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While histological diagnosis of Paget disease of vulva is mostly straightforward, identifying and confirming invasion can be challenging. Often invasion is accompanied by epidermal hyperplasia, marked inflammatory response and desmoplastic reaction. Diagnosis of invasion in Paget disease portends a poor outcome. We report findings from a recurrent primary vulvar Paget disease where overall histomorphology of possible invasive disease is unusual and raises a possibility of displacement of Paget cells in the dermis. We compare histology of the index case with known invasive vulvar Paget disease cases retrieved from our pathology archives. Unique histomorphology in the index case suggests a possibility of previous excision related dermal displacement of Paget cells. [ABSTRACT FROM AUTHOR]

Low-grade serous carcinoma of the ovary is an uncommon lesion, composing approximately 3% of ovarian neoplasms. It typically arises in association with a serous borderline tumor and is most often at an advanced stage upon diagnosis. Gene mutations in BRAF and KRAS are characteristic. Various histologic architectural patterns are known, such as papillary, micropapillary, inverted micropapillary, glandular and nested. We report a case of low-grade serous carcinoma arising years after a serous borderline tumor and contralateral teratoma; the low-grade serous carcinoma showed two patterns: micropapillary growth and a previously unreported form of solid pattern manifesting as large tumor islands without slit-like spaces. This unusual solid morphology raises the differential diagnosis of high-grade serous carcinoma, which would result in different clinical management. The presence of areas with classic micropapillary architecture, in addition to the absence of high-grade cytonuclear atypia and marked pleomorphism, support the diagnosis of low-grade serous carcinoma. Immunohistochemical stains for p53 and p16 failed to show abnormal patterns characteristic of high-grade serous carcinoma. The patient declined chemotherapy and is on letrozole; she has had recurrent right pleural effusions over six months of follow-up after surgery. [ABSTRACT FROM AUTHOR]

Mesonephric-like adenocarcinoma (MLA) of the endometrium shows a variety of morphologic appearances, including small glands, tubules with eosinophilic materials in the lumen, prominent papillary patterns, spindled cells, solid formations, and corded and hyalinized patterns. Unique morphology, characteristic immunohistochemical staining patterns, molecular alterations, and awareness of the pathologists make it possible to identify this tumor accurately. This report of two additional morphologic patterns, intestinal goblet cells mimicking intestinal-type mucinous carcinoma and squamous differentiation with spindle and epithelioid cells mimicking carcinosarcoma of the endometrium will expand the literature on MLA. [ABSTRACT FROM AUTHOR]

To study the expression of HER2 in high-grade FIGO3 endometrial endometroid carcinoma (EEC) and to correlate our findings with the clinicopathologic characteristics of this tumor. HER2 expression by immunohistochemistry (IHC) was performed on 10% formalin-fixed paraffin embedded tissue on cases diagnosed as FIGO3 EEC. HER2 expression was interpreted as negative (0), low (1+ and 2+) or positive (3+) using similar criteria as in the breast. HER2 amplification by Fluorescence in situ hybridization (FISH) was performed on cases interpreted as 2+ and 3+ by IHC. One hundred and forty-three FIGO3 EEC were identified. Of these, 70 (49%) cases were HER2 negative (IHC 0), and 73 (51%) cases expressed/amplified HER2 by IHC and/or FISH. Of the 73 cases expressing or amplifying HER2, 59 cases were IHC 1+, 12 cases were IHC 2+, and 2 cases were IHC 3+. FISH testing was performed in 12 cases. Only one of the two HER2 IHC 3+ cases showed HER2 gene amplification by FISH and the other 11 cases were not amplified. The 5-year overall survival (OS) rate for HER2 IHC 1+ cases was 92.20% (95% CI: 83.97–100.00), and the 5-year OS rate for HER2 IHC 2+/3+ cases was 89.50% (95% CI: 56.41–100.00). Our findings indicate that about one half of FIGO3 EEC variably expresses HER2 and with the emerging concept of "HER2 low", anti-HER2 agents may be explored as potential therapeutic options in these patients, for possible survival benefits. [Display omitted] • About 50% of FIGO3 endometrial endometrioid carcinomas (EEC) express the HER2 protein with varying intensities. • Amplification or overexpression of HER2 in FIGO3 EEC is very low. • The therapeutic implication of low-level expression of HER2 in FIGO3 EEC is largely unknown. • Anti-HER2 therapy might be explored as a treatment option in low-level HER2 expression in FIGO3 EEC with potential benefits. [ABSTRACT FROM AUTHOR]

Context.--: Human papillomavirus (HPV) in the postmenopausal age group is complex, with infected patients in this age group at increased risk of progressing to invasive disease and showing decreased clearance of the virus. Additionally, atrophic changes of the cervix can make histologic distinction of high-grade squamous intraepithelial lesions (HSILs) difficult. Objective.--: To determine morphologic and ancillary testing characteristics of atrophy and HSIL in postmenopausal patients. Design.--: Files of patients at least 65 years of age were examined, with 81 patients (109 cases [53 benign, 56 HSIL]) included in the study. Results of morphology, immunostaining (p16 and Ki-67), and HPV RNA in situ hybridization (ISH) were noted on all cases with available material. Results.--: Atrophy was present in 96 of 109 cases (88%) overall. Coarse nuclear chromatin was noted in none of the benign cases, in 19 of 30 HSIL biopsies (63%), and in 24 of 26 HSIL excisions (92%). All benign cases were negative for p16 and ISH. In the HSIL cases, 45 of 53 (89%) were positive for p16, and of cases with sufficient tissue for ISH, 44 of 45 (98%) were positive. Of the ISH/p16 discordant cases (n = 7), most were p16 negative/ISH positive (6 of 7; 86%), whereas 1 of 7 (14%) was p16 positive and ISH negative. A majority of HSIL cases showed near-full-thickness elevation of Ki-67 (45 of 54; 83%), whereas mitotic figures were less elevated. Conclusions.--: In postmenopausal patients with HSIL, mitotic activity is not reliably elevated, but Ki-67 is consistently high. ISH is a more direct method of HPV detection and should be considered in cases where morphology and immunolabeling show discordance. [ABSTRACT FROM AUTHOR]

(A) Alternating mucinous and ciliated epithelia, mucinous epithelia with cilia, acidic, blue mucin, and neutral mucin (hematoxylin and eosin [H&E] 40×); (B) Predominantly low columnar mucinous epithelia (H&E 40×); (C) Exceedingly tall columnar mucinous epithelia (H&E 40×); (D) Bird's eye view of the seromucinous cystadenoma (H&E 4×). Microscopic examination revealed a cystadenoma lined by 2 types of epithelia: tubal-type ciliated epithelium alternating with endocervical-type mucinous epithelium. Seromucinous tumors, introduced in the 2014 World Health Organization classification as one of the categories of ovarian epithelial tumors, are defined as neoplasms with 2 or more Müllerian epithelial cell types.[1] Benign tumors of this category are rare and may represent fewer than 1% of benign epithelial neoplasms of the ovary.[1],[2] We report a case of a 55-year-old female who presented with back pain and was found to have a complex cystic lesion of the left adnexa by computed tomography examination. [Extracted from the article]