We present a case of müllerian adenosarcoma arising from endometriosis of the uterosacral ligament.

She had undergone exploratory laparotomy. Laparotomy revealed a large pelvic mass that extended into the left uterosacral ligament and retroperitoneum. For intraoperative examination, two masses were received in our pathology laboratory, measuring 6x4x3cm and 7x4x2cm. Both of them had solid and cystic components. Cystic component showed papillary projections. The masses were reported as endometriosis with frozen sections.

Multiple sections were taken for routine histological examination and stained with hematoxylin and eosin. In the permanent blocks, in addition to endometriosis foci, benign appearing müllerian type glands associated with sarcomatous stroma that formed surface papillae (leaflike pattern) were noticed (Figures 1 and 2). Sarcomatous component displayed mild nuclear atypia and mitotic activity averaging 3 mitoses per 10 HPF (Figure 3). Stromal cuffing of the glands was noted focally. These findings showed that the tumor was a müllerian adenosarcoma which was closely related to endometriosis. Immunohistochemically, the tumor had a high proliferation index with Ki67 (Figure 4).

Fig 1: Typical leaf-like pattern in adenosarcoma

Fig 2: Endometriosis associated with the adenosarcoma

Fig 3: Stromal atypia and mitosis

Fig 4: The labelling index for Ki 67 is increased up to 10% stromal component

External radiotherapy was decided for the patient, but she refused adjuvant therapy.

Müllerian adenosarcoma arising from the extraovarian sites have been described[2,3,5-9]. To our knowledge, this is the first case of adenosarcoma arising from endometriosis of the uterosacral ligament in the literature.

The histogenesis of the extrauteine müllerian adenosarcoma is unclear. It may arise from a focus of endometriosis as in this case. Müllerian adenosarcomas arising in endometriosis can be incompletely diagnosed as endometriosis, especially during an intraoperative consultation.

Clement and Scully[10] have recommended that, adenosarcoma can be diagnosed when one or more of the following criteria are present: 1) stromal mitotic count of two or more per 10 HPF, 2) marked stromal cellularity, 3) more than a mild degree of stromal atypia.

Extrauterine müllerian adenosarcomas occur in younger women and are more aggressive than uterine counterparts[7].

The main reason that patients with ovarian adenosarcomas have poorer prognosis than those with uterine sarcomas is probably related to the location of the tumors with respect to the abdominal cavity and the lack of an anatomic barrier to spread.

Surgery is the mainstay of treatment. Müllerian adenosarcomas in general can be expected to recur or metastasize locally. In our case, external radiotherapy was decided but she refused adjuvant therapy. The patient is free of tumor one year postoperatively.

In conclusion, although it's rare, malignant degeneration to adenosarcoma in endometriosis cases should be kept in mind.

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8) Dincer AD, Timmins P, Pietrocola D, et al. Primary peritoneal mullerian adenosarcoma with sarcomatous overgrowth associated with endometriosis: a case report. Int J Gynecol Pathol 2002;21(1):65-8.

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