A subserosal, pedunculated, multilocular uterine leiomyoma with ovarian tumor-like morphology and histological architecture of adenomatoid tumors: a case report and review of the literature

A 47-year-old premenopausal, nulliparous Japanese woman was referred to our hospital because of an abdominal mass and a symptom of abdominal pain. She had a history of type 2 diabetes mellitus, hypertension, hyperlipidemia, and fatty liver, and she was treated for the former two conditions. No history of surgery was found. Her vital signs were unremarkable, and rebound tenderness was absent. Transvaginal ultrasonography (US) confirmed a 77 × 60 × 51-mm multilocular mass near the right side of the uterus, and ascites was also seen. Since the right ovary could not be seen, a right ovarian tumor was considered. Various tumor markers, including the carcinoembryonic antigen, cancer antigen 72–4, carbohydrate antigen 19–9, and cancer antigen 125 (CA-125) were within normal limits. Bloody ascites was obtained, but abnormal cells were not confirmed cytologically. A computed tomography (CT) scan showed that the mass was present near the uterus, and it appeared to have a heterogeneous appearance with isodensity to hypodense areas relative to the uterine myometrium (Fig. 1a). A magnetic resonance imaging (MRI) scan showed the heterogeneous mass (Fig. 1b-d), and it had a low signal intensity on T1-weighted images (T1WIs) (Fig. 1b). T2WIs (Fig. 1c) showed that the mass had high signal intensity areas, and the other portions were slightly hyperintense relative to the uterine myometrium. A fat-saturated, gadolinium-enhanced T1WI (Fig. 1d) showed that the peripheral and septum-like portions of the mass were well enhanced, and no enhancement was seen in the hyperintense portions on T2WIs. No fat component was observed. Thus, the mass was considered a multilocular cystic lesion containing fluid materials in the cavities. On CT and MRI scans, the right ovary was not visible, but a left swollen ovary was found. Thus, a right ovarian mucinous tumor was considered. Aside from the mass, a 15-mm intramural, solid, demarcated nodule was seen in the uterine body. Her abdominal pain gradually decreased; additionally, 2 weeks after the onset of abdominal pain, the mass decreased in size to 50 × 47 × 46 mm, and no ascites was seen by transvaginal US. Two months after the onset of abdominal pain, the mass slightly enlarged to 60 × 50 × 50 mm without apparent symptoms, and surgical resection was planned. One week later, sudden abdominal pain resulted in emergency surgery under the diagnosis of torsion of the pedicle of the ovarian tumor. During surgery, we found a 6-cm pedunculated, round mass connected to the uterine fundus by a 1-cm narrow stalk. The mass was red and hemorrhagic, and bloody ascites was seen; however, neither torsion of the stalk nor tumor rupture was observed. A normal right ovary was seen, and the left ovary was swollen with cystic change. Thus, a subserosal leiomyoma was considered. There were no gross features of the cotyledonoid dissecting leiomyoma, which are multiple bulbous protrusions from the uterine serosa. Extirpation of the pedunculated uterine mass and cystectomy of the left ovarian lesion were performed, and our patient was discharged 3 days postoperatively without sequelae.

Macroscopically, the formalin-fixed uterine tissue was dark and red (Fig. 2a-b), and the cut surface was solid with a cystic appearance and brownish or serous fluids. The peripheral portion of the uterine mass was particularly seen as a solid component. A leiomyoma with red degeneration was grossly considered. The cystic cavities (Fig. 2c), which were variable in size and shape, tended to be centrally accumulated in the mass. Microscopically, the cystic lesion of the left ovary was a hematoma with no neoplasia. The solid and cystic portions of the uterine mass consisted of fascicular and interlacing bland spindle cells with eosinophilic cytoplasm (Fig. 2d-f). The tumor cells had a uniform shape and scarce mitoses. Coagulation necrosis was absent, although the gross morphology of the tumor suggested red degeneration, which indicates coagulation necrosis of leiomyoma cells. Particularly, the peripheral portion of the mass demonstrated a typical feature of a leiomyoma (Fig. 2d). No apparent lining cells were seen on the cavities. In microscopically cystic lesions, thin cords of the spindle cells irregularly anastomosed to each other with serous and hemorrhagic fluids in the background (Fig. 2e-f). The anastomosing, thin, cord-like arrangement of the spindle cells appeared to be thread-like bridging strands, which is a pathological clue of adenomatoid tumors. The tumor lacked an infiltrative border and perinodal hydropic change. The pathological diagnoses included a leiomyoma and adenomatoid tumor. A perivascular epithelioid cell tumor (PEComa) could not be ruled out, because intratumoral abnormal vessels may be present. A periodic acid-Schiff stain with diastase treatment (Fig. 2g) and Alcian blue stain (Fig. 1-h) confirmed that the cystic cavities had no mucin. No iron deposition was present in the tumor according to the results of Berlin blue staining, although some hemorrhagic lesions were noted. Immunohistochemically, the spindle cells were positive for α-smooth muscle actin, desmin (Fig. 2i), the estrogen receptor, and progesterone receptor, and they were negative for cytokeratin 5 and calretinin (Fig. 2j). Although the tumor cells were partly positive for the microphthalmia transcription factor (MiTF), no immunoreactivity for the human melanoma black 45 and melan-A was seen. No dilated change in the intratumoral venous or lymphatic channels was observed in immunohistochemical sections with CD34 (Fig. 2k) or D2-40 (Fig. 2l). Thus, the mass was considered a subserosal, pedunculated leiomyoma with hydropic and cystic degeneration. Our patient had an additional intramural uterine tumor, and hysterectomy was performed to evaluate the uterine mass. Pathology results showed an intramural leiomyoma without cystic or hydropic degeneration. Neither malignancy nor adenomyosis was seen. Our patient had an unremarkable postoperative course.