| The leiomyoma of uterus is a common neoplasm in women, its incidence ranging from 25% to 77%. In some cases, its nature is uncertain. Rarely, some histologically benign tumors may show local aggressiveness or even metastasis to distant organs such as lung. This tumor is often composed of two or more nodules, known as multiple uterine leiomyomas. different nodules in a single case were considered independent In the study, ckxialhy status of uterine leiomyoma was described using an assay based on the random inactivation of X chromosome and the polymorphism in female somatic cells at the phosphogrycerate kinase (PGK) locus, and the relationship among different tumor nodules in multiple cases was reevaluatedThe following tests were performed: (1) genomic DMA was extracted from fresh neoplastic tissue and the peritumorous normal smooth muscle tissue as a control; (2) the reliability of the assay was assessed considering the patching in uterine smooth muscle tissue; (3) multiple leiomyomas were examined for their mhotic figures.Thirty-six of the 121 uterine leiomyomas presented polymorphism at the Bst XI recognition site. Loss of the X-chromosome inactivation mosiacism was observed in all the tumor nodules from 32 cases examined In a multi-nodular leiomyosarcoma, 7 apparently independ nodules presented the same PGK allele inactivation pattern, demonstrating their unicellular origia Among the multiple cases, a same inactivated allele was found in all tumor nodules (10/18) or in most modules (2/18X indicating the same clonal origia Numbers of nodules may play a role in the difference, but no evidence was found to show their relevance with mrtotic index. Therefore, multiple utenne leiomyomas may be subtyped into fully independent and aggressive types, as well as a mixed type of both.In order to exclude the interference to the assay from tissue patching, imbalance of the two inactivated PGK alleles was also analyzed in six cases using pentumorous smooth muscle tissue of different sizes. The detection was performed using me smooth muscle tissue sheets as thick as 1.0mm, with the measuring areas ranging from l.Oxl.O mm2 to 10.0x10.0 mm2. For the tissue areas sizing as 1 .Ox 1.0 mm2,2.0x2.0 mm2,3.0x3.0 mm2, lose of X chromosome inactivation mosiacism was found in 28% (25/89), 19% (8/42) and 14% (6/42) of samples examined, respectively. No marked change was observed in the samples as large as 5.0x5.0 mm2 (42) and 10.0x10.0 mm2 (6) after me pretreatment with Hpa II. Therefore, the average diameter of patching in uterine smooth muscle tissue should be far smaller than 5 mm, meaning that patching would not be a problem and the clonalhy analysis would be reliable, if the examined size reaches 5.0 x 5.0 mm2 as conducted in this study. When the area of the samples as small as 3X3 mm2, attention should be paid to the interference by tissue patching. It remains unknown whether the patching size is associated with development of the smooth muscle neoplasms. |
