Fine needle aspiration cytology of lymph nodes.
Lymphadenopathy is one of the commonest clinical presentations of patients, attending the outdoor department. Aetiology varies from an inflammatory process to a malignant condition. Recently, fine needle aspiration cytology (FNAC) has been successfully adopted to diagnose such lesions. It is a simple, easy technique and reports can be made available within an hour. We have performed FNAC of lymph nodes for the last five years to arrive at a diagnosis of lymphadenopathy and this forms the basis of the present report.
Three hundred and eleven patients with lymphadenopathy at various sites were subjected to FNAC technique as per method of Bloch. Smears were made, fixed immediately in ether-alcohol and stained by the haematoxylene-eosin method.
The detailed history of the patient i.e. age, sex, site and duration of involvement and other investigations performed, were recorded. The patients were followed-up. One hundred and twelve cases were subjected to lymph node biopsy. The cytological results were compared with the histological findings, wherever possible.
Out of three hundred and eleven cases, twenty five cases were deleted from the study, as the smears were inadequate and hence only 286 cases were available for study.
Only three cases were in the paediatric age group. Sixty three patients were in the range of 13-20 years. One hundred and forty six cases belonged to age group between 21 and 40 years. Fifty three patients were in the group 41 to 60 years. There were only twenty-one patients above the age of sixty years. One hundred and forty five patients were males, and 141, females.
The commonest site of lymphadenopathy was in the neck, the cervical group of lymph nodes constituting 186 cases. Among the remaining cases, 33 were axillary, 24 submandibular, 22 supra-clavicular, 13 inguinal and 8 posterior triangle groups of lymph nodes.
The cases were divided into seven groups. The brief cytological criteria adopted for classification were as follows:
1. Pyogenic lymphadenitis: revealed predominantly polymorphonuclear leukocytes, necrotic material and other lymphoid cells.
2. Non-specific lymphadenitis: showed a very cellular smear, without any necrosis. The cells consisted of lymphocytes. Plasma cells, histocytes etc.
3. Tuberculous lymphadenitis: revealed necrotic material, epitheloid cells, lymphocytes and an occasional giant cell.
4. Suggestive of tuberculose lymphadenitis: revealed only necrotic material and lymphocytes.
5. Metastatic carcinoma: showed malignant epithelial cells, usually arranged in groups or cluster, along with other lymphoid cells.
6. Lymphoma: Non-Hodgkin's lymphoma showed a monocellular pattern, consisting of lymphoblasts or lymphocytes. Hodgkin's lymphoma showed a mix cell population with the characteristic Reedsternberg giant cell.
7. Miscellaneous group: revealed characteristic other than those described in the preceding types.
The cytological results are shown in [Table1].
[Table 2] depicts the comparision of cytological and histopathological examinations of lymph nodes done in 112 cases.
Fine needle aspiration cytology has been found to be much simpler than the lymph node biopsy. The patient is free from the scar of operation. In our series, male to female ratio was equal, whereas male preponderance was seen in other series., As regards the site of FNAC, cervical region was the commonest site of lymphadenopathy, as observed by other workers.
Out of twenty cases of pyogenic lymphadenitis, seven cases revealed tubercular lymphadenitis on subsequent histological examination. This was also observed by Bailey et al and is not mentioned by any other workers. The explanation given is, when tubercle bacilli are numerous causing consequent necrosis, polymorphonuclear cells migrate at that site. Bailey et al stained such smears with Diff-Quick staining, to demonstrate other pyogenic bacilli and labelled the smears as tubercular lymphadenitis only in the absence of pyogenic organisms.
It was observed that the diagnosis of tuberculous lymphadenitis can be made definitely when granulomas composed of epitheloid cells and Langhan's cells are seen. But even in the absence of granulomas, necrosis along with the presence of lymphocytes alone gives an indirect evidence of tuberculous lymphadenitis. [Fig. 1 ].
Six cases of tuberculous lymphadenitis were misdiagnosed as chronic non-specific lymphadenitis on cytological examination. Probably, the representative sample was not obtained in these cases. This was also observed by other workers.,
Maximum number of correct diagnosis was obtained in metastatic carcinoma. There was not a single case overdiagnosed or underdiagnosed in this-group, [Fig. 2]
In the non-Hodgkin's lymphoma group, one case was of leukemic infiltration. In such cases, it is very difficult to differentiate between non-Hodgkin's lymphoma and leukemic infiltration on the examination of cytological smears alone.
Out of the two cases in the miscellaneous group, one case was diagnosed as foreign body granuloma, which was subsequently proved on histological examination. The other case revealed only large areas of necrosis and no viable cells. This was the case of melanoma, missed on cytological examination as the pigmented malignant cells were not seen in the smear.
When all the aetiological groups were considered, it was observed that a correct diagnosis was made in metastatic carcinoma. It is essential to lay down the criteria for the diagnosis of tuberculous lymphadenitis in the absence of tuberculous granulomas. A detailed study of cytologically diagnosed acute pyogenic lymphadenitis and chronic non-specific lymphadenitis by other parameters is required, as many such cases were proved to be tuberculous lymphadenitis on subsequent histological examination.