LAUSR

A 26-year-old-man presented to the hospital with abdominal pain. Abdominal imaging showed acute appendicitis, and the patient underwent an appendectomy. The appendectomy specimen showed extensive involvement of the wall of the appendix by a diffuse infiltrate of medium-sized atypical lymphocytes with abundant coarse apoptotic debris in the background, which imparted a “starry-sky” appearance to the infiltrate (panel A; hematoxylin and eosin stain, 340 objective; total magnification 3400). By immunohistochemistry, the atypical lymphocytes expressed CD20 (panel B; 340 objective; total magnification 3400), c-Myc (panel C; 340 objective; total magnification 3400), and CD10 (panel D; 340 objective; total magnification 3400) and lacked BCL2 (panel E; 340 objective; total magnification 3400). In addition, the atypical cells expressed BCL6 and lacked TdT, CD34, MUM1, and EBER. Ki-67 showed a very high proliferation rate of .95% (panel F; 340 objective; total magnification 3400). Fluorescence in situ hybridization (FISH) for a MYC rearrangement was negative, and single-nucleotide polymorphism (SNP) array revealed a proximal (centromeric) gain in segment 11q12.1-q23.3 and distal (telomeric) loss in segment 11q23.3-qter on the long arm of chromosome 11 (panel G; SNP-array results for chromosome 11). The case was diagnosed as Burkitt-like lymphoma with 11q aberration.