Micronodular thymoma with lymphoid stroma: report of four cases and review of literature
LIU Shui-xian
LI Shi-rong
BAO Lu-ri
XU Xiao-yan
Abstract：Objective To study the clinipathological features of micronodular thymoma with lymphoid stroma.Methods Four cases of micronodular thymoma with lymphoid stroma were studied by histology,immunohistochemistry and clinical imaging.Results There were 2 males and 2 females with ranging in age from 52 to 69 years (mean 61 years old).Computed tomography (CT) all showed an irregular soft tissue density in thymic area,and the density was uniform.The tumors measured 2.0 cm to 6.0 cm in greatest dimension (median,3.375 cm).They mostly appeared to be well circumscribed and encapsulated,only one case seemed to have a capsule violation in a small place.The cut surface of the tumors was light tan and solid,and this texture was medium.Microscopically,MNT was characterized by multiple,discrete or focally confluent nodules of epithelioid tumor cells separated by abundant lymphoid stroma with prominent germinal centers.The epithelial nodules were composed of slender or plump spindle cells with bland looking oval nuclei and inconspicuous nuleoli.Cell atypia and mitotic activity were absent or minimal.Immunohistochemical studies showed that strong positivity of the spindle epithelial tumor cells for CK5/6,CK19,CD57 and P63.Stains for EMA were negative in the spindle tumor cells.Individual CD3,TDT-positive T cells were visible in epithelial cell nests.Many lymphocytes in the stroma,including germinal centres,were positive for CD20.In contrast,many lymphocytes positive for CD3 and CD5 were even dispersed in the stroma.BCL-2 immunoreactivity was also detected in many lymphocytes in the stroma,especially in the mantle zone of lymphoid follicles.Ki-67 showed low expression in epithelial nodules,whereas high expression in lymphocytes areas.And we found that some CD1α +,langerin + Langerhans cells were scarced within epithelial cell micronodules in a star-like pattern.Conclusions MNT is a very rare tumor but can be diagnosed with a characteristic morphology and immunoreactivity to p63 and CK5/6.We speculate that MNT is derived from the thymic medulla.In addition,we report four cases of MNT to emphasize Langerhans cell proliferation and the histopathologic features of the rare lesion and promote a better and broader understanding of this less understood subject.
Keywords：Thymus neoplasmMicronodular thymoma with lymphoid stromaLangerhans cellsImmunohistochemistry
Publication Date：2017-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：6( 818-823 )