A critical review of uterine leiomyoma with subsequent recurrence or metastasis: A multicenter study of 62 cases

Aim: Histopathologic diagnosis of a subset of uterine smooth muscle tumors
is challenging. We report a critical review regarding the
clinicopathological point of view of 62 cases of subsequently recurred or
metastasized leiomyoma. Methods: Medical records and glass slides of 62
cases of uterine smooth muscle tumor diagnosed as leiomyoma, which
subsequently recurred or metastasized, were critically reviewed by
pathologists specializing in gynecologic pathology and oncology. 
Results: In 47 (75.8%) of 62 cases, the diagnosis of leiomyoma was
confirmed, including 11 intravascular leiomyomatosis (IVL) and benign
metastasizing leiomyoma (BML). In 29 cases (46.8%) laparoscopic surgery
was performed, of which morcellator without a bag was employed in 23
cases. Fifteen cases (24.2%) appeared to be underestimated and were
re-classified as smooth muscle tumor of uncertain malignant potential
(STUMP), leiomyosarcoma, or other malignant mesenchymal tumors.
Recurrences in 7 cases (11.3%) were interpreted to be a malignant
transformation, and one Smooth muscle tumor of uncertain malignant
potential (STUMP) recurred as STUMP.  Conclusion: The recurrence
or metastasis in cases of “leiomyoma” is attributed to iatrogenic or
under-evaluation of primary tumors, although a subset of cases is a rare
example of biological progression.