Lly seeding the peritoneum with small pieces of both neoplastic and non-neoplastic material. This phenomenon is compounded with the fact that some CX-5461 morcellated tumors are not benign [2]. The purpose of this study was to determine the frequency of a post-operative histologic diagnosis of malignancy (leiomyosarcoma), problematic smooth muscle tumors (atypical leiomyoma, smooth muscle tumor of uncertain malignant potential), or variant leiomyomas (e.g. cellular leiomyoma) following power morcellation at a major urban academic medical center, where over 1,000 hysterectomies are performed annually [3]. Additionally, this study determined the frequency of iatrogenic peritoneal dissemination of these lesions secondary to powerMorcellation and Peritoneal DisseminationFigure 1. Representative histologic fields of several of the most common diagnoses reviewed during this study. Leiomyoma (case previously published) [6] is characterized by smooth muscle cells without atypia, mitoses, or necrosis. In contrast, atypical leiomyoma (case #7) shows atypia, but rare mitoses (up to 2 mitoses per 10 high power fields). Smooth muscle tumor of uncertain malignant potential (STUMP, case #11) is characterized by a higher rate of mitoses (3 to 8 mitoses per 10 high power fields) and more frequent atypia. Leiomyosarcoma (LMS, case #15) shows significant mitotic activity (over 10 mitoses per 10 high power fields), prominent atypia, and tumor necrosis. doi:10.1371/journal.pone.0050058.gmorcellation and the clinical outcomes data associated with such complications.Methods Ethics StatementAll materials from this study were collected in the course of clinical care prior to the start of any research. Research was performed only on discarded tissue, i.e. material deemed not necessary for clinical diagnostics or care. Clinical information used in the study was entirely anonymized from the medical record in accordance with current national guidelines. The Institutional Review Board at Brigham Women’s Hospital evaluated and approved all aspects of this research, and deemed the procedure eligible for expedited review not requiring subject consent.were identified that contained the keyword “morcellation” or “morcellated” as well as the keyword “uterus”, and that were performed for the indication of uterine leiomyoma, as per the medical record. The search term “leiomyosarcoma” was omitted to avoid case selection bias; however, when this term was included, no additional cases meeting study criteria were identified.Specimen EvaluationHistologic evaluation of morcellated specimens was 1407003 performed by taking one section of tissue for every 1 cm of the original radiologically reported greatest dimension of the lesion. This was felt to best recapitulate the degree of sampling that would be performed on an equivalent en bloc resection. Diagnoses were rendered as per currently accepted guidelines [4,5], and included leiomyoma (leio), cellular leiomyoma (CL), atypical leiomyoma (AL), smooth muscle tumor of uncertain malignant potential (STUMP), leiomyosarcoma (LMS), and endometrial stromal sarcoma (ESS). Representative images of cases diagnosed as leiomyoma (case previously published) [6], atypical leiomyoma (case #7), STUMP (case #11), and LMS (case #15) are shown in Figure 1.Case AcquisitionThe electronic medical records of the Brigham Women’s Hospital (BWH) Department of Pathology were searched for cases, both in-house and consultation, including the keywords “morcellati.