Original contributionWhat is the optimal diagnostic pathway in tuberculous lymphadenitis in the face of increasing resistance: Cytology or histology?☆,☆☆,★,★★
Introduction
Mycobacterial species first appeared 15,000 years ago [1]. Mycobacterium tuberculosis is an obligate aerobe and an acid-fast bacterium. Acid-fast bacilli (AFB) retain dyes when heated and treated with acidic organic compounds, which is the basis for pathologic identification [1]. The probability of developing active clinical tuberculosis (TB) following inhalation of an infectious droplet is less than 10% over a lifetime. Prevalence of TB depends on geographical location, strain type and immunosuppression. Human immunodeficiency virus (HIV) positive patients are twenty times more likely to develop TB [2], [3].
There are an estimated 8 million new cases of TB per annum worldwide [4]. In the United Kingdom (UK), the overall incidence of TB in 2012 was 13.9 per 100,000. Urban centres are reported to have higher incidences; the London Borough of Newham reported the highest rate of tuberculosis in the UK with 116.5 per 100,000 which is comparable to Nigeria and is the highest in Western Europe [5]. Extra-thoracic lymph node TB accounts for 20% of cases [4]. The cervical lymph nodes are the most frequently involved; historically referred to as scrofula [1], [2].
Part of the success of the organism is in the delayed presentation. Patients are frequently asymptomatic; the lymph node may grow discretely, in isolation and is usually non-tender [6]. Constitutional symptoms of weight loss, fever, malaise and night sweats are seen in only a minority of patients [7], [8].
130 years on from Koch’s discovery of tubercle bacilli, the search for effective diagnostic methods continues [9]. There is currently no single point-of-access test available that correctly diagnoses mycobacterial infection and provides sensitivities to the common antimicrobials. There are a range of tests used in tandem to diagnose and screen for TB. Immunodiagnostic tests; QuantiFERON® Gold, QuantiFERON® Gold In-Tube and the T-Spot tests measure interferon-gamma and can confirm that a patient has either active or latent TB and thus play a supportive role in screening only [10], [11]. The Mantoux tuberculin sensitivity test has significant cross-reactivity with other mycobacterium and will be positive if the patient has had a Bacillus Calmette-Guerin (BCG) vaccination, therefore its specificity is limited [10], [11].
Establishing a firm diagnosis of lymph node TB is therefore difficult but may be achieved by tissue sampling through the identification of AFB on cytology or histopathology. Evidence of granulomatous inflammation on cytology or histology may also point towards TB but has the disadvantage of being non-specific [12]. The gold standard for diagnosis and treatment is a positive culture of the mycobacterial species. There is a lack of guidance on how to best obtain a positive TB culture, especially in the face of increasing mycobacterial resistance.
In the investigation of lymphadenitis, ultrasound (US) with fine needle aspiration (FNA) is usually the first-line diagnostic test. It is quick, cheap and relatively safe. Alternatively, excision biopsy yields increased histological, culture and microscopy sensitivities, however, it is costly, labour-intensive and carries complications [13], [14], [15]. These complications include infection, damage to nearby neurovascular structures and a persistent discharging sinus.
Current challenges in TB diagnostics include the diagnostic delay, the HIV epidemic and increasing drug resistance. Difficulty in detection and failure to treat all infectious cases of TB has led to the continued transmission of the disease [2]. We present a summary of the cases of lymph node TB in a suburb of London over 34 months.
Section snippets
Methodology
Data was collected from January 2011 to October 2013 via a prospective database of all identified TB cases within the catchment area of Newham. Patients in whom there was clinical suspicion of TB had an FNA, mainly with US, with the aspirate sent for AFB microscopy and TB culture.
In our department, aspirates undergo an Auramine and Ziehl-Neelsen stain at the TB microbiology laboratory to verify the presence of AFB. The aspirate is then concentrated and transferred to culture bottles, which are
Results
There were 114 patients with extrapulmonary lymph node TB, of which 90 had clinically abnormal cervical lymph nodes. The average age was 34.7 years old (range 15–67 years old). Fifty-four percent were male and 46% female. Only 10 patients (11.1%) were born in the UK; 32 patients were from Pakistan, 25 from India and Bangladesh collectively. Those not born in the UK immigrated on average 9 years before diagnosis. Four patients had previous TB, but all completed their original course of
Discussion
Reconfiguration of referral services in the UK has guided new onset neck masses towards rapid diagnostic two-week-wait clinics, primarily in place for the expedient diagnosis and management of cancer. Such clinics are likely to attract referrals for all cervical lymphadenopathy and in high incidence urban areas may attract significant numbers of tuberculous lymphadenitis.
US guided FNA is frequently employed as the first-line investigation in two-week-wait clinics. Our data shows that if pus is
Conclusion
We suggest an algorithm applicable to all head and neck rapid diagnostic clinics for the prompt and efficient management of TB lymphadenitis.
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Cited by (9)
Head and neck tuberculosis: Literature review and meta-analysis
2019, TuberculosisCitation Excerpt :However, there was a significant publication bias for HIV co-infection (p < 0.001). The asymmetric funnel plot has shown in the Linasmita study [16], Menon study [17], Yashveer study [18] and Meghji study [19] being the source of bias (Fig. S4A). We also found publication bias for the age distribution (p = 0.037).
Empirical treatment with non-anti-tuberculosis antibiotics decreased microbiological detection in cervical tuberculous lymphadenitis
2018, Diagnostic Microbiology and Infectious DiseaseCitation Excerpt :As in our final study, only 57% CTL could be diagnosed by the presence of cytology. In line with this, FNAC cytology revealed typical tuberculous cytopathology in merely 49% (44/90) of the cohort study carried out by Meghji (Meghji and Giddings, 2015). Detection of Mtb from FNAC is not only a gold standard criteria for diagnosis of CTL, but also provides bacillus material for further species identification and drug sensitivity test, which is critical for precision anti-TB treatment regimen.
An evidence-based clinical pathway for the diagnosis of tuberculous lymphadenitis: A systematic review
2020, International Journal of Mycobacteriology
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Contributors: Each of the authors (SM and CEBG) has contributed to, read and approved this manuscript. There are no other contributors.
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Manuscript: This manuscript is original and it, or any part of it, has not been previously published; nor is it under consideration for publication elsewhere.
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Ethical approval: Not required.
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Level of evidence: 2b — individual cohort study.