Diagnostic value of dystrophin immunostaining for histopathologic diagnosis of uterine smooth muscle tumors.

Uterine smooth muscle tumors are a heterogeneous group of mesenchymal neoplasms with diagnostic challenges and overlapping histopathologic features. Recently, the molecular or immunohistochemical evaluation of dystrophin in the diagnosis of mesenchymal tumors with muscle differentiation has gained attention. In this retrospective study, the immunohistochemical expression of dystrophin was examined in 105 cases of uterine smooth muscle neoplasms, including 71 cases of leiomyoma (LM) and its variants, 6 cases of smooth muscle tumor of uncertain malignant potential (STUMP), and 28 cases of leiomyosarcoma (LMS). After thorough analysis, dystrophin expression was positive in 83.3 % of STUMP cases and 96.7 % of leiomyoma cases. In contrast, only 8 cases of LMS (28.6 %) expressed dystrophin. A significant difference in dystrophin expression was noted between STUMP and LMS, as well as LMS and LM and its variants. The median H-score in LM was significantly higher than in leiomyoma variants, STUMP, and LMS. In conclusion, dystrophin expression may be useful in distinguishing uterine LM, LM variants, and STUMP from LMS.