A Practical Approach to the Diagnosis of Common Hematopoietic and Solid Tumors of Childhood
Case 9 -
Diffuse Large B-Cell Lymphoma
D. Ashley Hill, M.D.
Mihaela Onciu M.D.
17-year-old previously healthy boy presenting with small
bowel obstruction. An abdominal CT showed a terminal ileal mass. The patient underwent terminal ileal
resection. The resected mass measured 8 cm in greatest dimension and was situated 13-14 cm proximal to
the ileal-cecal valve. The margins of resection were grossly clear of tumor. No additional sites of
involvement were found at staging work-up.
Histologic sections showed an infiltrative
malignant lymphoid neoplasm with diffuse growth pattern involving all layers of the small intestinal wall
with ulceration of the overlying mucosa. Focally (<10% of the tumor) a nodular architecture was
noted. Within the diffuse and focal areas the infiltrate was composed of relatively uniform large
lymphoid cells with irregular nuclear outlines, coarsely clumped chromatin and variably prominent
peripherally-located nucleoli. Frequent mitotic figures were noted. The sampled regional mesenteric
lymph nodes showed no evidence of lymphoma.
- Diffuse large B-cell lymphoma
- Burkitt lymphoma, atypical variant
- Enteropathy-associated T-cell lymphoma.
By flow cytometry, the tumor contained a
population of large lymphoid cells that expressed CD10, CD19, CD20, CD23, and lambda light chain
restricted surface immunoglobulin, and were negative for CD34 and Tdt. Immunohistochemical staining
showed the tumor cells to strongly express CD45 and CD20, with weak expression of CD10, BCL-2 and BCL-6.
Staining for Ki-67 highlighted a proliferation fraction of ~80%. Tumor cells were negative for CD3.
The latter stain was positive in the numerous mature T-lymphocytes infiltrating the tumor.
Cytogenetic analysis revealed complex
clonal abnormalities as follows:
+22/46,XY. There was no evidence of a Burkitt-type translocation.
Molecular analysis was not performed.
Diffuse large B-cell lymphoma, centroblastic variant. The
expression of CD10, BCL-6, and BCL-2, as well as the focal nodular architecture suggest follicular center
cell differentiation in this lymphoma.