Immunohistological Diagnosis of a B-cell Malignant Lymphoma of the Descending Colon

Abstract

A 69-year-old man complained of LUQ pain and muco-bloody stool. Lower gastrointestinal study and colonoscopy revealed an apparent submucosal tumor in the descending colon. Left hemicolectomy was performed. Postoperatively, chest tomography demonstrated a tumorous shadow in the lateral subsegment of the right lower lobe, and right lower lobectomy was performed two months after the initial operation.
There was a submucosal tumor measuring 3.5×3.5×2.0cm, with a small central ulcer in the specimen. Although routine histological examination failed to demonstrate malignant lymphoma, immunohistological studies were carried out by the avidine-biotin-complex method using monoclonal antibodies against each lymphocytes antigen. In the paraffin specimens, the diagnosis was no more than an indefinite reactive lymphoid lesion because of inadequate preservation of the antigens. Using frozen specimens of the colonic lesion, however, this lesion was definitely diagnosable as a
B-cell malignant lymphoma consisting predominantly of diffuse monoclonal proliferation of the cells. These cells produced immunoglobulin M composed of only the λ-chain, and had the same antigen, that is, B2, as most follicular cells.This immunological result and the morphological findings seemed to prove that the lesion was B-cell malignant lymphoma composed of diffuse proliferation of mature B-cells. B2 antigen has also been reported to be carried by some early B, all mature B and some large noncleaved cells.