["Benign metastasizing leiomyoma"? A case report without evidence for unbalanced cytogenetic aberrations]

There are rare cases of histologically benign appearing uterine leiomyomas with subsequent development of multifocal extrauterine smooth muscle tumors, most often located in the lung. It remains unclear whether this evolves from a morphological innocent appearing low grade sarcoma or from proliferation of multifocal but autochtonous cellular foci. Frequently, and in part recurrent karyotypic abnormalities were described for leiomyomas and leiomyosarcomas. Thus, we looked for imbalanced genetic aberrations in a case of a "benign metastasizing leiomyoma" by means of comparative genomic hybridisation (CGH). A 46-year-old female developed multiple bilateral lung nodules 4 years after hysterectomy. Fine needle biopsy of one nodule and subsequent resection of three lung nodules were performed. These and the hysterectomy specimen were investigated by histology, immunohistochemistry and CGH. Revision of the hysterectomy specimen revealed multiple leiomyomas without any evidence for malignancy. Lung nodules were composed of benign appearing smooth muscle cells with epithelial lined cleft-like spaces. Leiomyomata of the uterus and the lung showed a reactivity against actin, desmin, estrogen- and progesteron receptor antigens. DNA analysis by CGH revealed a normal karyotype without evidence for an imbalanced loss or gain of DNA. Recurrent cytogenetic alterations are common in uterine leiomyomas, most often del (7)(q11.2-22q31-32) and t(12;14)(q14-15; q23-24). Leiomyosarcomas display diverse karyotypic abnormalities, most often involving chromosomes 1, 7, 13 and 14. Thus, the missing karyotypic imbalance in the presented case favors a pathogenesis which is different from usual leiomyomas as well as leiomyosarcomas.