68 year old female with inguinal lymphadenopathy

Aaron Auerbach, MD, PhD

Specimen Type:

Lymph Node

History:

The patient is a 68 year old female, who presents with inguinal lymphadenopathy. She has a 9 month history of severe anemia and mild thrombocytopenia. Recent CBC: Hb 8.2 and platelets 100,000. A mass representing several right inguinal lymph nodes is completely excised.

Pathologic Features:

Histology of lymph node: The histologic sections demonstrate several lymph nodes whose architecture are replaced by large pleomorphic lymphocytes. The process extends into the peri-nodal fat and soft tissue. Many of the malignant lymphocytes have the prominent central nucleoli of immunoblasts and vesicular chromatin. Mitotic figures are prominent, and atypical mitotic figures are seen. The proliferation is diffuse, but the tumor cells in some of the slides form large nodules. Tumor necrosis is present. A smaller population of scattered background small, mature appearing lymphocytes is present. Most of the lymph nodes are entirely effaced, but some are partially effaced, and others do not appear to be involved by tumor.

Immunohistochemistry: Immunohistochemical studies show the malignant lymphocytes to be immunoreactive with Leukocyte Common Antigen (CD45), CD20, CD22, CD79, CD30 (partial), and Pax-5. The background scattered T cells are positive with CD3 and bcl-2. CD10, MUM-1, latent membrane protein, cytokeratin AE1/3, and CD5 are negative in the large lymphocytes. The proliferative rate by Ki-67 is high, expressed in approximately 100% of the large malignant lymphocytes.

Flow cytometry: Normal lymphocyte subsets include polyclonal B lymphocytes without demonstrable surface immunoglobulin light chain restriction or aberrant antigenic staining and T lymphocytes without aberrant antigenic staining.

Genetics: PCR for IgH gene rearrangement was positive for IgH rearrangement. The were no translocations involving the myc geneT(8;14) IgH/myc, T(2;8) myc/kappa or T(8;22) myc/lambda

Differential Diagnosis:

  • Diffuse large B cell lymphoma
  • Burkitt lymphoma
  • B-cell lymphoma unclassifiable with features intermediate between DLBCL and Burkitt lymphoma

Diagnosis:

Diffuse large B cell lymphoma with 100% Ki-67

Educational comments: Given the 100% proliferative rate by Ki-67 rate in the large atypical B cells, Burkitt lymphoma is a consideration. Also, the new 2008 WHO Classification of hematopoietic neoplasms, contains a new category called “B-cell lymphoma unclassifiable with features intermediate between DLBCL and Burkitt lymphoma.” In this case Burkitt lymphoma is not favored based on the lack of myc gene rearrangements, the immunophenotype (CD10-BCL2+) and the morphology. The 2008 WHO states that the category “B-cell lymphoma unclassifiable with features intermediate between DLBCL and Burkitt lymphoma,” should not be used for cases that are morphologically and phenotypic for DLBCL, but have a high Ki-67. In all, the lymphoma is best diagnosed as diffuse large B cell lymphoma.

Large B-cell lymphomas comprise about 30-40% of adult non-Hodgkin B cell lymphomas. The median age is 60 years, but the range is broad and these tumors do arise in children. Patients typically present with a rapidly enlarging mass at a single nodal or extranodal (40%) site. Although they are aggressive lymphomas, large B cell lymphomas are potentially curable with chemotherapy.

References:

  1. Steven Swerdlow, et al. WHO Classification of tumours of Haematopoietic and Lymphoid tissue. International Agency for Research on Cancer, 4th Edition, Lyon 2008.