Uterine leiomyomas are benign tumors, present in 20% to 30% of women, with clinical manifestations in women more than 35 years of age.6,7
These tumors are composed mainly of smooth muscle cells and contain varying amounts of fibrous connective tissue.8
Parasitic leiomyomas are rare complications of endoscopic surgery when myoma tissues are removed through a minimal incision after fragmentation. Most leiomyomas regress after menopause. A calcified parasitic leiomyoma in a postmenopausal woman is extremely rare; in such cases it is more difficult to predict the clinical symptoms and physical findings. In most parasitic leiomyomas reported, there was a previous history of a myomectomy and there were multiple lesions; however, in our case the patients did not have prior surgery and had a single leiomyoma. In addition, the patients had no prior reported complaints of myoma-related symptoms.
Leiomyomas are rarely found in postmenopausal women because their growth is thought to be estrogen dependent. However, there are a few reported cases of leiomyoma growth in postmenopausal women.3,9
Kawamura et al9
suggested that other estrogens or growth factors, such as estrone, insulin-like growth factors (IGF), or epidermal growth factors (EGF), might play a role in the growth of leiomyomas in postmenopausal women. Lumsden et al10
and Vollenhoven et al11
suggested that an association of polypeptide growth factors, such as platelet derived growth factors (PDGF), transforming growth factors, and vascular endothelial growth factors (VEGF), stimulated the growth of leiomyomas. Many of these growth factors are overexpressed in leiomyomas and either increase smooth muscle proliferation (TGF – transforming growth factor, FGF – fibroblast growth factors) or DNA synthesis (EGF, PDGF), stimulate synthesis of extracellular matrix (TGF-β), and promote mitogenesis (TGF-β, EGF, IGF, prolactin), or angiogenesis (FGF, VEGF).12
If a postmenopausal woman is obese, peripheral conversion of adrenal derived androstenedione to estrone by aromatization of fat might stimulate the growth of leiomyomas. In the present case, estrone or growth factors, or both, might have played a role in the growth of the leiomyoma.
Occasionally, pedunculated subserosal leiomyomas can be twisted on the uterine pedicle, and become detached in the peritoneal cavity. Such leiomyomas are referred to as “parasitic leiomyomas”; this tumor survives by revascularization from adjacent structures.8
However, sometimes the tumor can adhere to the surrounding structures. The initial pedunculated fibroid likely develops premenopausally, whereas the parasitic leiomyoma may become clinically evident either before or after menopause.13
In the present case, on laparoscopic examination, the leiomyoma was found in the anterior pouch of the pelvic cavity, just above the bladder, separate from the uterus. Therefore, it was classified as a parasitic leiomyoma.
As leiomyomas enlarge, they may outgrow their blood supply, resulting in various types of degeneration: hyaline or myxoid degeneration, calcification, cystic degeneration, or red degeneration.14
In general, hyaline degeneration is the most common (63%) form of degeneration, while the others occur less frequently, such as myxomatous changes (13%), calcification (8%), mucoid changes (6%), cystic degeneration (4%), red degeneration (3%), and fatty changes (3%).15
The finding of a calcified leiomyoma is more common in postmenopausal woman.16
Our case was diagnosed as a common leiomyoma that presented with hyaline degeneration and dystrophic calcification. The exposed surface of the specimen consists of many irregular small fragments of soft tissue with skeletal muscle, adipose tissue, and bony fragments. In cases with hyaline degeneration, the cut surface of a hyalinized area is smooth and homogeneous and does not show the typical whorl-like pattern. Over time, with a diminishing blood supply and ischemic tissue necrosis, calcium phosphates and carbonates are deposited in the leiomyoma. The calcium is deposited in varying amounts, when it is deposited in the periphery, resembling a calcified cyst. Other calcified leiomyomas show an irregular or diffuse distribution of calcium.
In our case, the pedunculated leiomyoma might be thought to be coiled on its uterine pedicle. Over time, the blood supply within the myoma might decrease, and the tissue becomes ischemic. Calcium is deposited in the peripheral portion of the leiomyoma. As the degenerative changes progress, the leiomyoma may become solidly calcified. The leiomyoma may separate completely from the uterus and develop an alternative blood supply from another source, such as omentum and adipose tissue.
Few reports have been published on the development of a parasitic leiomyoma4,5,17,18
and disseminated peritoneal leiomyomatosis19
after laparoscopic myomectomy using a morcellator. Paul and Koshy4
reported laparoscopic removal of multiple parasitic leiomyomas in a woman who had a previous laparoscopic myomectomy. The leiomyomas were found at the previous port site, the fundus of the uterus and right paracolic gutter. Another case reported by Moon et al5
describes a parasitic leiomyoma of the abdominal wall after laparoscopic myomectomy; this patient also had a history of a morcellator used in a prior myomectomy. Another report discussed implantation of retained fragments after the use of morcellation during laparoscopic surgery.17
Laparoscopic excision is the treatment of choice. The excision retrieval of the leiomyoma was achieved using an endobag instead of a morcellator in our case. The endobag was pushed toward the umbilical port site, and the mass was removed in fragments by cutting it with a knife. The technique of morcellation was introduced to laparoscopic myomectomy in the mid 1990s; it improved results and reduced blood loss and the complication rate with large leiomyomas.20
However, the risk of incomplete removal and remnants has increased with the use of the morcellator due to the multiple small fragments resulting from the procedure.