RSS-Feed abonnieren
DOI: 10.1055/s-0044-1788594
Imaging Features and Recent Advances in Lymph Node Tuberculosis
- Abstract
- Introduction
- Imaging Modalities
- Imaging Characteristics and Differentials in Tubercular Lymphadenopathy
- Complications
- Response Assessment
- Take Home Points
- References
Abstract
The burden of tuberculosis in our country persists, with diverse presentations affecting various organ systems, most commonly manifesting as pulmonary tuberculosis followed by nodal tuberculosis. While pulmonary involvement is frequently observed, nodal tuberculosis can present in isolation, commonly affecting cervical lymph nodes. Various imaging modalities play pivotal roles in diagnosis and assessment. Radiographs serve as initial screening modality in thoracic lymphadenopathy. Ultrasound is mostly used in cervical lymphadenopathy. Cases of thoracic and abdominal lymphadenopathy are usually evaluated with computed tomography but magnetic resonance imaging can be a radiation-free alternative. The role of fluorodeoxyglucose-positron emission tomography and newer modalities like shear-wave elastography and contrast-enhanced ultrasound are briefly discussed.
#
Introduction
Tuberculosis (TB) remains one of the leading contributors of disease burden in our country with varied presentations involving various organ systems. It can involve a single organ system or present in disseminated form. Pulmonary TB is by far the most common form, followed by nodal TB. Nodal TB is the most common form of extrapulmonary TB.
Patients of nodal TB often have a past history of inadequately treated or clinically silent pulmonary TB. Although most patients may also show pulmonary involvement on further examination and investigations, it is not uncommon to have isolated regional lymphadenopathy, most commonly seen in the cervical region.[1] Nodal TB can practically involve any region in the body.
#
Imaging Modalities
It is critical to use the imaging modalities judiciously, keeping in mind the issue of availability, as well as economic and radiation costs.
Radiographs
Chest radiograph (CR) is useful in the evaluation of thoracic lymphadenopathy for which it is the primary initial modality. A lateral radiograph improves the diagnosis of enlarged lymph nodes at several sites including hila. Large cervical lymph nodes can also be appreciated on radiographs of the neck.
#
Ultrasonography
It is a very useful modality when the target region is superficial/easily accessible and thus plays a major role in cervical lymphadenopathy. Abdominal lymphadenopathy can also be evaluated and subjected to guided-sampling on ultrasound (US). In specific situations, ultrasonography (USG) can be used in visualizing upper mediastinal lymph nodes (right and left paratracheal, prevascular, subaortic, subcarinal). In addition to superior characterization of nodal characteristics, it can be used as a valuable tool in guided sampling and follow-up of patients.
#
Computed Tomography
Contrast-enhanced computed tomography (CECT) is the most important imaging modality in intrathoracic diseases. The nature of contrast enhancement, presence or absence of calcification, and conglomeration are some of the parameters that need to be assessed on CT images. Characteristic appearance on CT includes necrotic nodes with peripheral rim enhancement, conglomerate lymphadenopathy, perinodal fat streakiness, and calcification (more prominent on treated nodes). Additional advantage includes the ability to evaluate the lungs and the osseous structures. CECT abdomen and CT enterography are useful in abdominal involvement.
#
Magnetic Resonance Imaging
On magnetic resonance imaging (MRI), three patterns can be seen—discrete, matted, and confluent. Necrosis is seen as an area of T2 hyperintensity and T1 hypointensity. Contrast administration is crucial, as presence or absence of necrosis can be confidently commented upon only on a CE-MRI. Most of the patients suffering from tubercular lymphadenopathy have to undergo repeated imaging. While superficial lymphadenopathies can be followed up on US, deeper lesions need alternate imaging modality. MRI can fit in this situation, in both abdominal as well as thoracic lymphadenopathies.
#
Fluorodeoxyglucose-Positron Emission Tomography CT
It can help in mapping the extent of the disease accurately before the initiation of therapy and also aid in confirmation of TB. Maximum standardized uptake value can be useful in monitoring treatment response.[2] [3] Major drawback of fluorodeoxyglucose-positron emission tomography (FDG-PET) imaging is that it fails to distinguish between other similar etiologies of lymph node involvement like metastases, sarcoidosis, and lymphoproliferative disorders. Lymphoma is the most common misdiagnosis. However, it can suggest the site for successful biopsy and differentiate between active and inactive nodes.[4]
#
#
Imaging Characteristics and Differentials in Tubercular Lymphadenopathy
The imaging findings and differentials are discussed site-wise (cervical, thoracic, and abdominal lymphadenopathy) below.
Cervical Lymphadenopathy
Tubercular cervical lymphadenopathy, like any other sites, classically presents with matted/conglomerated lymph nodes with or without necrosis. The main differential diagnoses include other infective causes (bacterial/viral), malignant causes (lymphoma, metastases), Kimura's disease, histiocytic disorders (Rosai–Dorfman disease), and inflammatory causes (Kawasaki disease).
While imaging is not fool proof, several imaging characteristics have been described for differentiating tubercular lymphadenopathy from other causes ([Fig. 1]). Besides gray scale USG, color Doppler USG has also proved to have diagnostic benefits in differentiating tubercular lymphadenopathy from other causes. Pattanayak et al studied the US characteristics of cervical lymph nodes in predicting the benign and malignant etiologies. Statistically significant features are listed in [Table 1].[5]
Newer imaging modalities such as shear wave elastography (SWE) and CEUS have been studied for their applications in tubercular lymph nodes. Patterns of enhancement in CEUS is studied for its utility in US classification of tuberculous lymph nodes to aid in better assessment of the disease stage.[6] More than half area of nonenhancement was found to be predictor for lymph node rupture in cervical tubercular lymphadenopathy.[7] SWE along with conventional US can help in differentiating benign from malignant lymph nodes.[8] [9]
#
Thoracic Lymphadenopathy
Thoracic lymphadenopathy is the most common site involved in lymph nodal TB. Both mediastinal as well as hilar lymph nodes can be affected. Uncommon sites include internal thoracic, epicardial, and intercostal lymph nodes.
Chest Radiograph
CR can detect mediastinal and hilar lymphadenopathy. Right paratracheal lymphadenopathy is evident by widening of right paratracheal stripe; subcarinal adenopathy is reflected by widening of the carinal angle ([Table 2], [Fig. 2]). One of the nonspecific and less described signs on lateral radiograph, “dough nut sign” refers to the radiopaque ring formed in the presence of enlarged subcarinal and hilar lymph nodes where the trachea/upper lobe bronchi form the central radiolucency. Aortic arch and pulmonary arteries form the superior and anterior aspect of the ring which is completed by the presence of enlarged lymph nodes inferiorly.
Nodes involved |
Imaging finding |
---|---|
Right paratracheal |
Widening of right paratracheal stripe (> 5 mm) |
Hilar |
Increased density and outward convex contour of hila |
Subcarinal |
Widening of carinal angle, straightening of the left main bronchus |
Azygo-esophageal |
Displacement of the azygo-esophageal line |
#
Ultrasonography
USG has an additive value in differentiation of lymph nodes from a normal or enlarged thymus. Although the lower mediastinal stations are not amenable to USG evaluation. Upper stations (4A, 4B, 3, 5, and 7) can be visualized under USG using proper technique[10] ([Fig. 3]). The technique of USG in the chest is described in [Table 3].
Abbreviations: BCV, brachiocephalic vein; IJV, internal jugular vein; SCV, subclavian vein.
#
CECT
CECT remains the workhorse of imaging in intrathoracic lymphadenopathy ([Fig. 4]). Intrathoracic lymphadenopathy, in addition to the causes listed elsewhere in the body, has a few unique differential diagnoses such as enlarged thymus or developmental cysts.
#
MRI
As described earlier, necrosis and peripheral rim enhancement can be appreciated in MRI ([Fig. 5]).
#
Differential Diagnoses
There is a myriad of etiologies leading to thoracic lymphadenopathy including the common bacterial, viral, and fungal infections. TB being the most common reason for thoracic lymphadenopathy that commonly undergoes cross-sectional evaluation. Malignant etiologies include metastases from esophageal, breast, and thyroid malignancies. Lymphoma can involve any site in the body including the mediastinum.
Detailed discussion of all differentials is beyond the scope of this article. [Table 4] describes the imaging differentials in intrathoracic lymphadenopathy ([Figs. 6] and [7]).
Size |
Findings on ultrasound |
Findings on CT |
|
---|---|---|---|
Tuberculosis |
Enlarged |
• Central hypoechoic/anechoic areas of necrosis • Conglomeration • Loss of fatty hilum • Calcification |
• Perinodal fat streakiness • Peripheral rim enhancement • Conglomeration • Calcification |
Normal lymph node |
Solitary < 15 mm Multiple < 10 mm |
Can be oval or round. Homogeneously hypoechoic with presence of fatty hilum |
Well-defined margin with clear perinodal fat, preserved hilar fat |
Reactive lymphadenopathy |
Enlarged |
Can be oval or round. Homogenously hypoechoic with presence of fatty hilum |
Well-defined margin with clear perinodal fat, preserved hilar fat |
Lymphoma |
Enlarged |
• Homogeneous, no necrosis • Compression/encasement of adjacent structures |
• Nonnecrotic • Mass effect/compression on adjacent structures |
Metastases |
Enlarged |
• Can be either homogeneous or necrotic • Solid components may appear similar to primary mass |
• Can be either homogeneous or necrotic |
Abbreviation: CT, computed tomography.
Sarcoidosis remains the major imaging differential in intrathoracic tubercular lymphadenopathy. The major differentiating points include the distribution, presence/absence of necrosis, and pattern of calcification. The most common nodes affected in thoracic TB are right paratracheal, hilar, and subcarinal; while bilateral hilar and right paratracheal are the most common nodes involved in sarcoidosis. Sarcoid lymphadenopathy is typically symmetrical, unlike TB. Lymph nodes in TB can show conglomeration and peripheral rim enhancement whereas sarcoidosis shows discrete homogeneous nodes. Pattern of calcification in tubercular lymph nodes after treatment is usually homogeneous while it is rim-like/egg-shell or punctate in sarcoidosis.[11] Although less evaluated, “cluster of black pearls” is a finding in thin CECT sections considered specific for sarcoidosis where multiple small (1–2 mm) hypodense sarcoid nodules are seen within the homogenously enhancing lymph nodes.[12] This feature is evaluated in a single study limited to thoracic and abdominal lymphadenopathy. Classical “garland triad” or “1-2-3 pattern” is described in CRs where triad consists of enlarged right paratracheal, right hilar, and left hilar lymph nodes. Further, additional presence of left-sided mediastinal/aorticopulmonary window lymph nodes is considered as “1-2-3-4” pattern.[13]
#
#
Abdominal Lymphadenopathy
Abdominal lymphadenopathy in TB can be mesenteric or retroperitoneal.
Mesenteric Adenitis
The list of differential diagnosis of mesenteric lymphadenopathy includes a vast range of abdomino-pelvic inflammatory disorders and malignant lymphadenopathy in metastases or lymphoma. While differentiating lymph nodes of lymphoma from TB, it can be done based on the presence of necrosis and calcification in the latter. One of the characteristic signs described in CT imaging of mesenteric lymphoma is “sandwich/hamburger sign” where there are homogenous large lymphonodal masses (resembling buns) interspersed between the mesenteric vessels and mesenteric fat (akin to sandwich filling) with no necrosis/calcification. It is specially described in non-Hodgkin lymphoma; however, in patients with history of transplant, possibility of posttransplant lymphoproliferative disorder needs to be considered.[14] Differentiating TB from various other causes of infective/inflammatory lymphadenopathy may not be possible on imaging alone but useful associated imaging findings such as bowel wall thickening and ileocaecal junction involvement can point toward a tubercular etiology.
#
Retroperitoneal Lymph Nodes
Similar to mesenteric adenopathy, metastases, lymphoma, and other infective/inflammatory processes remain the main differential diagnosis in retroperitoneal adenopathy. Tubercular lymph nodes classically tend to involve the upper retroperitoneal nodes, whereas lymphoma can involve infrarenal nodes as well ([Fig. 8]).
CT remains the preferred modality in evaluation of abdominal TB as it allows adequate assessment of ascites, peritoneal, and solid organs as well.[15] MRI is a useful alternative, however, with the drawback of lengthy acquisition times, motion artifacts, and relative difficulty in detection of calcified lymph nodes.[16]
#
#
#
Complications
Long-term caseous necrosis in tubercular lymphadenopathy can result in:
-
Sinus or fistula formation in neck ([Fig. 9])
-
Vascular thrombosis/narrowing: can involve arterial thrombosis, portal vein, or superior vena cava thrombosis
-
Pseudoaneurysm
-
Fibrosing mediastinitis
-
Erosion of bronchi (node-bronchial fistula, airway narrowing, or stenosis)
#
Response Assessment
Assessing response to treatment is an integral part of any treatment. Ever since the emergence of the drug-resistant strains, it has become even more important. While clinical assessment is helpful, isolated nodal disease may be difficult to assess on clinical examination alone. Therefore, imaging remains crucial in such situations. Assessing the number and size of lymph nodes has been the traditional method of response assessment.
On CR, response assessment is done based on a reduction in size and appearance of calcification.
On US, the nodes may show a reduction in size and area of anechoic necrotic area, and appearance of calcification on treatment. After adequate treatment, on CT, there may be appearance of calcification (diffuse, coarse, eggshell) and lack of perinodal fat streakiness ([Fig. 10]). The presence and pattern of calcification, however, does not always denote good response to therapy.[17]
On MRI, decrease in T1 and T2 signal intensities and change of enhancement pattern from peripheral/rim to solid or nonenhancement can suggest response to treatment ([Fig. 11]). Some recent studies have explored the importance of nodal signal characteristics on T1- and T2-weighted images, without the use for CE sequences. It was observed that with treatment, there is a decrease in T1 and T2 signal in the nodes, along with size reduction. Additional imaging with apparent diffusion coefficient values were not contributory in the assessment.[18] Since these patients require repeated imaging, an imaging modality with no radiation burden as in MRI can be an effective alternative to CT in appropriate cases.
18F-FDG-PET can prove useful in equivocal treatment response, or persistent nodal disease.
#
Take Home Points
-
In conclusion, assessment of tubercular lymphadenopathy requires a multimodality approach; depending on the site involved.
-
USG is the most commonly used modality in cervical lymphadenopathy with its role in mediastinal lymphadenopathy briefly explained.
-
CT is the most used modality in thoracic and abdominal lymphadenopathy and one must be familiar with the posttreatment features.
-
MRI can be a suitable alternative to repeat CT scans on follow-up imaging.
#
#
Conflict of Interest
None declared.
-
References
- 1 Gupta A, Kunder S, Hazra D, Shenoy VP, Chawla K. Tubercular lymphadenitis in the 21st century: a 5-year single-center retrospective study from South India. Int J Mycobacteriol 2021; 10 (02) 162-165
- 2 Lefebvre N, Argemi X, Meyer N. et al. Clinical usefulness of 18F-FDG PET/CT for initial staging and assessment of treatment efficacy in patients with lymph node tuberculosis. Nucl Med Biol 2017; 50: 17-24
- 3 Sathekge M, Maes A, D'Asseler Y, Vorster M, Gongxeka H, Van de Wiele C. Tuberculous lymphadenitis: FDG PET and CT findings in responsive and nonresponsive disease. Eur J Nucl Med Mol Imaging 2012; 39 (07) 1184-1190
- 4 Liao F, Huang Z, Xu R. et al. Analysis of misdiagnosis and 18F-FDG PET/CT findings of lymph node tuberculosis. J XRay Sci Technol 2022; 30 (05) 941-951
- 5 Pattanayak S, Chatterjee S, Ravikumar R, Nijhawan VS, Vivek Sharma, Debnath J. Ultrasound evaluation of cervical lymphadenopathy: can it reduce the need of histopathology/cytopathology?. Med J Armed Forces India 2018; 74 (03) 227-234
- 6 Zhang Y, Yu T, Su D, Tang W, Yang G. Value of contrast-enhanced ultrasound in the ultrasound classification of cervical tuberculous lymphadenitis. Front Med (Lausanne) 2022; 9: 898688
- 7 Zhao D, Feng N, He N, Chu J, Shao Y, Zhang W. Application of ultrasound multimodal imaging in the prediction of cervical tuberculous lymphadenitis rupture. Epidemiol Infect 2024; 152: e28
- 8 Sun Y, Wang W, Mi C, Zhang Q, Zhang K. Differential diagnosis value of shear-wave elastography for superficial enlarged lymph nodes. Front Oncol 2022; 12: 908085
- 9 Zhang X, Wang L, Feng N, Ni T, Tang W. Reassessing the value of contrast-enhanced ultrasonography in differential diagnosis of cervical tuberculous lymphadenitis and lymph node metastasis of papillary thyroid carcinoma. Front Oncol 2021; 11: 694449
- 10 Bhalla D, Sinha P, Naranje P. et al. Transcutaneous mediastinal ultrasonography for lymphadenopathy in children: a pictorial essay of technique and imaging findings. J Ultrasound Med 2022; 41 (03) 773-783
- 11 Bhalla AS, Das A, Naranje P, Goyal A, Guleria R, Khilnani GC. Dilemma of diagnosing thoracic sarcoidosis in tuberculosis endemic regions: an imaging-based approach. Part 1. Indian J Radiol Imaging 2017; 27 (04) 369-379
- 12 Venkata Ramanan R, Pudhiavan A, Venkataramanan A. The “cluster of black pearls” sign of sarcoid lymphadenopathy: a new sign on thin-section contrast-enhanced multidetector CT. Clin Radiol 2017; 72 (09) 729-736
- 13 Lee GM, Pope K, Meek L, Chung JH, Hobbs SB, Walker CM. Sarcoidosis: a diagnosis of exclusion. AJR Am J Roentgenol 2020; 214 (01) 50-58
- 14 Alessandrino F, DiPiro PJ, Jagannathan JP. et al. Multimodality imaging of indolent B cell lymphoma from diagnosis to transformation: what every radiologist should know. Insights Imaging 2019; 10 (01) 25
- 15 Ionescu S, Nicolescu AC, Madge OL, Marincas M, Radu M, Simion L. Differential diagnosis of abdominal tuberculosis in the adult-literature review. Diagnostics (Basel) 2021; 11 (12) 2362
- 16 Zulfiqar M, Shetty A, Tsai R, Gagnon MH, Balfe DM, Mellnick VM. Diagnostic approach to benign and malignant calcifications in the abdomen and pelvis. Radiographics 2020; 40 (03) 731-753
- 17 Je B-K, Kim MJ, Kim S-B, Park DW, Kim TK, Lee NJ. Detailed nodal features of cervical tuberculous lymphadenitis on serial neck computed tomography before and after chemotherapy: focus on the relation between clinical outcomes and computed tomography features. J Comput Assist Tomogr 2005; 29 (06) 889-894
- 18 Singh R, Naranje P, Bhalla AS, Pandey S. Magnetic resonance imaging in response assessment of mediastinal tuberculous lymphadenopathy: going beyond size. Lung India 2021; 38 (05) 431-437
Address for correspondence
Publikationsverlauf
Artikel online veröffentlicht:
31. Juli 2024
© 2024. Indographics. This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/)
Thieme Medical and Scientific Publishers Pvt. Ltd.
A-12, 2nd Floor, Sector 2, Noida-201301 UP, India
-
References
- 1 Gupta A, Kunder S, Hazra D, Shenoy VP, Chawla K. Tubercular lymphadenitis in the 21st century: a 5-year single-center retrospective study from South India. Int J Mycobacteriol 2021; 10 (02) 162-165
- 2 Lefebvre N, Argemi X, Meyer N. et al. Clinical usefulness of 18F-FDG PET/CT for initial staging and assessment of treatment efficacy in patients with lymph node tuberculosis. Nucl Med Biol 2017; 50: 17-24
- 3 Sathekge M, Maes A, D'Asseler Y, Vorster M, Gongxeka H, Van de Wiele C. Tuberculous lymphadenitis: FDG PET and CT findings in responsive and nonresponsive disease. Eur J Nucl Med Mol Imaging 2012; 39 (07) 1184-1190
- 4 Liao F, Huang Z, Xu R. et al. Analysis of misdiagnosis and 18F-FDG PET/CT findings of lymph node tuberculosis. J XRay Sci Technol 2022; 30 (05) 941-951
- 5 Pattanayak S, Chatterjee S, Ravikumar R, Nijhawan VS, Vivek Sharma, Debnath J. Ultrasound evaluation of cervical lymphadenopathy: can it reduce the need of histopathology/cytopathology?. Med J Armed Forces India 2018; 74 (03) 227-234
- 6 Zhang Y, Yu T, Su D, Tang W, Yang G. Value of contrast-enhanced ultrasound in the ultrasound classification of cervical tuberculous lymphadenitis. Front Med (Lausanne) 2022; 9: 898688
- 7 Zhao D, Feng N, He N, Chu J, Shao Y, Zhang W. Application of ultrasound multimodal imaging in the prediction of cervical tuberculous lymphadenitis rupture. Epidemiol Infect 2024; 152: e28
- 8 Sun Y, Wang W, Mi C, Zhang Q, Zhang K. Differential diagnosis value of shear-wave elastography for superficial enlarged lymph nodes. Front Oncol 2022; 12: 908085
- 9 Zhang X, Wang L, Feng N, Ni T, Tang W. Reassessing the value of contrast-enhanced ultrasonography in differential diagnosis of cervical tuberculous lymphadenitis and lymph node metastasis of papillary thyroid carcinoma. Front Oncol 2021; 11: 694449
- 10 Bhalla D, Sinha P, Naranje P. et al. Transcutaneous mediastinal ultrasonography for lymphadenopathy in children: a pictorial essay of technique and imaging findings. J Ultrasound Med 2022; 41 (03) 773-783
- 11 Bhalla AS, Das A, Naranje P, Goyal A, Guleria R, Khilnani GC. Dilemma of diagnosing thoracic sarcoidosis in tuberculosis endemic regions: an imaging-based approach. Part 1. Indian J Radiol Imaging 2017; 27 (04) 369-379
- 12 Venkata Ramanan R, Pudhiavan A, Venkataramanan A. The “cluster of black pearls” sign of sarcoid lymphadenopathy: a new sign on thin-section contrast-enhanced multidetector CT. Clin Radiol 2017; 72 (09) 729-736
- 13 Lee GM, Pope K, Meek L, Chung JH, Hobbs SB, Walker CM. Sarcoidosis: a diagnosis of exclusion. AJR Am J Roentgenol 2020; 214 (01) 50-58
- 14 Alessandrino F, DiPiro PJ, Jagannathan JP. et al. Multimodality imaging of indolent B cell lymphoma from diagnosis to transformation: what every radiologist should know. Insights Imaging 2019; 10 (01) 25
- 15 Ionescu S, Nicolescu AC, Madge OL, Marincas M, Radu M, Simion L. Differential diagnosis of abdominal tuberculosis in the adult-literature review. Diagnostics (Basel) 2021; 11 (12) 2362
- 16 Zulfiqar M, Shetty A, Tsai R, Gagnon MH, Balfe DM, Mellnick VM. Diagnostic approach to benign and malignant calcifications in the abdomen and pelvis. Radiographics 2020; 40 (03) 731-753
- 17 Je B-K, Kim MJ, Kim S-B, Park DW, Kim TK, Lee NJ. Detailed nodal features of cervical tuberculous lymphadenitis on serial neck computed tomography before and after chemotherapy: focus on the relation between clinical outcomes and computed tomography features. J Comput Assist Tomogr 2005; 29 (06) 889-894
- 18 Singh R, Naranje P, Bhalla AS, Pandey S. Magnetic resonance imaging in response assessment of mediastinal tuberculous lymphadenopathy: going beyond size. Lung India 2021; 38 (05) 431-437