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Indian Journal of Community Medicine

Incidence of Tuberculosis from Study of Fine-Needle Aspiration Cytology in Lymphadenopathy and Acid-Fast Staining

Author(s): S.S. Ahmad1, S. Akhtar1, K. Akhtar1, S. Naseem1, T. Mansoor2, S. Khalil3

Vol. 30, No. 2 (2005-04 - 2005-06)

Abstract

Research question: What is the incidence of benign (tuberculosis in particular) disorders on fine needle aspiration of lymph nodes? Objective: To study the incidence of benign (tuberculosis in particular) disorders on lymph node aspiration with special reference to acid fast staining in cases of tuberculosis. Study Design: One year incidence study based on fine needle aspiration of lymph nodes; Haematoxylin & eosin and Papanicolaou staining with Ziehl-Neelsen staining for AFB/tubercle bacilli. Setting: Patients with enlarged lymph nodes attending Department of Pathology, J.N. Medical College. Study Population: 864 patients ranging from 2 years to 95 years. Study Variables: Age, sex, incidence. Statistical Analysis: Incidence of reactive and tubercular cases. Results: 62% incidence of reactive lymphadenopathy and 38% incidence of tuberculosis, Z-N positive for acid fast bacili 46.4%, with 54.9% mantoux positive. Conclusion: Fine needle aspiration cytology of superficial lymph nodes is an investigation of utility in cases of tuberculosis. Key Words: Lymph Node Aspiration, Tubrculosis Incidence, Z-N stain for AFB / Tubercle Bacilli.

Introduction:

Superficial lymphadenopathy is a common clinical finding. Fine needle aspiration cytology (FNAC) is a simple and rapid diagnostic technique.

The present study aims to characterize the incidence of different types of lymphadenopathies and performing acid fast staining in suspected cases of tuberculosis. This is of particular importance in view of the high prevalence of tuberculosis in our country, atypical presentation of tuberculosis and because of the fact that AFB are seen mostly in purulent aspirate smears, which do not show granuloma, necrosis or epithelioid cells and which in the absence of Ziehl Neelsen staining can be dismissed as acute suppurative lymphadenitis1.

Materials and Methods

The present study on 864 patients of lymphadenopathy between 2 years to 95 years of age was conducted in the Department of Pathology, JN Medical College, AMU, Aligarh, during the year 2002-2003.

FNAC of the enlarged lymphnodes was performed with informed consent of the patient, following thorough clinical examination; using a 25 G needle and syringe. In all the cases, alcohol fixed smears were made, and stained with Haematoxylin & Eosin and Papanicolaou stains; and for each case an additional slide was kept unstained. In all cases where the cytological diagnosis was of a granulomatous disease, Ziehl Neelsen staining was performed to see for acid-fast/ tubercular bacilli.

Furthermore, the clinical characteristic of lymphnodes were studied and correlated to cytological findings to ascertain the incidence of tuberculosis in the community at large.

Results

Out of the 864 cases, 536 cases were of reactive nature and 328 cases were tubercular. Among the 536 cases of reactive lymphadenopathy, 321 (62.2%) cases were reported in males and remaining 215 (37.7%) cases in females. Male to female ratio being 1.7: 1. The age of patients ranged from 2 to 95 years, thus showing a wide range of distribution of cases from early life to advanced age.

Table I - Allocation of patients with tubercular
lymphadenopathy in relation to age group and sex.

Age group
(in yrs)
Males Females Total Percentage
0-10 59 27 86 26.2
11-20 45 50 95 28.9
21-30 35 33 68 20.7
31-40 20 26 46 14.0
41-50 12 9 21 6.4
51-60 3 4 7 2.3
>61 3 2 5 1.5
Total 177 157 328 100

Clinical characterization of lymph nodes was done, and on correlation with the cytological findings, we came to the assertion that lymph nodes size was less than 1 cm in 80% cases of reactive lymphadenopathy, whereas it was over 1 cm in size in 84% cases of tubercular lympahadenopathy. 95% cases of reactive showed discrete lymph nodes whereas 60% of cases with tubercular lymphadenopathy had matted lymph nodes. Reactive and tubercular group of lymphadenopathies had non-adherent lymph nodes in 97% and 80% cases respectively.

Tubercular lymphadenopathy formed the second largest group of patients comprising of 38% of the total cases. The cytologic findings in a case of tuberculosis comprised of epithelioid cell granulomas with or without langhan's giant cells with necrosis and caseation, or smears with only necrotic material consisting of diffuse granular debris.

Out of the 328 cases of tubercular lymphadenitis, 177 cases were reported in males and remaining 157 cases in females, the sex ratio being 1.2:1. Age of patients presenting with tuberculor lymphadenitis ranged from 2 years to 75 years.

The peak incidence was reported in the second decade of life forming 28.9% of total cases, followed by equally high incidence in the first decade, 26.2%. From the third decade onwards the incidence followed a decreasing trend (Table-1). Out of the 328 cases of tubercular lymphadenopathy, Ziehl Neelsen positivity for acid-fast bacilli was found in 152 (46.4%) cases. In these cases the bacilli were usually found extracellularly, in the areas of microscopic degeneration within or at the periphery of the granuloms. The morphology of tubercle bacilli in smears was as short and stumpy rods. The highest yield of acid-fast bacilli was found in purulent smears (68.8%); closely followed by 54.3% in cheesy or caseous smears, whereas only 19.3% in aspirates mixed with blood.

Out of 328 cases of tuberculosis, 180 cases were mantoux positive. (Mantoux positive was considered when the erythema was present along with induration which was more than or equal to 10 mm in size, 72 hours after intra-dermal injection of 0.1ml of PPD on the flexor surface of the forearm). Rest 148 cases were mantoux negative.

Discussion

Enlarged and generally symptomatic lymphadenopathy most frequently involving head neck, axilla and inguinal regions are relatively common clinical findings. Their etiology range from simple reactive hyperplasia to tuberculosis and malignancies. Fine needle aspiration is a simple and rapid diagnositc technique for evaluation of lymphadenopathy.

The lesions arising in the lymph node can be found in patients ranging from early to advanced age. In our study youngest patient was 2 year old and oldest was 95 years of age. These figures come in close comparison to a study2 of 1,103 patients where youngest patient was 1 year old and oldest being 90 years.

A sex ratio in cases of reactive lymphadenitis was 1.7:1 with a male predominance. Stain3 also reported sex ratio of 2:1, with definite male predominance. Similarly, a male predominance was noted by us in cases of tubercular lymphodenopathy, with a male to female ratio of 1.2:1. This result is in agreement with the finding of Rajasekaran et al4 and Bailey et al5. The described 1.3:1 and 1.4:1 male to female ratio respectively in tubercular lymphadenities while few other workers like Pamra et al6 have shown a female predominance.

Regarding the correlation of the clinical characteristics of lymph glands to cytological impression, it was observed by us that reactive glands were mostly less than 1 cm in size (80% cases where tubercular glands were over 1 cm in majority of cases (84.8%). These findings are in accordance with that of Bedi et al7 (1987), who reported lymph nodes of over 1 cm size in reactive and tubercular lesions as 28% and 90%, respectively. Matted lymph nodes were seen in 60% cases of tubercular lymphadenitis, whereas discrete lymph nodes were seen in 95.3% of reactive lesions. Similar findings were observed by other workers6,7. They found matted lymph nodes as one of the characteristic features of tubercular lymphadenitis.

In our study we found 328 (38%) cases of tubercular lymphadenopathy. This finding was in concordance with others8,9. These observations were slightly higher than that given by Dev Prasoon10, who noted a percentage of 27.3% in 783 cases analyzed during their study. This discrepancy could be due to failed antitubercular drug therapy or resistent strains of mycobacterium.

Maximum number of patients of tuberculosis in our study were from the age group to 11-20 years followed by age groups of 0-10 and 21-30 years. A declining trend was noted in incidence of tubercular lymphadenitis after 30 years of age, which was in concordance with other workers6,7. It may be due to the development of immunity in older patients.

Out of 328 cases of tubercular lymphadenopathy, 152 (46.4%) cases showed acid fast or Ziehl-Neelsen staining positivity. Our findings correlate with that of Dev Prasoon10, who reported stainable acid fast/tubercle bacilli in 46% and 40.8% respectively. Pamra et al6 however, reported a lower AFB smear positivity rate i.e. 35.6% in their studies.

The highest rate of acid fast bacilli positively in the smear stained by Ziehl-Neelsen technique was found in cases where purulent material was aspirated (68.8%). Our findings correlate very well with findings of other authors1-10, who also found highest yield of tubercle bacilli in aspirates which were purulent in gross appearance.

Mantoux test in our study was found to be positive in only 180 (54.9%) cases of tuberculosis. It is probably due to the fact that in majority of patients with tuberculosis, the cellular immune response may be depressed11. It means that a negative tuberculin/mantoux test cannot be relied upon to exclude tuberculosis. Also the validity of tuberculin test in subjected to variability. It is limited by lack of specificity. Apart from errors associated with the mode of administration, reading of results and the test material used; there are other factors such as cross-reaction, due to sensitization by other mycobacteria which have to taken into account. Therefore, utility of the tuberculin/mantoux test as a diagnostic criterion is again very limited, and primarily so because of its interpretation. Others7,11 have also supported this view on mantoux test in tuberculosis.

Conclusion:

Thus, combination of the needle aspiration cytology with acid fast staining is highly valuable for routine diagnosis of tuberculosis. Other ancillary investigations like mycobacterial culture, lymph node biopsies and polymerase chain reaction can be reserved for cases, in which there is a strong clinical suspicion with equivocal result of FNAC and acid-fast staining.

References:

  1. Metre MS, Jayaram G: Acid fast bacilli in aspiration smears from tuberculous lymphnodes : Acta Cytol. 1987; 31:17-19.
  2. Steel BL, Schwartz MR, Ibrahim R: Fine needle aspiration biopsy in the diagnosis of lymphadenopathy in 1,103 patients. Acta Cytol. 1995; 38:76-81.
  3. Stain J: Cytologic diagnosis of reactive lymphadenopathy in FNAB specimens. Acta Cytol. 1987; 31:8-13.
  4. Rajsekaran S, Gunasekaran M, Bhanumati V: Tuberculous cervical lymphadenitis in HIV positive and negative patients. Ind J Tub. 2001; 48: 201-204.
  5. Bailey TM, Akhtar M, Ali MA : Fine needle aspiration biopsy in the diagnosis of tuberculosis. Acta Cytol. 1985; 29: 732- 736.
  6. Pamra SR, Baily GVS, Gupta SP et al: Cervical lymphadenopathies. Ind J Tub. 1987; 96-100.
  7. Bedi RS, Third GS, Arora VK: A clinico-pathological study of superficial lymphadenopathy in northern India. Ind J Tub. 1987; 34-: 189-191.
  8. Tilak V, Dhadel AV, Jain R: Fine needle aspiration cytology of head and neck masses. India J Path Microbiol. 2002; 45 (1); 23-30.
  9. Narang P, Narang R. Mendratle BR, Nayar S: Field study to evaluate the bacteriological parameters in the diagnosis of lymphonde tuberculosis in children. Ind J Tub. 1998. 45:211-214.
  10. Prasoon D. : Acid-fast bacilli in FNA Smears from tuberculous lymphnodes. Acta Cytol. 2000; 44: 297-300.
  11. Park K: Textbook of preventive and social medicine, 17th Edn. 2002; 202-206.

Deptt. of Pathology1, Surgery2 and Social Medicine3 J.N. Medical College, Aligarh Muslim University, Aligarh.

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