Histopathological diagnosis of lymph node biopsies and subtyping of lymphomas based on immunohistochemistry at a tertiary care centre in South Kerala

Background: Lymph node enlargement is a clinical sign with uncertain definitive diagnosis since the causes are many. In view of the wide spectrum of the possible differential diagnoses, it is imperative for the clinicians and pathologist to have a knowledge of the common causes of lymphadenopathy in their locality.Aim: To study the spectrum of histopathological diagnosis of lymph node biopsies received at a tertiary care centre in South Kerala and to find out the proportion of neoplastic and non-neoplastic lesions and to subtype lymphoma based on immunohistochemistry. Method: This work involved all the lymph node biopsies received in the department during the study period (138 cases) and their histological analysis. In all cases of lymphoproliferative disorders, immunohistochemistry was done. Results and Discussion: The male to female ratio was 1.1:1 with a slight male preponderance. The most common site biopsied was the cervical lymph node. Non-neoplastic lesions were more common and comprised 71% of all biopsies. Overall, the most common lesion was reactive lymphadenopathy. Tuberculous lymphadenitis was the next common lesion with highest incidence in individuals aged 30-39 years showing a female preponderance. Among neoplastic lesions, metastasis to lymph node showed a slight predominance over lymphoproliferative disorders. Metastasis from adenocarcinoma was the most common. All metastatic lesions were in the age group more than 30 years with a male preponderance. Non-Hodgkin’s lymphoma was more common than Hodgkin’s Lymphoma. Follicular lymphoma was the commonest among NHL. Among the 17 cases of NHL, 15 of the cases could be subtyped with the available basic IHC panel, rest 2 cases could not be precisely subtyped. All 3 cases of Hodgkin’s Lymphoma were males with Classic Hodgkin’s Disease- Mixed Cellularity type.Conclusion: In the present study of 138 lymph node biopsies, non-neoplastic lesions were more frequent than neoplastic lesions, with reactive lymphadenitis being the most common diagnosis, followed by tuberculous lymphadenitis. Among neoplastic conditions, metastatic deposits—predominantly from adenocarcinoma—were observed more frequently than lymphomas, with a predilection for older males. Non-Hodgkin’s lymphoma was more frequent than Hodgkin’s lymphoma, with follicular lymphoma being the commonest subtype identified. These findings underscore the predominance of non‑neoplastic causes of lymphadenopathy and reaffirm the critical role of histopathology, supplemented by immunohistochemistry, in arriving at a definitive diagnosis—particularly in cases where lymphoproliferative disorders are suspected.