18, NUMBER 6
Clinical Case Report
Polymerase chain reaction to identify Mycobacterium
tuberculosis in patients with tuberculous lymphadenopathy
MANAS KAMAL SEN, SOUMITESH CHAKRAVORTY, JAYA SIVASWAMI
Tuberculous lymphadenopathy is often diagnosed and treated on clinical and cytopathological
grounds as Mycobacterium tuberculosis remains undetected in tissue specimens
from such patients. At times, lymph nodes are known to respond sluggishly to
and reappear during antitubercular therapy. We report a polymerase chain reaction-based
approach to confirm the presence of M. tuberculosis in 4 such patients.
Natl Med J India 2005;18:302–3
Tuberculous lymphadenopathy commonly involves the lymph nodes
of the head and neck region.1–3 During
antitubercular therapy, up to one-fourth of such patients
changes such as enlargement, fluctuation with or without
drainage of pus in the existing nodes, and appearance of
new nodes.4 Despite efforts
at identifying the causative organism, mycobacterium tuberculosis
most often remains elusive
in tissue specimens from such patients necessitating commencement
of antitubercular therapy on the basis of clinical suspicion.
We used a polymerase chain reaction (PCR)-based method to
substantiate the aetiology in 4 such patients who responded
sluggishly to antitubercular therapy.
Four patients presented with a history of fever,
malaise and a lymph node mass in the neck. Their ages ranged from 12 to 42
years. All were city dwellers having no household contact with patients or
animals suffering from tuberculosis. None gave a history of having suffered
from a similar illness in the past. The duration of the presenting symptoms
varied from 1 to 4 months. There was no clinical or laboratory evidence of
immune compromise in any of the patients. Lymph nodes in the anterior cervical
triangle were involved in 3 patients and in the posterior triangle in 1. The
lymph nodes were solitary in 2 patients and matted in the others. They were
firm, non-tender and mobile with no evidence of fluctuation. No evidence of
pulmonary or any other systemic involvement was apparent in any of the patients.
All were tuberculin positive and non-smokers. Their blood levels of glucose,
urea, creatinine, bilirubin and transaminases, and urinalysis and chest X-ray
were within normal limits. On the basis of clinical examination, a positive
tuberculin test and fine-needle aspiration cytology suggestive of a tuberculous
aetiology, the patients were given 2 months of standard antitubercular therapy
comprising isoniazid, rifampicin, pyrazinamide and ethambutol.
However, acid-fast bacilli could not be demonstrated in any of the specimens.
All the patients showed an initial response with defervescence and a subjective
sense of well-being. The lymph nodes regressed in size after 6–10
weeks in 2 patients. One of them developed enlargement and fluctuation,
antigravity drainage of pus in the seventh week of therapy. The second patient
developed 2 small lymph nodes adjacent to the original lesion 8 weeks after
the commencement of therapy. The third patient did not show any response
to therapy till 10 weeks, when he developed two new lymph nodes in the posterior
triangle; the original lesion being in the anterior triangle. The fourth
also showed no response to therapy in terms of regression in size at the
end of 2 months; on the contrary, her lymph node enlarged, became fluctuant
tender, and required repeated antigravity aspiration and ultimately resection
at the end of 3 months of antitubercular therapy.
Specimen collection, cytological, histopathological, bacteriological and PCR
A lymph node biopsy was performed through an antigravity approach in all
these patients under local anaesthesia, using an automatic, 18 gauge, core
system echogenic needle of 15 cm length and 17 mm channel cut-specimen notch
(Microvasive®, Boston Scientific Corporation). The specimen was subjected
to analysis by histopathology, smear microscopy by Ziehl–Neelsen staining,
PCR for detection of M. tuberculosis and culture for the same bacillus (on
Lowenstein–Jensen medium). Sample preparation for smear microscopy,
culture and PCR was carried out using the Universal Sample Processing (USP)
method described by us.5 PCR
assays were performed to amplify target gene sequences—devR6 and IS 61107 of M. tuberculosis.
All the four specimens demonstrated granulomatous inflammation with caseation
necrosis, epithelioid cells and Langhan giant cells suggestive of tuberculosis
of the lymph node. Acid-fast bacilli could not be demonstrated in any of
the nodes and all were sterile on culture for M. tuberculosis. All the four
tested positive for both the target sequences by PCR.
The initial intensive phase of antitubercular therapy using 4 drugs
was, therefore, extended by 1 month in all the patients, on clinical grounds
of sluggish response
and based on the PCR results. The continuation phase comprising 3 drugs
was extended to 6 months in 3 patients and 9 months in the fourth patient in
of their sluggish response to treatment. All the 4 patients completed antitubercular
therapy (9 months in 3 patients and 12 months in 1 patient) with complete
response. None showed any adverse reaction to the drugs or relapsed while
on follow up.
Tuberculous cervical lymphadenitis is a common manifestation of extrapulmonary
tuberculosis. It has been known to affect various groups of lymph nodes
in the neck and response to therapy is the rule. However, the nodes may
palpable due to scarring and fibrosis long after there is evidence that
the disease has subsided. Uneventful resolution of the lesions is seen in
70% of patients.8 Appearance of fresh lymph nodes
and their enlargement can occur during treatment, usually followed by resolution.
At the end of therapy,
about 10% may be left with residual nodes.9 Such
transient enlargement or appearance of fresh lymph nodes does not imply relapse,
nor does the persistence
of nodes presage relapse. In one series, 2% of the patients demonstrated enlargement
of nodes during the latter half of their treatment.9 In
another report of 113 patients, 2 developed fresh lymph nodes and 10 showed
an increase in the
size of the nodes while on treatment. Although tubercle bacilli have not been
demonstrated in such lymph nodes, they show clinical features of tuberculosis
suggesting that the enlargement may be due to a reaction to a constituent
of M. tuberculosis.4
All the 4 patients had clinical and histopathological evidence of a tuberculous
aetiology. Since M. tuberculosis could not be demonstrated in any of the tissue
specimens, biopsy specimens from all the 4 patients were subjected to PCR
analysis for the detection of M. tuberculosis and were found positive. None
of the patients was immunocompromised (HIV–AIDS, neoplasms, drugs,
etc.). All were compliant with appropriate antitubercular therapy.10 No
evidence of drug resistance could be identified in any patient as the culture
However, they demonstrated features of deterioration (enlargement, abscess
formation, fresh nodes) while on therapy. The probable reasons for these include
allergic manifestations to M. tuberculosis and inability of the drugs to reach
the target areas in the lesions. The presence of M. tuberculosis DNA in tissue
specimens was demonstrated by PCR, which established the specific microbial
aetiology. The patients received an extended duration of therapy and showed
SC is thankful to the Indian Council of Medical Research for a Senior Research
Fellowship; MKS to the World Health Organization, Geneva for a short term
fellowship to work in the Department of Biotechnology, All India Institute
of Medical Sciences during which period this study was conducted. JST is grateful
to the Department of Biotechnology, Government of India and the All India
Institute of Medical Sciences for financial assistance. Technical assistance
of Mr Sanjay Kumar is also acknowledged.
Potential conflicts of interest—none.
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- Ord RJ, Matz GJ. Tuberculous
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3rd ed. Geneva:World Health Organization
Safdarjung Hospital, New Delhi
Manas Kamal Sen Department of Respiratory Medicine
All India Institute of Medical Sciences, Ansari Nagar,
New Delhi 110029, India
Soumitesh Chakravorty, Jaya Sivaswami Tyagi Department
Correspondence to Jaya Sivaswami Tyagi; email@example.com