CD56 is Expressed in Uterine Smooth Muscle Tumors

CD56 is used in gynecologic pathology, typically in the context of a neuroendocrine, sex cord or sex cord-like tumor. It has never been studied in uterine smooth muscle tumors, which can potentially enter their differential diagnosis, and thus CD56 positivity could potentially be a pitfall. Thus, the aim of this study was to explore its expression in this category of tumors. Seventy-eight uterine smooth muscle tumors, including 14 leiomyosarcomas, 46 leiomyomas and their variants, 14 smooth muscle tumors of uncertain malignant potential, and 4 intravenous leiomyomatoses were studied in regard to CD56 expression. Fifty-eight nearby myometria were also analyzed. Sixty-five (83.4%) tumors showed CD56 expression. Nearby myometrium showed CD56 expression in 15 cases (25.9%). Staining ranged from 10% to 100% of tumor or myometrial cells (median 80% and 50%, respectively). Among the tumor types, leiomyoma with bizarre nuclei, had the lowest extensive expression (P=0.01). Most uterine smooth muscle neoplasms express CD56; thus, it is not useful in attempting to discriminate from endometrial stromal or sex cord-like neoplasms.

Automated summary

The study aimed to explore the expression of CD56 in uterine smooth muscle tumors, and found that most of these tumors express CD56, which is not useful in discriminating them from endometrial stromal or sex cord-like neoplasms.