Atypical Polypoid Adenomyoma

Background

This is a rare and benign tumor that may be clinically and histologically mistaken for a malignancy.

Outline

Disease Associations
Pathogenesis
Laboratory/Radiologic/Other Diagnostic Testing
Gross Appearance and Clinical Variants
Histopathological Features and Variants
Special Stains/Immunohistochemistry/Electron Microscopy
Differential Diagnosis
Prognosis and Treatment
Commonly Used Terms

DISEASE ASSOCIATIONS CHARACTERIZATION

Atypical polypoid adenomyoma of the uterus associated with Turner's syndrome. A report of three cases, including a review of "estrogen-associated" endometrial neoplasms and neoplasms associated with Turner's syndrome.

Clement PB, Young RH.

Department of Pathology, Vancouver General Hospital, British Columbia, Canada.

Int J Gynecol Pathol 1987;6(2):104-13 Abstract quote

The clinical and pathological features of three atypical polypoid adenomyomas of the uterus that were associated with Turner's syndrome are described.

The patients, at least two of whom had been on long-term exogenous estrogens, were in their third decade and presented with abnormal vaginal bleeding. In two cases an exophytic mass protruded through the external os and clinically suggested a malignant tumor. The histological (and in one case, the ultrastructural) findings were similar to those of previously described cases of atypical polypoid adenomyoma. The clinical findings in these cases suggest that some atypical polypoid adenomyomas may be a complication of prolonged estrogenic stimulation.

The association between Turner's syndrome and other gynecological neoplasms is reviewed.

Peritoneal keratin granulomas with carcinomas of endometrium and ovary and atypical polypoid adenomyoma of endometrium. A clinicopathological analysis of 22 cases.

Kim KR, Scully RE.

Department of Pathology, Harvard Medical School, Boston, Massachusetts

Am J Surg Pathol 1990 Oct;14(10):925-32 Abstract quote

Twenty-two cases of keratin granulomas of the peritoneum associated with endometrioid adenocarcinoma with squamous differentiation of the endometrium, the ovary, or both, and with an atypical polypoid adenomyoma of the endometrium were reviewed.

Follow-up data were available in 18 cases. Twelve patients were well and disease free 13 months to 15.2 years postoperatively; one patient died of unrelated disease 21 years postoperatively; three patients were tumor free with a short duration of follow-up; one patient, who had a stage Ic ovarian tumor, died of pulmonary embolism during the treatment of recurrent tumor 1 year after operation; and a final patient, who had been followed for 3 months after operation for stage IV disease, was alive with residual tumor. At least six patients with stage I carcinomas were treated with postoperative irradiation because the granulomas had raised a suspicion of advanced disease.

Follow-up data on the patients in this series suggest that peritoneal keratin granulomas have no prognostic significance and should be distinguished from viable tumor implants on microscopic examination.

Atypical polypoid adenomyoma of the endometrium associated with adenomyomatosis and adenocarcinoma.

Lee KR.

Department of Pathology, University of Vermont, College of Medicine, Burlington 05405.

Gynecol Oncol 1993 Dec;51(3):416-8 Abstract quote

A case in which the uterus from a 44-year-old woman contained an atypical polypoid adenomyoma of the endometrium with adjacent adenomyomatosis in which there were focal areas of adenocarcinoma is described.

This unique combination has not been previously reported. Possible histogenesis is discussed.

Uterine atypical polypoid adenomyoma and ovarian endometrioid carcinoma: metastatic disease or dual primaries?

Duggan MA, Rowlands C, Kneafsey PD, Nation JG, Stuart GC.

Department of Pathology, Foothills Hospital, Calgary, Alberta, Canada

Int J Gynecol Pathol 1995 Jan;14(1):81-6 Abstract quote

Atypical polypoid adenomyoma (APA) is an uncommon uterine tumor that rarely metastasizes, although it closely resembles a well-differentiated endometrioid carcinoma.

A 37-year-old woman with a history of pelvic endometriosis and oral contraceptive use developed an APA and later presented with bilateral ovarian endometrioid carcinomas. DNA ploidy analysis and human papilloma virus (HPV) typing of the APA and ovarian carcinomas were performed to characterize the primary or metastatic nature of the tumors. Both tumors were aneuploid. The APA had a DNA index of 1.53, compared with 1.19 for the ovarian carcinoma. The APA contained HPV 18, and the ovarian carcinoma a mixed infection of HPV 6, 11, 16, and 18, with types 6 and 11 predominating. These differences in DNA index and HPV type supported the autonomous nature of the APA and the ovarian carcinomas.

The report affirms the benign outcome of APA, highlights its complication by a second malignancy, and suggests an etiological role for endometriosis, steroid hormones, and possibly the HPV in the formation of one or both tumors.

Atypical polypoid adenomyoma in a patient with hyperprolactinemia.

Nasu K, Miyazaki T, Takai N, Miyakawa I.

Department of Obstetrics and Gynecology, Oita Medical University, Oita, Japan.

Int J Gynecol Cancer 2001 Jul-Aug;11(4):326-8 Abstract quote

We report a case of an atypical polypoid adenomyoma in a patient with hyperprolactinemia.

A 23-year-old Japanese woman was admitted complaining of atypical genital bleeding. Specula examination revealed a walnut-size polypoid mass extruding from the cervix. The patient was oligomenorrheac, and endocrine analysis showed hyperprolactinemia. Transvaginal ultrasonography and magnetic resonance imaging revealed an endometrial polypoid mass (4 x 3 x 3 cm) arising from the lower segment of the uterine corpus. The pathologic diagnosis of the tumor after polypectomy was atypical polypoid adenomyoma.

It is suggested that ovarian dysfunction caused by hyperprolactinemia may be involved in the pathogenesis of atypical polypoid adenomyoma in the present case.

PATHOGENESIS CHARACTERIZATION

Atypical polypoid adenomyomas of the uterus.

Fukunaga M, Endo Y, Ushigome S, Ishikawa E.

Department of Pathology, Jikei University School of Medicine, Tokyo, Japan.

Histopathology 1995 Jul;27(1):35-42 Abstract quote

We performed a clinicopathological immunohistochemical, ultrastructural, and flow cytometric study on six cases of atypical polypoid adenomyoma of the uterus including one with an adenocarcinoma within it.

The tumours occurred in nulliparous women aged 22-48 years (average, 33.0 years); three arose in the uterine corpus, and three in the endocervix. Histologically, they were composed of endometrial glands admixed with a stromal component of interlacing bundles of smooth muscle cells. The glands exhibited varying degrees of architectural and cytological atypia. Most of the stromal cells showed strong staining for HHF35, alpha-smooth muscle actin, and vimentin, and some cells contained desmin.

Electronmicroscopy, in one case, confirmed the presence of a well-differentiated smooth muscle component. The stromal component may arise as a result of extensive metaplasia of endometrial stromal cells. Uninvolved endometrium showed ciliated cell metaplasia in three patients, and atypical complex hyperplasia in two. One patient had a well-differentiated adenocarcinoma of endometrioid type arising in an endocervical atypical polypoid adenomyoma. All tumours had a diploid DNA content and relatively small S phase fraction (average, 6.23%).

The follow-up periods ranged from 4 to 42 months (average, 13.5 months), and all patients were alive and well. Although the histogenesis of atypical polypoid adenomyoma of the uterus remains uncertain, it is suggested that it may arise because of oestrogen-related factors.

LABORATORY/RADIOLOGIC/
OTHER TESTS
CHARACTERIZATION

RADIOLOGIC

MR imaging of atypical polypoid adenomyoma.

Yamashita Y, Torashima M, Hatanaka Y, Takahashi M, Fukumatsu K, Tanaka N, Miyazaki K, Okamura H.

Department of Radiology, Kumamoto University School of Medicine, Japan.

Comput Med Imaging Graph 1995 Jul-Aug;19(4):351-5 Abstract quote

The magnetic resonance (MR) appearances of three cases of atypical polypoid adenomyoma are reported. The signal intensity of the tumor was similar to that of adenomyosis on T2-weighted MR Imaging (MRI). On contrast-enhanced study, irregular enhancement was seen in hyperintense areas on T2-weighted images.

Atypical polypoid adenomyoma can be characterized as a hypointense polypoid mass with hyperintense foci on T2-weighted MR images, resembling the appearance of adenomyosis.

GROSS APPEARANCE/
CLINICAL VARIANTS CHARACTERIZATION

GENERAL

VARIANTS

Atypical polypoid adenomyoma of the uterus in a very old woman. Report of a case with immunohistochemical characterization of its stromal components and proliferative status.

Kuwashima Y, Uehara T, Kurosumi M, Kishi K, Ohno H, Maruyama M, Takayama S.

Department of Pathology, Saitama Cancer Center, Japan.

Eur J Gynaecol Oncol 1995;16(2):115-9 Abstract quote

A case of atypical polypoid adenomyoma (APA) of the uterus in an 81-year-old patient is reported. The tumor arose in the uterine fundus as a polypoid mass and measured 9 cm in its longest diameter. Its histological appearance was similar to that of the reported cases, i.e. presence of atypical endometrial glands and a cellular smooth muscle stroma. However, the patient's age was extremely advanced, since APA has predominantly been reported to arise in premenopausal women. APA has been suggested as being related to prolonged estrogenic stimulation. But the fact that in this case the uninvolved endometrium was absolutely atrophic, negated this possibility.

Immunohistochemistry for alpha smooth muscle actin was positive diffusely in the stroma. The proliferative status of the neoplastic glands was assessed by immunostaining for Ki-67 antigen. About 30% of the glands contained Ki-67 positive nuclei, and about 3% of the nuclei were positive in the glands.

These figures are far below those of the usual endometrial adenocarcinoma, strongly suggesting that the APA was benign in nature.

HISTOLOGICAL TYPES CHARACTERIZATION

GENERAL

Atypical polypoid adenomyoma of the uterus. A report of 27 cases.

Young RH, Treger T, Scully RE.

Am J Clin Pathol 1986 Aug;86(2):139-45 Abstract quote

Twenty-seven atypical polypoid adenomyomas of the uterus were reviewed.

The tumors occurred in women ages 21-53 (average 39.7) years old, who presented with abnormal uterine bleeding in most cases. Two of the patients had Turner's syndrome. The adenomyomas most frequently involved the lower uterine segment, measured up to 6 (average 1.9) cm in greatest dimension, and were characteristically polypoid and well circumscribed. Microscopic examination disclosed endometrial glands with varying degrees of hyperplasia and atypicality up to the appearance of carcinoma in situ within neoplastic smooth muscle. Squamous differentiation was common within the glands; the smooth muscle occasionally was atypical. Follow-up data suggested that the lesion is benign, although it persisted in two patients treated by curettage alone.

Atypical polypoid adenomyomas should be distinguished from endometrial carcinomas and other malignant uterine neoplasms with which they are often confused, particularly in curettage specimens.

Atypical polypoid adenomyoma--clinical histological and immunocytochemical findings.

Rollason TP, Redman CW.

Department of Pathology, Medical School, University of Birmingham, Edgbaston, England.

Eur J Gynaecol Oncol 1988;9(6):444-51 Abstract quote

The clinico-pathological features of four examples of a distinctive benign uterine neoplasm are presented which has previously been titled atypical adenomyoma.

The patients were all nulliparous and premenopausal. All presented with menstrual disturbances. No tumour has recurred after hysterectomy (follow-up between 10 years and 10 months). All tumours arose from the corpus, three were localised lower segment polyps, one a diffuse polypoid involvement of the endometrium. Histologically all of the tumours showed very similar appearances with closely packed, regular, tubular glands lined by low columnar epithelium, resembling most closely basal endometrial glands and surrounded by benign connective tissue which by simple tinctorial methods appeared to be largely smooth muscle. No heterologous components were seen. In two cases squamous metaplasia was extensive, in one microcalcification was present.

The histological appearances favour a type of benign mixed Mullerian tumour but the appearances are not typical of Mullerian adenofibroma. Immunocytochemistry performed on 3 cases confirmed that the stroma was in large part smooth muscle, though much of the stroma stained only weakly with monoclonal antidesmin antibody.

Atypical polypoid adenomyofibromas (atypical polypoid adenomyomas) of the uterus. A clinicopathologic study of 55 cases.

Longacre TA, Chung MH, Rouse RV, Hendrickson MR.

Division of Surgical Pathology, Stanford University Medical Center, CA 94305, USA.

Am J Surg Pathol 1996 Jan;20(1):1-20 Abstract quote

We present the clinicopathological and immunohistochemical features of 55 atypical polypoid adenomyofibromas, a definitional expansion of an entity previously reported as "atypical polypoid adenomyoma" (APA) of the uterus.

Patients ranged in age from 25 to 73 (mean, 39.9) years. All but two of the patients were premenopausal, and 14 were undergoing evaluation for infertility.

Histologically, the lesions featured a biphasic proliferation of architecturally complex and cytologically atypical endometrial glands within a myofibromatous stroma. The histologic pattern ranged from widely separated and loosely clustered irregular but branched glands embedded in broad zones of cellular myofibromatous stroma to those possessing crowded, markedly complex, branching glands separated by sparse intersecting fascicles of fibromuscular tissue. The stroma in all cases was actin or desmin positive or both. Morular/squamous metaplasia was present in all but two cases and florid in most. All cases exhibited architecturally complex glands, and in 25 cases the architectural complexity was indistinguishable from that of well-differentiated endometrial adenocarcinoma, as we have defined it; that is, they had a high architectural index.

Twenty-nine patients were initially treated with polypectomy or curettage followed by hormonal therapy; persistent or recurrent APA developed in 45% of the patients in this group (33% with low architectural index vs. 60% with high architectural index). Five patients had successful pregnancies despite persistent disease. Superficial myoinvasion was identified in the hysterectomy specimen in two of 12 APAs with a high architectural index but not in 21 APAs with a low architectural index. All patients are alive and well 1 to 112 months after diagnosis (mean, 25.2 months). On the basis of this study, we propose that APAs with markedly complex glands (high architectural index) be designated "atypical polypoid adenomyofibromas of low malignant potential" (APA-LMP) to emphasize the potential risk for myometrial invasion.

A treatment program featuring local excision accompanied by close follow-up is warranted for APA despite the presence of recurrent or persistent disease. Patients with APA-LMP may also, in selected cases, be managed with less than hysterectomy, although (as with the usual well-differentiated carcinoma) there is a small but definite risk associated with this approach.

VARIANTS

SPECIAL STAINS/IMMUNOPEROXIDASE/
OTHER CHARACTERIZATION

IMMUNOPEROXIDASE

Atypical polypoid adenomyoma of the uterus. An immunohistochemical study of a case.

Di Palma S, Santini D, Martinelli G.

Divisione di Anatomia Patologica e Citologia, Istituto Nazionale Tumori, Milano, Italy.

Tumori 1989 Jun 30;75(3):292-5 Abstract quote

We studied one case of atypical polypoid adenomyoma of the uerus immunohistochemically using antisera against keratins, vinentin, S-100 protein, desmin and actin. The stromal cells were reactive with anti-actin and antidesmin antibodies suggesting a muscular phenotype and confirming previous ultrastructural data.

Immunohistochemical investigations have proved to be useful in differential diagnosis of APA with invasive adenocarcinoma, adenosarcoma and adenofibroma of the endometrium.

Atypical polypoid adenomyofibroma (APA) versus well-differentiated endometrial carcinoma with prominent stromal matrix: an immunohistochemical study.

Soslow RA, Chung MH, Rouse RV, Hendrickson MR, Longacre TA.

Division of Surgical Pathology, Stanford University Medical Center, California 94305, USA.

Int J Gynecol Pathol 1996 Jul;15(3):209-16 Abstract quote

It can be extremely difficult in some cases to distinguish atypical polypoid adenomyomas (APAs) from invasive adenocarcinoma in an endometrial curettage or biopsy specimen.

In order to determine if immunophenotypic features can be exploited to differentiate between these two entities in problematic cases, a series of APAs and myoinvasive well-differentiated endometrial carcinomas (WDCAs) were studied with a panel of standard immunohistochemical markers.

All 23 APAs had stromal smooth muscle actin (SMA) reactivity, 12 of 23 had variable degrees of stromal desmin reactivity, and nine of 22 had CD34-positive stromal cells. All epithelial components of the APAs were cytokeratin (AE1 and CAM5.2) positive, whereas 22 of 23 were positive for estrogen receptor (ER) and progesterone receptor (PR). Among the 10 myoinvasive WDCAs, all contained at least some SMA-positive stromal cells, seven of 10 desmin-positive stromal cells, and four of eight CD34-positive stromal cells. All carcinomas studied demonstrated CAM5.2 and PR-positive epithelia; nine of 10 were ER positive.

We conclude that the immunophenotype of APAs does not differ significantly from well-differentiated endometrial adenocarcinoma and that immunophenotyping is of little value in distinguishing APA from carcinoma. Because the stroma in APAs histologically and immunophenotypically more closely resembles a hybrid myofibromatous stroma, we prefer to refer to these lesions with the modified designation "atypical polypoid adenomyofibroma," although "APA" may be retained for clinical use.

ELECTRON MICROSCOPY

Atypical polypoid adenomyoma: a case report with ultrastructural examination.

Delprado WJ, Stevens SM, Baird PJ.

Pathology 1985 Jul;17(3):522-5 Abstract quote

A case of atypical polypoid adenomyoma occurring in a 40 yr-old female is reported. The lesion was composed of irregular glands lined by atypical epithelium lying in a spindle cell stroma containing smooth muscle cells. The mitotic count of the stroma was less than 1 per 10 high power fields. Squamous metaplasia was present in the glandular elements.

Ultrastructural examination of the stroma confirmed the presence of smooth muscle cells. The lesion is compared with similar cases previously reported.

The differential diagnosis is considered, including endometrial adenocarcinoma, adenomyosis, endometrial polyps and mixed Mullerian tumours. Atypical polypoid adenomyoma is a benign lesion, and conservative management is recommended.

DIFFERENTIAL DIAGNOSIS KEY DIFFERENTIATING FEATURES

Uterine adenomyomas excluding atypical polypoid adenomyomas and adenomyomas of endocervical type: a clinicopathologic study of 30 cases of an underemphasized lesion that may cause diagnostic problems with brief consideration of adenomyomas of other female genital tract sites.

Gilks CB, Clement PB, Hart WR, Young RH.

Department of Pathology, Vancouver Hospital & Health Sciences Centre, BC, Canada.

Int J Gynecol Pathol 2000 Jul;19(3):195-205 Abstract quote

We report 30 uterine tumors composed of an admixture of endometrioid glands, endometrioid stroma, and smooth muscle that lacked the characteristic features of atypical polypoid adenomyoma.

The patients ranged from 26 to 64 (median 47) years of age. The usual presenting symptom was abnormal vaginal bleeding, which was "massive" in two patients. Six patients were treated by polypectomy only, with hysterectomy performed in the remainder. Twenty-seven adenomyomas were in the corpus (22 submucosal, two mural, and three subserosal) and three in the cervix. The subserosal and submucosal examples were polypoid. The tumors were 0.3 to 17 cm in greatest dimension, and firm with cystic areas often present on sectioning. Focal hemorrhage was described in five cases.

On microscopic examination, the tumors were composed of glands and cysts lined by endometrial-type epithelium separated by endometrial stroma and smooth muscle, with smooth muscle predominating. Minor foci of tubal-type epithelium (14 cases), mucinous endocervical-type epithelium (2 cases), and squamous epithelium (1 case) were present. The smooth muscle component was cellular in three cases and contained occasional bizarre nuclei in three cases. The epithelial cells were uniformly bland. No mitotic activity was observed in the epithelial or mesenchymal elements in 20 cases. In the remainder, up to 5 mitotic figures/10 high-power fields were observed in the epithelium (3 cases), the stroma and smooth muscle (3 cases), or both compartments (4 cases).

Follow-up in 14 cases revealed no recurrence or extrauterine spread in any case. A diagnosis of adenocarcinoma or adenosarcoma was entertained by the submitting pathologist in five of 14 consultation cases.

Adenomyomas are unusual benign uterine tumors that can be misdiagnosed, in part, because the lesion has not often received attention in the literature. The most realistic considerations in the differential diagnosis are atypical polypoid adenomyoma and adenosarcoma. The former, by definition, has epithelial atypia and the latter a malignant (usually low grade) stromal component with typically absent or inconspicuous smooth muscle. Distinction of adenomyoma from adenosarcoma may have significant therapeutic implications, particularly in young women.

PROGNOSIS AND TREATMENT CHARACTERIZATION

PROGNOSTIC FACTORS

Coexistent atypical polypoid adenomyoma and endometrial adenocarcinoma.

Mittal KR, Peng XC, Wallach RC, Demopoulos RI.

Department of Pathology, New York University Medical Center, NY, USA.

Hum Pathol 1995 May;26(5):574-6 Abstract quote

Atypical polypoid adenomyoma (APA) is a rare entity that is believed to follow a benign course. We report a case of APA with coexistent endometrial adenocarcinoma.

The example raises the possibility that APA may progress to endometrial adenocarcinoma in some cases.

Two cases of endometrial adenocarcinoma arising from atypical polypoid adenomyoma.

Sugiyama T, Ohta S, Nishida T, Okura N, Tanabe K, Yakushiji M.

Department of Obstetrics and Gynecology, Kurume University School of Medicine, 67 Asahi-machi, Kurume City, 830-0011, Japan.

Gynecol Oncol 1998 Oct;71(1):141-4 Abstract quote

Atypical polypoid adenomyoma (APA) most frequently presents as an endometrial polyp in premenopausal women and is believed to follow a benign course. In hysterectomy specimens from postmenopausal Japanease women, the endometrium contained an APA with an area of endometrial adenocarcinoma.

A convincing transition zone between the APA and the adenocarcinoma was seen in our cases, suggesting that APA may develop into endometrial adenocarcinoma in postmenopausal women.

TREATMENT Simple excision or removal

Rosai J. Ackerman's Surgical Pathology. Eight Edition. Mosby 1996.
Sternberg S. Diagnostic Surgical Pathology. Third Edition. Lipincott Williams and Wilkins 1999.

Commonly Used Terms

Uterus

Last Updated 12/21/2001

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HISTOLOGICAL TYPES	CHARACTERIZATION
GENERAL
Atypical polypoid adenomyoma of the uterus. A report of 27 cases. Young RH, Treger T, Scully RE.	Am J Clin Pathol 1986 Aug;86(2):139-45 Abstract quote Twenty-seven atypical polypoid adenomyomas of the uterus were reviewed. The tumors occurred in women ages 21-53 (average 39.7) years old, who presented with abnormal uterine bleeding in most cases. Two of the patients had Turner's syndrome. The adenomyomas most frequently involved the lower uterine segment, measured up to 6 (average 1.9) cm in greatest dimension, and were characteristically polypoid and well circumscribed. Microscopic examination disclosed endometrial glands with varying degrees of hyperplasia and atypicality up to the appearance of carcinoma in situ within neoplastic smooth muscle. Squamous differentiation was common within the glands; the smooth muscle occasionally was atypical. Follow-up data suggested that the lesion is benign, although it persisted in two patients treated by curettage alone. Atypical polypoid adenomyomas should be distinguished from endometrial carcinomas and other malignant uterine neoplasms with which they are often confused, particularly in curettage specimens.
Atypical polypoid adenomyoma--clinical histological and immunocytochemical findings. Rollason TP, Redman CW. Department of Pathology, Medical School, University of Birmingham, Edgbaston, England.	Eur J Gynaecol Oncol 1988;9(6):444-51 Abstract quote The clinico-pathological features of four examples of a distinctive benign uterine neoplasm are presented which has previously been titled atypical adenomyoma. The patients were all nulliparous and premenopausal. All presented with menstrual disturbances. No tumour has recurred after hysterectomy (follow-up between 10 years and 10 months). All tumours arose from the corpus, three were localised lower segment polyps, one a diffuse polypoid involvement of the endometrium. Histologically all of the tumours showed very similar appearances with closely packed, regular, tubular glands lined by low columnar epithelium, resembling most closely basal endometrial glands and surrounded by benign connective tissue which by simple tinctorial methods appeared to be largely smooth muscle. No heterologous components were seen. In two cases squamous metaplasia was extensive, in one microcalcification was present. The histological appearances favour a type of benign mixed Mullerian tumour but the appearances are not typical of Mullerian adenofibroma. Immunocytochemistry performed on 3 cases confirmed that the stroma was in large part smooth muscle, though much of the stroma stained only weakly with monoclonal antidesmin antibody.
Atypical polypoid adenomyofibromas (atypical polypoid adenomyomas) of the uterus. A clinicopathologic study of 55 cases. Longacre TA, Chung MH, Rouse RV, Hendrickson MR. Division of Surgical Pathology, Stanford University Medical Center, CA 94305, USA.	Am J Surg Pathol 1996 Jan;20(1):1-20 Abstract quote We present the clinicopathological and immunohistochemical features of 55 atypical polypoid adenomyofibromas, a definitional expansion of an entity previously reported as "atypical polypoid adenomyoma" (APA) of the uterus. Patients ranged in age from 25 to 73 (mean, 39.9) years. All but two of the patients were premenopausal, and 14 were undergoing evaluation for infertility. Histologically, the lesions featured a biphasic proliferation of architecturally complex and cytologically atypical endometrial glands within a myofibromatous stroma. The histologic pattern ranged from widely separated and loosely clustered irregular but branched glands embedded in broad zones of cellular myofibromatous stroma to those possessing crowded, markedly complex, branching glands separated by sparse intersecting fascicles of fibromuscular tissue. The stroma in all cases was actin or desmin positive or both. Morular/squamous metaplasia was present in all but two cases and florid in most. All cases exhibited architecturally complex glands, and in 25 cases the architectural complexity was indistinguishable from that of well-differentiated endometrial adenocarcinoma, as we have defined it; that is, they had a high architectural index. Twenty-nine patients were initially treated with polypectomy or curettage followed by hormonal therapy; persistent or recurrent APA developed in 45% of the patients in this group (33% with low architectural index vs. 60% with high architectural index). Five patients had successful pregnancies despite persistent disease. Superficial myoinvasion was identified in the hysterectomy specimen in two of 12 APAs with a high architectural index but not in 21 APAs with a low architectural index. All patients are alive and well 1 to 112 months after diagnosis (mean, 25.2 months). On the basis of this study, we propose that APAs with markedly complex glands (high architectural index) be designated "atypical polypoid adenomyofibromas of low malignant potential" (APA-LMP) to emphasize the potential risk for myometrial invasion. A treatment program featuring local excision accompanied by close follow-up is warranted for APA despite the presence of recurrent or persistent disease. Patients with APA-LMP may also, in selected cases, be managed with less than hysterectomy, although (as with the usual well-differentiated carcinoma) there is a small but definite risk associated with this approach.
VARIANTS

SPECIAL STAINS/IMMUNOPEROXIDASE/ OTHER	CHARACTERIZATION
IMMUNOPEROXIDASE
Atypical polypoid adenomyoma of the uterus. An immunohistochemical study of a case. Di Palma S, Santini D, Martinelli G. Divisione di Anatomia Patologica e Citologia, Istituto Nazionale Tumori, Milano, Italy.	Tumori 1989 Jun 30;75(3):292-5 Abstract quote We studied one case of atypical polypoid adenomyoma of the uerus immunohistochemically using antisera against keratins, vinentin, S-100 protein, desmin and actin. The stromal cells were reactive with anti-actin and antidesmin antibodies suggesting a muscular phenotype and confirming previous ultrastructural data. Immunohistochemical investigations have proved to be useful in differential diagnosis of APA with invasive adenocarcinoma, adenosarcoma and adenofibroma of the endometrium.
Atypical polypoid adenomyofibroma (APA) versus well-differentiated endometrial carcinoma with prominent stromal matrix: an immunohistochemical study. Soslow RA, Chung MH, Rouse RV, Hendrickson MR, Longacre TA. Division of Surgical Pathology, Stanford University Medical Center, California 94305, USA.	Int J Gynecol Pathol 1996 Jul;15(3):209-16 Abstract quote It can be extremely difficult in some cases to distinguish atypical polypoid adenomyomas (APAs) from invasive adenocarcinoma in an endometrial curettage or biopsy specimen. In order to determine if immunophenotypic features can be exploited to differentiate between these two entities in problematic cases, a series of APAs and myoinvasive well-differentiated endometrial carcinomas (WDCAs) were studied with a panel of standard immunohistochemical markers. All 23 APAs had stromal smooth muscle actin (SMA) reactivity, 12 of 23 had variable degrees of stromal desmin reactivity, and nine of 22 had CD34-positive stromal cells. All epithelial components of the APAs were cytokeratin (AE1 and CAM5.2) positive, whereas 22 of 23 were positive for estrogen receptor (ER) and progesterone receptor (PR). Among the 10 myoinvasive WDCAs, all contained at least some SMA-positive stromal cells, seven of 10 desmin-positive stromal cells, and four of eight CD34-positive stromal cells. All carcinomas studied demonstrated CAM5.2 and PR-positive epithelia; nine of 10 were ER positive. We conclude that the immunophenotype of APAs does not differ significantly from well-differentiated endometrial adenocarcinoma and that immunophenotyping is of little value in distinguishing APA from carcinoma. Because the stroma in APAs histologically and immunophenotypically more closely resembles a hybrid myofibromatous stroma, we prefer to refer to these lesions with the modified designation "atypical polypoid adenomyofibroma," although "APA" may be retained for clinical use.
ELECTRON MICROSCOPY
Atypical polypoid adenomyoma: a case report with ultrastructural examination. Delprado WJ, Stevens SM, Baird PJ.	Pathology 1985 Jul;17(3):522-5 Abstract quote A case of atypical polypoid adenomyoma occurring in a 40 yr-old female is reported. The lesion was composed of irregular glands lined by atypical epithelium lying in a spindle cell stroma containing smooth muscle cells. The mitotic count of the stroma was less than 1 per 10 high power fields. Squamous metaplasia was present in the glandular elements. Ultrastructural examination of the stroma confirmed the presence of smooth muscle cells. The lesion is compared with similar cases previously reported. The differential diagnosis is considered, including endometrial adenocarcinoma, adenomyosis, endometrial polyps and mixed Mullerian tumours. Atypical polypoid adenomyoma is a benign lesion, and conservative management is recommended.

GROSS APPEARANCE/ CLINICAL VARIANTS	CHARACTERIZATION
GENERAL
VARIANTS
Atypical polypoid adenomyoma of the uterus in a very old woman. Report of a case with immunohistochemical characterization of its stromal components and proliferative status. Kuwashima Y, Uehara T, Kurosumi M, Kishi K, Ohno H, Maruyama M, Takayama S. Department of Pathology, Saitama Cancer Center, Japan.	Eur J Gynaecol Oncol 1995;16(2):115-9 Abstract quote A case of atypical polypoid adenomyoma (APA) of the uterus in an 81-year-old patient is reported. The tumor arose in the uterine fundus as a polypoid mass and measured 9 cm in its longest diameter. Its histological appearance was similar to that of the reported cases, i.e. presence of atypical endometrial glands and a cellular smooth muscle stroma. However, the patient's age was extremely advanced, since APA has predominantly been reported to arise in premenopausal women. APA has been suggested as being related to prolonged estrogenic stimulation. But the fact that in this case the uninvolved endometrium was absolutely atrophic, negated this possibility. Immunohistochemistry for alpha smooth muscle actin was positive diffusely in the stroma. The proliferative status of the neoplastic glands was assessed by immunostaining for Ki-67 antigen. About 30% of the glands contained Ki-67 positive nuclei, and about 3% of the nuclei were positive in the glands. These figures are far below those of the usual endometrial adenocarcinoma, strongly suggesting that the APA was benign in nature.

PROGNOSIS AND TREATMENT	CHARACTERIZATION
PROGNOSTIC FACTORS
Coexistent atypical polypoid adenomyoma and endometrial adenocarcinoma. Mittal KR, Peng XC, Wallach RC, Demopoulos RI. Department of Pathology, New York University Medical Center, NY, USA.	Hum Pathol 1995 May;26(5):574-6 Abstract quote Atypical polypoid adenomyoma (APA) is a rare entity that is believed to follow a benign course. We report a case of APA with coexistent endometrial adenocarcinoma. The example raises the possibility that APA may progress to endometrial adenocarcinoma in some cases.
Two cases of endometrial adenocarcinoma arising from atypical polypoid adenomyoma. Sugiyama T, Ohta S, Nishida T, Okura N, Tanabe K, Yakushiji M. Department of Obstetrics and Gynecology, Kurume University School of Medicine, 67 Asahi-machi, Kurume City, 830-0011, Japan.	Gynecol Oncol 1998 Oct;71(1):141-4 Abstract quote Atypical polypoid adenomyoma (APA) most frequently presents as an endometrial polyp in premenopausal women and is believed to follow a benign course. In hysterectomy specimens from postmenopausal Japanease women, the endometrium contained an APA with an area of endometrial adenocarcinoma. A convincing transition zone between the APA and the adenocarcinoma was seen in our cases, suggesting that APA may develop into endometrial adenocarcinoma in postmenopausal women.
TREATMENT	Simple excision or removal