Lymphomas in Ile-Ife, Nigeria: Immunohistochemical Characterization and Detection of Epstein-Barr virus Encoded RNA

Abstract

Background: The proper histopathological characterization of malignant lymphomas requires the use of immunohistochemistry along with other molecular pathology techniques.

Materials and methods: Malignant lymphomas histologically diagnosed in our hospital were reclassified according to the WHO scheme using immunohistochemistry while in-situ hybridization was performed for the detection of Epstein-Barr virus encoded RNA.

Results: There were 83 cases of lymphoma. The male to female ratio was 1.9:1 while the overall mean age was 41.7 years. Non-Hodgkin lymphomas (NHL) constituted about 79.5% of cases. The majority of cases (98.8%) were B-cell lymphomas. Nine subtypes of lymphomas were identified with diffuse large B-cell lymphomas (56.4% of which were of the germinal centre type) constituting the largest group (47.0%). Intermediate and high grade subtypes were more common. The majority of cases (72.3%) were nodal lymphomas with cervical lymph node being the commonest site (48.2%). Only classical Hodgkin lymphoma (HL) (20.5%) was seen of which the mixed cellularity subtype was the most common. Epstein Barr virus (EBV) encoded ribonucleic acid was detected in 7 cases (8.4%) including 4 cases of HL, 2 cases of Burkitt lymphoma and the only case of plasmablastic lymphoma. About five cases were reclassified as non-lymphoid malignant lesions.

Conclusion: Immunohistochemistry is vital to the proper classification of lymphomas even in a resource poor environment. Although nine subtypes of lymphomas were identified, diffuse large B-cell lymphomas formed the largest single group. Epstein-Barr virus probably plays an important role in lymphomatogenesis in this environment. A larger multicentre study is required to prove this.

Keywords: Classification; Immunohistochemistry.

[Table/Fig-2]:

Age and sex distribution of cases of malignant lymphoma

[Table/Fig-5a-c]:

Photomicrographs of Classical Hodgkin’s lymphoma showing: (A) The histological features on haematoxylin and eosin (X400), (B) CD 30 positive Reed-Sternberg cells (X40), (C) Reed-Sternberg cells with nuclear staining for EBV encoded RNA

[Table/Fig-6a,b]:

Photomicrographs of diffuse large B-cell lymphoma showing: (A) The histological features on routine haematoxylin and eosin (X100) (B) Diffuse CD 20 expression pattern (X60)

[Table/Fig-7a-d]:

Photomicrograph of Burkitt Lymphoma showing: (A) The histological features on haematoxylin and eosin (X40), (B) The typical ‘starry-sky appearance on Giemsa (X40), (C) CD 20 expression pattern (X40), (D) Tumour cells with nuclear staining for EBV encoded RNA (X80)

[Table/Fig-8a-d]:

Photomicrograph of follicular lymphoma showing: (A) The nodular growth pattern on haematoxylin and eosin (X40), (B) CD 20 expression pattern (X40), (C) BCL-2 expression (X40), (D) Ki-67 expression (X40)

[Table/Fig-9a-d]:

Photomicrograph of anaplastic large cell lymphoma showing: (A) The histological features on routine haematoxylin and eosin (X100), (B) Lack of CD 20 expression (X100), (C) CD 30 expression (X100), (D) Ki-67 index (X100)