Malignant lymphoma of mucosa‐associated lymphoid tissue arising in the thymus of a patient with sjögren's syndrome

Abstract

A 59‐year‐old woman with Sjögren's syndrome had an anterior mediastinal tumor. The tumor had epithelium‐lined thymic cysts. Histologically, centrocyte‐like (CCL) cells were present as clusters intermingling with small lymphocytes and plasma cells, invaded the epithelium, and formed characteristic lymphoepithelial lesions; the tumor was identified as malignant lymphoma arising in mucosa‐associated lymphoid tissue (MALT). Within the tumor, trapped Hassall's corpuscles were recognized. Immunohistochemical staining demonstrated monotypic cytoplasmic kappa light chains in a small portion of the CCL cells. Furthermore, Southern blot hybridization studies showed rearrangements of immunoglobulin heavy chain, immunoglobulin kappa light chain, and T‐cell receptor beta genes. The findings are consistent with thymic low‐grade B‐cell MALT lymphoma. Cancer 1992; 69:1347‐1355. Copyright © 1992 American Cancer Society