Nodular histiocytic/mesothial hyperplasia:a clinicopathological analysis of six cases

REN Yuan; LI Songmei; XU Liang; CHEN Xi; LI Xiang; HUANG Shubin

doi:10.3969/j.issn.1007-8096.2025.09.015

Abstract：Objective To investigate the clinicopathological characteristics,immunophenotype and differential diagnosis of nodular histiocytic/mesothial hyperplasia(NHMH).Methods Six cases of nodular histiocytic/mesothial hyperplasia from December 2018 to December 2024 in the Department of Pathology,Chizhou People's Hospital were retrospectively analyzed.Their clinical pathological characteristics were observed,and relevant literature was reviewed.Results Among the 6 patients,4 were male and 2 were female,with an age range of 3 to 75 years and a median age of 43 years.Two cases occurred in children's spermatic cysts,two cases in tissues surrounding the malignant tumor,one case in pulmonary bullae tissue,and one case in a mediastinal mesothular cyst.Microscopically,the lesions showed similar morphology.A large number of histiocytes and a small number of mesothial cells arranged in diffuse sheets or nests.The cells in the center of the lesion were densely arranged,while those in the periphery were sparse,distributed in nests and separated by fibers.The lesion cells were relatively uniform in size,with clear boundaries,fine chromatin,round or oval nuclei.Some nuclei were shrunken,with focal nuclear grooves,and the nucleoli were not obvious.The cytoplasm of the cells in the center of the lesion was powdery and finely granular,while the cytoplasm of the surrounding cells was transparent.There was fibrous exudation and scattered lymphocyte infiltration in the stroma.Immunohistochemically,histiocytes diffusely expressed CD68 and Vimentin,scattered mesothial cells expressed Calretinin and WT-1.CD1a,Langerin,HMB45 and SALL4 were all negative.Conclusion Nodular histiocytic/mesotheric hyperplasia is a rare benign tumor-like lesion.Its morphology is easily misdiagnosed as a tumor.The differential diagnosis varies according to the site of occurrence.By combining clinicopathological characteristics with immunohistochemical findings,the diagnosis can be clarified,and excessive diagnosis and treatment can be avoided.