Low-grade, low-stage endometrioid endometrial adenocarcinoma: a clinicopathologic analysis of 324 cases focusing on frequency and pattern of myoinvasion.
Patients with low-stage, low-grade endometrial adenocarcinomas have a favorable prognosis; however, a subset has a risk of recurrence and death. We were interested in evaluating patterns of myometrial invasion and correlating them with clinical outcome to potentially identify patients at increased risk. A total of 324 cases of low-stage Grade 1 endometrial adenocarcinoma were reviewed to identify those with myoinvasion. The myoinvasive cases were classified on the basis of the pattern of invasion: infiltrating glands, microcystic elongated and fragmented (MELF; a distinctive histologic variant of the infiltrative gland pattern), broad front, adenomyosis like, and adenoma malignum. Depth of invasion and lymphovascular invasion were recorded, and a clinical follow-up of at least 2 y was obtained, as most recurrences occur in this time frame. Ninety-eight of 324 (30%) cases were invasive; 75 had >2 y of follow-up, with an average length of follow-up of >7 y (range, 24-154 mo; mean 87 mo). All patients had a hysterectomy and bilateral salpingo-oophorectomy; 39 (52%) also underwent a lymphadenectomy. Twenty-seven (36%) were superficially invasive (<10% myoinvasion), 42 (56%) invaded 10% to 49%, and 6 (8%) invaded >50%. Six (8%) cases exhibited cervical stromal invasion (Stage II); the rest were Stage I (65 IA, 4 IB). The invasive patterns consisted of infiltrative glands (48; 65%), a broad front (16; 21%), MELF (5; 7%), adenomyosis like (5; 7%), and adenoma malignum like (1, 1%). There were 65 Stage 1A cases and, of these, the myoinvasive pattern was as follows: 41 infiltrating glands, 15 broad front, 5 MELF, and 4 adenomyosis like. There were 4 Stage IB cases, of which 2 had infiltrating glands, 1 had adenoma malignum, and 1 displayed adenomyosis-like invasion. Six (8%) cases had cervical stromal invasion (Stage II), of which 5 had an infiltrative pattern of growth and 1 displayed a broad front. Lymphovascular invasion was noted in 6 cases (8%), all of which had infiltrative glands. The majority of Grade 1 endometrioid endometrial adenocarcinomas do not invade the myometrium. In cases with invasion, the infiltrative gland pattern was associated with higher stage, (3/4 Stage IB, 5/6 Stage II), lymphovascular invasion (4/6 cases), and recurrence (2/75 cases), suggesting that this growth pattern may be associated with tumors having other histologic features typically associated with more aggressive behavior.
Department of Pathology, Brigham and Women's Hospital, Boston, MA, USA.
Charles M
CM
Quick
Taymaa
T
May
Neil S
NS
Horowitz
Marisa R
MR
Nucci
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018269:Carcinoma, Endometrioid / Q000473:pathology* / Q000601:surgery; D016889:Endometrial Neoplasms / Q000473:pathology* / Q000601:surgery; D005260:Female; D006651:Histocytochemistry; D006801:Humans; D008875:Middle Aged; D009215:Myometrium / Q000473:pathology*; D009364:Neoplasm Recurrence, Local / Q000473:pathology; D011379:Prognosis; D012189:Retrospective Studies