Leiomyoma

* Cotyledonoid leiomyoma or "grapelike" leiomyoma is a very rare tumor among the ever-expanding repertoire of growth variants described in benign uterine leiomyoma. We report a case of cotyledonoid leiomyoma in a 55-year-- old woman who presented with menorrhagia and uterine prolapse. A large multinodular fungating tumor adhering to the right posterolateral wall of the uterus and extending to the broad ligament was discovered at vaginal hysterectomy. With a provisional diagnosis of sarcoma, total hysterectomy and bilateral salpingo-oophorectomy were performed. Postoperatively, the patient was well with no evidence of recurrence at 14 months. Pathologic examination revealed a 10-cm, red-brown tumor that comprised multiple bulbous processes protruding over the uterine surface, in continuity with a dissecting intramyometrial component. It was composed of fascicles and nodules of bland-- looking smooth muscle cells with prominent perinodular hydropic degeneration. Coagulative necrosis, mitoses, and nuclear atypia were absent. Cotyledonoid leiomyoma apparently results from a combination of several uncommon growth patterns operating together, including subserosal growth, dissecting growth, and perinodular hydropic degeneration. Increased awareness of this grossly alarming variant of benign uterine leiomyoma can help avoid overtreatment.

(Arch Pathol Lab Med. 2002;126:210-213)

A variety of unusual growth patterns can occur in uterine leiomyomas, such as diffuse uterine leiomyomatosis, disseminated peritoneal leiomyomatosis, benign metastasizing leiomyoma, parasitic leiomyoma, intravascular leiomyomatosis, dissecting leiomyoma, and leiomyoma with perinodular hydropic degeneration.1 In 1996, Roth et al2 reported a series of 4 cases of leiomyoma characterized by remarkable extrauterine bulbous growth in continuity with a dissecting myometrial component. Because of the striking resemblance to the placenta, the term cotyledonoid dissecting leiomyoma was coined for this peculiar benign variant of leiomyoma. This type of leiomyoma had previously been reported under the designation grapelike leiomyoma.3-5 It is also called Sternberg tumor in recognition of the contribution of the late William H. Sternberg, MD, in collecting the cases from the 1940s to the 1970s.2 In this report, we describe a case of this extremely rare variant of leiomyoma and review the concept of cotyledonoid leiomyoma.

REPORT OF A CASE

A 55-year-old, previously healthy woman presented with menorrhagia and uterine prolapse. Physical examination and blood tests showed no abnormalities. This patient underwent vaginal hysterectomy. During the operation, a multinodular fungating mass was found attached to the uterus. In view of the alarming bizarre appearance, a provisional diagnosis of sarcoma was rendered, and total hysterectomy and bilateral salpingo-oophorectomy were performed instead. She was well after the operation, and there was no recurrence at the latest follow-up, 14 months after surgery.

MATERIALS AND METHODS

Hematoxylin-eosin-stained slides were prepared from paraffin blocks according to the standard protocols. Immunohistochemical staining with the labeled streptavidin-biotin peroxidase detection system was performed using the Ventana automated immunostainer (Ventana, Tucson, Ariz). The antibodies muscle-specific actin (HHF-35, 1:3, Enzo Biochem, New York, NY), desmin (D33, 1:100, Dakopatts, Glostrup, Denmark), estrogen receptor (NCL-ER-6F11, 1:20, Novocastra, Newcastle upon Tyne, United Kingdom), progesterone receptor (1A6, 1:20, Dakopatts), and CD34 (MY10, 1:40, Becton-Dickinson, San Jose, Calif) were used.

PATHOLOGIC FINDINGS

The tumor formed a large fungating mass over the right posterior wall of the uterus, extending from the level of the right cornu to the endocervix, and laterally to the right broad ligament (Figure 1, A). This "exophytic" component measured 10 x 9 x 4 cm in aggregate, but the site of attachment of the exophytic component to the uterus at the middle portion of the right posterior wall was relatively narrow, measuring 3 x 2 cm. It consisted of multiple red-brown globular nodules measuring 1 to 3.5 cm, with smaller fine nodules emerging from their surfaces (Figure 1, B). The nodules were wrapped by anastomosing networks of blood vessels, reminiscent of the cotyledons of a placenta. Some nodules were suspended by threadlike strands that contained blood vessels (Figure 1, B). The cut surfaces of the exophytic tumor component revealed firm tan-colored nodules, which were in continuity with an intrauterine component measuring 3.5 X 3 cm. The latter was a noncircumscribed mass comprising multiple small nodules separated by edematous stroma and showing nodular projections into the surrounding myometrium (Figure 1, C). The fallopian tubes and the ovaries were not involved.

Microscopically, the tumor comprised whorls or interlacing fascicles of uniform smooth muscle cells with no atypia, mitotic activity, or coagulative necrosis (Figure 2). It dissected in a sinuous pattern or in the form of nodules into the adjacent myometrium (Figure 3). Perinodular hydropic degeneration was prominent. The exophytic bulbous processes apparently resulted from prominent hydropic degeneration between smooth muscle nodules (Figure 4, A). The intervening stroma was edematous and highly vascularized. There were many congested, thick-- walled blood vessels, but intravascular growth was not found (Figure 4, B).

The tumor cells showed positive immunostaining for muscle-specific actin, desmin, estrogen receptor, and progesterone receptor. CD34 immunostaining confirmed that there was no intravascular extension of the tumor.

COMMENTS

Cotyledonoid leiomyoma is a very rare variant of uterine leiomyoma characterized by the presence of numerous bulbous protrusions over the uterus, resembling the cotyledons of a placenta. Grapelike leiomyoma apparently represents the same entity.3-5 Including the current case, to our knowledge only 11 cases have been recorded in the literature to date (Table).2-7 Fukunaga and Ushigome8 described a case of uterine leiomyoma with multinodular dissecting growth in the myometrium and extrauterine extension, but the tumor did not form bulbous processes, and therefore by definition cannot be considered a cotyledonoid leiomyoma. An example of multinodular hydropic dissecting leiomyoma reported by Roth and Reed, showed edematous bulbous processes distorting the surface of the uterus, but it was not a cotyledonoid leiomyoma, because no discrete protruding nodules were present.

The ages of the patients with cotyledonoid leiomyoma ranged from 23 to 65 years, with a median of 40 years and a mean of 40.1 years (Table). The most common presenting symptoms were abnormal uterine bleeding and pelvic mass. In all 5 cases for which the intraoperative diagnosis was recorded, a malignant neoplasm, especially leiomyosarcoma, was seriously considered.3-5 The impression of malignancy can be attributed to lack of familiarity with the alarming fungating appearance of cotyledonoid leiomyoma, the large size of the tumor (all reported cases were 10 cm or larger in maximum dimension, mean 16.6 cm), and the apparent widespread infiltrative growth with frequent extension into the pelvic cavity and broad ligament, and even into the retroperitoneal space. Nonetheless, this tumor lacks the soft consistency commonly observed in leiomyosarcomas. The histologic features of the tumor are those of a bland-looking and mitotically inactive leiomyoma, and clinical outcome has been uniformly benign.

It appears that several factors in operation together are required to produce the distinctive gross appearance of cotyledonoid leiomyoma, hence its rarity. First of all, the leiomyoma must originate close to the serosal surface for outward extension into the free space of the pelvic cavity. Practically all reported cases arose in the fundus or the posterior aspect of the cornu of the uterus; perhaps there is relatively more potential space for serosal growth over these areas. Only 1 case has shown anterior extension to the bladder peritoneum. Secondly, the leiomyoma has to exhibit dissecting growth, an uncommon growth pattern in uterine leiomyoma characterized by dissection of the myometrium at the periphery of the tumor in the form of sinuous processes, producing micronodules of swirled neoplastic smooth muscle cells within the myometrium.1 Among the 8 cases of cotyledonoid leiomyoma for which the intramural component was mentioned, 7 showed a dissecting growth pattern.2,4,6 Given the rarity of dissecting growth pattern and its nearly consistent presence in cotyledonoid leiomyoma, it appears that the bulbous serosal nodules may be viewed as a special pattern of dissecting growth beyond the confines of the uterine corpus.2 In the only example lacking an intramural dissecting component, the tumor was located at the interface between the myometrium and the serosa, thus producing exclusively exophytic growth.7 Finally, the leiomyoma has to show perinodular hydropic degeneration, another rare form of stromal change in leiomyoma characterized by accumulation of edematous fluid in the connective tissue subdividing the tumor into numerous, small, compact smooth muscle nodules.9 The hydropic stroma is typically richly vascularized and can even resemble hemangioma. This peculiar appearance can impart an erroneous impression of intravenous leiomyomatosis. It is conceivable that the poor mechanical support in the exophytic component of the tumor may lead to breakdown of the perinodular hydropic stroma, exposing the nonhydropic neoplastic smooth muscle nodules to produce exophytic nodules. In addition, the poorly supported blood vessels in the broken-down stroma are markedly congested, giving rise to the characteristic red-brown color observed in the tumor.2 The prominence of thick-walled blood vessels has led us to consider whether the tumor is derived from vessel-associated or myometrial smooth muscle. The positive immunostaining for hormone receptors supports the latter possibility.

In summary, cotyledonoid leiomyomas of the uterus apparently result from coexistence and interplay of a number of uncommon growth features, including subserosal growth, dissecting growth, and perinodular hydropic degeneration. The most important reason to recognize this unusual variant is to avoid mistaking it for a malignant neoplasm.

References

1. Roth LM, Reed RJ. Dissecting leiomyomas of the uterus other than cotyledonoid dissecting leiomyomas: a report of eight cases. Am J Surg Pathol. 1999; 23:1032-1039.

2. Roth LM, Reed Rj, Sternberg WH. Cotyledonoid dissecting leiomyoma of the uterus: the Sternberg tumor [see comments]. Am] Surg Pathol. 1996;20:14551461.

3. David MP, Homonnai TZ, Deligdish L, Loewenthal M. Grape-like leiomyomas of the uterus. Int Surg. 1975;60:238-239.

4. Payan H, Monges G, Jouve MP, Sudan N, Gamerre M. An unusual case of uterine leiomyoma: exophytic grape-like development in the pelvic peritoneum [in French]. Arch Anat Cytol Pathol. 1980;28:45-49.

5. Brand AH, Scurry JP, Planner RS, Grant PT. Grapelike leiomyoma of the uterus. Am] Obstet Gynecol. 1995;173:959-961.

6. Menolascino-Bratty F, Garcia de Barriola V, Naranjo de Gomez M, Garcia Tamayo J, Suarez JA, Hernandez Chacon AV. Cotyledonoid dissecting leiomyoma (Sternberg tumor): an unusual form of leiomyoma. Pathol Res Pract. 1999;195: 435-438.

7. Roth LM, Reed RJ. Cotyledonoid leiomyoma of the uterus: report of a case. Int J Gynecol Pathol. 2000;19:272-275.

8. Fukunaga M, Ushigome S. Dissecting leiomyoma of the uterus with extrauterine extension. Histopathology. 1998;32:160-164.

9. Clement PB, Young RH, Scully RE. Diffuse, perinodular, and other patterns of hydropic degeneration within and adjacent to uterine leiomyomas: problems in differential diagnosis. Am I Surg Pathol. 1992;16:26-32.

W. Cheuk, MBBS; John K.C. Chan, MBBS, FRCPath; John Y.S. Liu, MBBS, MRCOG

Accepted for publication July 17, 2001.

From the Departments of Pathology (Drs Cheuk and Chan) and Obstetrics and Gynecology (Dr Liu), Queen Elizabeth Hospital, Hong Kong.

Reprints: Wah Cheuk, MBBS, Department of Pathology, Queen Elizabeth Hospital, Wylie Rd, Kowloon, Hong Kong (e-mail: cheuk_wah@hotmail.com).

Copyright College of American Pathologists Feb 2002
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