Endometrial polyps can be difficult to diagnose, especially when they are encountered in specimens obtained by biopsy or curettage 2-5. The initial clue to the presence of a polyp is usually the admixture of fragments of a normal cyclical endometrium along with morphologically different fragments 2,3. Identification of tissue fragments containing irregular glands, dense or fibrous stroma or thick walled vessels whose appearances contrast with the surrounding endometrium suggests the presence of a polyp 1-3.
Recently, Kim et al described a histologic feature that could be useful in the diagnosis of endometrial polyps; the parallel arrangement of the long axes of endometrial glands to the surface epithelium (PGE) 2.
In this study, we examined PGE with various histologic features in grossly identifiable polyps from hysterectomy or polypectomy specimens and correlated the frequency of these features with variables such as menstrual state, histopathologic type, and shape of the polyps.
Hematoxylin and eosin-stained sections of polyps were re-evaluated according to the diagnostic features such as thick-walled blood vessels, densely fibrous/collagenous stroma, hypercellular stroma of endometrial type, glandular irregularity, and the presence of surface epithelium in 3 sides. We also noted the presence of PGE.
Polyps were classified as sessile or pedunculated by shape and hyperplastic, functional, fibrous or mixed by histology as Kim et al. Described in their study 2. Hyperplastic polyps contain actively proliferating, irregularly shaped glands in hypercellular endometrial-type stroma. A functional polyp refers to normal midsecretory phase glandular pattern or decidualized stroma of the late secretory phase. Fibrous polyps have a dense collagenous stroma with mostly cystically dilated glands. Mixed polyps showed combinations of the above.
Data were analyzed using the statistical software package SPSS 11.0 for Windows. Chisquare test or Fisher's exact test was used to evaluate the diagnostic significance of each histologic variable according to the menstrual state, histopathologic type, and shape of the polyps. Differences were considered to be significant at p<0,05.
The most frequent histologic findings observed in both premenopausal and postmenopausal women were the presence of thick walled vessels and irregularly shaped glands (91.5% and 97.2%, respectively). In addition, we observed another histologic feature,that is parallel arrangement of the long axes of endometrial glands to the surface epithelium in 33 of 71 (46.4%) endometrial polyps. PGE was more common in polyps excised from premenopausal (56.4%) than in postmenopausal women (34.3%). PGE was found in 7 of 8 (87.5%) functional polyps, while 40.6% of hyperplastic, 50% of fibrous, and 38.9% of mixed polyps showed this characteristic feature (Figure 1). The association of PGE with functional polyps was statistically significant (p<0.05). In addition, twentynine of 33 (87.9%) polyps showing PGE were pedunculated (Table 1). There was no significant difference between the shape of the polyps and PGE in premenopausal and postmenopausal patients (p>0.05) (Table 2).
Table 1: Diagnostic findings according to the menstrual state, shape and histologic types
Table 2: Incidence of PGE by menstrual state and polyps' morphology
Recently, Kim et al. described a new characteristic feature that might be useful in the diagnosis of polyps, namely, endometrial glands that grow parallel to each other with their long axes also paralleling to the elongate sides of a pedunculated polyp 2.
In our study, 33 of 71 (46.4%) cases showed this characteristic feature. PGE was more prominent in pedunculated or functional polyps in premenopausal women when compared with sessile or other types of polyps in postmenopausal women. Our findings are consistent with the results of Kim et al. 2. When we consider that endometrial glands normally grow with their long axes perpendicular to the mucosal lining of the endometrial cavity, identifying glands with axes parallelling to the mucosal surface might be very helpful for diagnosing polyps.
In conclusion, the presence of thick walled vessels is the most frequently identified and reliable histologic feature in endometrial polyps, PGE, when present, could be an additional clue in the diagnosis of endometrial polyp in routine curettage specimens.
Abbreviation
PGE: Parallel arrangement of the long axes of endometrial glands' to the surface epithelium.
1) Sherman ME, Mazur MT, Kurman RJ. Benign Diseases of the Endometrum. In Kurman RJ (ed). Blaustein\'s Pathology of the Female Genital Tract, 5th ed., Springer Verlag, New York, 2002. pp. 448-452.
2) Kim KR, Peng R, Ro, JY, Robboy SJ. A diagnostically useful histopathologic feature of endometrial polip. The long axes of endometrial glands arranged parallel to surface epithelium. Am J Surg Pathol 2004;28:1057- 1062.
3) McCluggage WG. My approach to the interpretation of endometrial biopsies and curettings. J Clin Pathol 2006;59:801-812.