Purpose:To analyze immunohistochemically morules in endometrioid lesions to show that CD10 is a sensitive marker for morular metaplasia. Experimental Design: Immunohistochemical analysis of 53 instances of morular metaplasia comprising 1 cyclic endometrium and 52 endometrioid lesions associated with focal glandular complexity corresponding to 9 polyps, 4 atypical polypoid adenomyomas, 24 complex endometrial hyperplasias (18 with and 6 without atypia), 12 grade 1 endometrioid adenocarcinomas in early clinical stages of both uterus and ovary, and three ovarian adenofibromas. Immunohistochemistry in paraffin sections was done for CD10, h-catenin, estrogen and progesterone receptors, and cytokeratins 5-6, 7, 8, 13, 18, 19, 20, and 34h-E12. Results: Morules were negative for estrogen and progesterone receptors and had h-cateninp ositive nuclei. Cytokeratins 8, 18, 19 were positive; cytokeratins 7 and 20 were negative; and cytokeratins 5-6, 13, and 34h-E12 were weakly positive. All cases revealed strongly positive membranous CD10 staining in morules, which was absent in glands. CD10 positivity allowed easy identification of morules at low power in various types of surgical specimens and in curettings. CD10 also highlighted early morular metaplasia in glandular epithelium. In cases associated with squamous, keratinizing metaplasia, CD10 discriminated between both types of metaplasia. Conclusions: CD10 staining represents a useful marker of morules in endometrioid neoplasms of the female genital tract, permitting identification of lesions usually associated with an attenuated malignancy. Considering the immunohistochemical and genetic similarities of morules in tumors of different organs, it is likely that this marker may be also useful to diagnose morular metaplasia in similar neoplasms of extragenital locations.Morules (1) are nodular structures found in endometrial-type glands formed by a peculiar metaplastic non-keratinizing squamoid epithelium (2). Morphologically similar structures have also been described in neoplastic lesions in other anatomic sites, such as thyroid (3), lung (4, 5), stomach (6), pancreas (7), and colon (8).In both eutopic and ectopic endometrioid tissues, morules are almost invariably associated with the glandular architectural complexity of premalignant and low-grade glandular malignant lesions but are absent in high-grade ones. Thus, it can be said that the presence of morules in the endometrium relates well with an attenuated malignancy.This study deals with the immunohistochemical findings in a series of 53 cases of morular metaplasia from both uterus and ovary, showing for the first time that CD10 staining is a marker of morules, allowing its easy identification in various endometrioid lesions. Materials and MethodsA total of 53 cases of endometrioid morular metaplasia were collected from the files of the

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We report a case of a 9-cm mixed epithelial and stromal tumour of the kidney in an obese 70-year-old woman with diabetes. The ovarian-type stroma had a spindle cell component that was positive for progesterone receptors and had the hitherto unreported presence of abundant foci of luteinised stromal cells with characteristic immunohistochemical positivity to a-inhibin, calretinin, aromatase and gonadotropin-releasing hormone (GnRH) receptors. We conclude that the stromal component is identical to ovarian cortical stroma. We believe that ovarian-type stroma occurs in extragenital tumours as a result of an epithelial-stromal interaction in an environment of hormonal hyperstimulation.

We present, for the first time, two yolk sac tumors (YST) in women 37 and 18 years of age, one with a typical parietovisceral pattern and the other with a glandular pattern, which were associated with extensive areas of mucinous carcinoid (MC). The tumor in the first case had numerous nodules of tubulopapillary YST that merged with well-differentiated MC. This patient responded well to chemotherapy. The tumor in the second case consisted of an AFP-positive glandular YST, with a glandulopapillary pattern closely resembling fetal lung type adenocarcinoma, coexisting with an AFP-negative, cytokeratin 20-positive, atypical MC; transitional areas between the two components were also seen. In the material from the recurrences and metastases; however, no YST was present, the atypical MC having become the predominant component including areas that had become carcinomatous. There was a poor response to various chemotherapeutic regimens. AFP levels became negative during the course of disease paralleling the disappearance of the YST component and the overgrowth of an increasingly anaplastic MC. The patient died 1 year after diagnosis. We think that, in these cases, MC represented an unusual form of endodermal differentiation of the YST. It is important to differentiate the yolk sac and carcinoid components due to their different responses to chemotherapy and to evaluate the possibility of mucinous carcinoid developing into a highly aggressive carcinoma.

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