Primary Mediastinal Large B-Cell Lymphoma and Its Mimickers: A Rare Case Report With Literature Review
- Author:
Thin Thin Win
;
Zaleha Kamaludin
;
Azlan Husin
- Publication Type:Case Reports
- Keywords:
Primary mediastinal large B-cell lymphoma;
non-Hodgkin lymphoma;
thymoma;
immunohistochemical staining
- From:The Malaysian Journal of Pathology
2016;38(2):153-157
- CountryMalaysia
- Language:English
-
Abstract:
Primary mediastinal large B-cell lymphoma (PMLBL) is an uncommon non-Hodgkin lymphoma
with a distinct clinicopathological entity in the WHO classification of lymphoid malignancies. It is
known to originate from B-cells of the thymus. It mimics thymic neoplasms and other lymphomas
clinically and histopathologically. We reported a 33-year-old obese man who presented with shortness
of breath off and on for 4 years. Radiologically, there was a huge anterior mediastinal mass. Tru-cut
biopsy was initially diagnosed as type-A thymoma. Histopathological examination of the excised
specimen revealed PMLBL with stromal fibrosis and sclerosis which created a diagnostic difficulty.
The neoplastic cells varied from medium-sized to large pleomorphic cells, including mononuclear
cells with centroblastic and immunoblastic features as well as bi-lobed Reed Sternberg (RS)-like
cells and horse-shoe like hallmark cells. Some interlacing spindle cells and epithelioid cells were
also present. Immunohistochemically, tumour cells expressed diffuse positivity for LCA, CD20,
CD79a, CD23, Bcl2, MUM-1 and heterogenous positivity for CD30 and EMA, and were negative
for CD10, CD15 and ALK. Ki67 scoring was very high. Tumour cells infiltrated into peri-thymic
fat and pericardium. No malignant cells were detected in the pleural fluid and there was no bone
marrow infiltration. The patient showed partial response to 6 cycles of RICE chemotherapy, and was
planned for second line chemotherapy using hyper-CVAD regimen followed by autologous stem cell
transplantation. This case illustrates the importance of thorough sampling and immunohistochemistry
in differentiating PMLBL from its differential diagnoses.
- Full text:P020161005044152902289.pdf
