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Parasitic leiomyoma

      Case note

      A 31-year-old nulliparous woman presented to the Gynaecology-Oncology service for the evaluation of progressive abdominal distension and early satiety over the preceding 2 years. Her menstrual cycles were regular with no abnormal uterine bleeding. She had no previous surgeries, and her family history was significant for breast and endometrial carcinoma. On examination, the abdomen was distended to the xiphisternum with a 40-week sized pelvi-abdominal mass without regional or supraclavicular lymphadenopathy. The cancer antigen 125 level was elevated at 430 units/mL, and computed tomography scan corroborated the presence of 2 large complex solid-cystic masses that appeared to be ovarian in origin (Figure 1).
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      Figure 1Radiology images
      Coronal (left) and sagittal (right) views from computed tomography scan demonstrating 2 heterogeneous, complex solid-cystic masses with ascites, elevation of the right hemi-diaphragm, and mass effect on the surrounding bowel. The uterus and ovaries are not well delineated from these masses.
      Dashraath. Parasitic leiomyoma. Am J Obstet Gynecol 2016.
      At laparotomy, however, the clinical suspicion of a bilateral ovarian neoplasm was quelled, because both ovaries appeared normal. Instead, a giant multilobulated abdominal mass was seen bathed in straw-colored ascites and adherent to the greater omentum via engorged, serpentine vessels (Figure 2), in keeping with a parasitic leiomyoma. The uterus, which was separate from this mass, was enlarged irregularly by subserosal leiomyomas. An infracolic omentectomy was performed, which enabled the mass to be resected en-bloc.
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      Figure 2Intraoperative findings
      A 30 cm × 30 cm × 25 cm parasitic myoma (left) swaddled in omentum with ropes of vessels plunging into the tumor. The globular uterus (right) is seen adjacent to this tumor and is enlarged by multiple subserosal fibroids—these were removed via myomectomy at the end of the surgery.
      Dashraath. Parasitic leiomyoma. Am J Obstet Gynecol 2016.
      On pathologic evaluation (Figure 3), the abdominal mass measured 30 cm × 30 cm × 25 cm in size, and the cut surface demonstrated a whorled appearance with extensive cystic degeneration. Histology was consistent with a benign, parasitic leiomyoma with myxoid and cystic changes, and there were no malignant cells seen in peritoneal fluid cytology. The patient’s postoperative course was uncomplicated.
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      Figure 3Pathology images
      Cut section of the parasitic myoma (left) illustrating a predominantly solid-cystic whorled appearance with extensive myxoid degeneration, edema and foci of infarct-type necrosis. Photomicrograph of the specimen (right) shows intercalating smooth muscle fibers with myxoid change (hematoxylin and eosin stain). There were no cytological features of malignancy.
      Dashraath. Parasitic leiomyoma. Am J Obstet Gynecol 2016.

      Comment

      Parasitic leiomyoma is a rare variant of a common gynecologic entity. It classically is defined as a pedunculated subserosal fibroid that undergoes torsion, detaches from the uterus, and sustains its growth through neovascularization from adjacent tissues.
      • Kelly H.A.
      • Cullen T.S.
      Myomata of the uterus.
      More contemporarily, it also is recognized that these monoclonal tumors may arise postoperatively after morcellation during laparoscopic myomectomy
      • Leren V.
      • Langebrekke A.
      • Qvigstad E.
      Parasitic leiomyomas after laparoscopic surgery with morcellation.
      or develop de novo after peritoneal metaplasia (resulting in diffuse peritoneal leiomyomatosis).
      • Fasih N.
      • Prasad Shanbhogue A.K.
      • Macdonald D.B.
      • et al.
      Leiomyomas beyond the uterus: unusual locations, rare manifestations.
      This case illustrates how large parasitic fibroids may masquerade as adnexal masses and preclude preoperative diagnosis. Consequently, they should be considered in the differential diagnosis of women presenting with an intra-abdominal tumor.

      Acknowledgment

      The authors thank A/Prof Gangaraju C. Raju, FRCPath, Department of Pathology, National University Hospital, Singapore for furnishing the pathology images.

      References

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