wall with increased FDG uptake (SUV_max, 6.0) was also detected (red arrows). FDG PET/CT, F-fluorodeoxyglucose positron emission/computed tomography; SUV, standard uptake value.

Figure 4.

Pathological examination (hematoxylin and eosin; magnification, ×100) of the biopsy specimen from the cervical lymph node. Caseous necrosis (black arrows) and epithelioid cells (red arrows) are reported in this field of view.