Kamaljeet Singh

Identifying mesonephric‐like adenocarcinoma of the endometrium by combining SOX17 and PAX8 immunohistochemistry

AimsMesonephric‐like adenocarcinoma (MLA) of the endometrium or ovary is a rare but distinct endometrial carcinoma which has a combination of characteristic morphological, immunohistochemical (IHC) and molecular features. SOX17 has been recently identified as a highly sensitive and specific marker for endometrial and ovarian carcinomas. In this study, we aimed to investigate SOX17 expression in MLA together with other IHCs to differentiate MLAs from other endometrial carcinomas.MethodsSeventeen previously diagnosed endometrial/ovarian MLAs were collected, and multiple IHCs were performed. Additionally, we performed SOX17, PAX8 and ER on tissue microarrays (TMAs) composed of 652 endometrial carcinomas from 2012 to 2015 when MLA diagnostic criteria were not established.ResultsAll 17 MLAs showed diffuse strong positive PAX8, negative ER and variable TTF1/GATA3 staining. Notably, all MLAs showed negative (n = 10) or focal weak/moderate (n = 7) staining for SOX17, which is more diffuse and stronger than PAX8 in other endometrial carcinoma subtypes. This finding prompted us to screen TMAs with 652 endometrial carcinomas diagnosed before MLA by an approach of combined SOX17 and PAX8 IHCs, and 14 cases with positive PAX8 but negative/focal weak SOX17 were identified. We further studied the 14 cases by examining morphology and performing additional IHCs (TTF1, GATA3, ER and CD10) and would classify seven (50%) of them as MLAs based on morphological features and positive CD10, TTF1 and/or GATA3 staining.ConclusionOur results suggest that a combination of SOX17 and PAX8 IHCs would aid in diagnosing MLA if the results show strong positive PAX8, but negative SOX17.

Morphologic and immunohistochemical study of HPV-related cervical adenosquamous carcinoma: Reappraisal of a poorly defined entity

Current WHO criteria require distinct glandular and squamous differentiation for diagnosis of adenosquamous carcinoma (AdSq). However, a subset of poorly differentiated cervical carcinoma exhibits ambiguous morphology with diffuse growth pattern. The current study explores whether these tumors belong to the adenosquamous subtype. After IRB approval, we retrieved 41 AdSq cases diagnosed at our institution between 2007 and 2024. H&E slides were reviewed. Immunohistochemical staining for p16, p40, p63, BerEP4, and Claudin-4 was performed. IHC was scored. Statistical analysis was performed with Python packages. Based on morphology only, out of the 41 AdSq cases, 11 fulfilled the WHO proposed criteria for classic AdSq (cAdSq). Twenty cases were classified as non-classic AdSq (nAdSq). All the rest also exhibited a solid growth pattern, but were reclassified as endocervical (3), endometrioid (6), and squamous carcinoma (1). Histologically, nAdSq lacked distinct spatially separate components of squamous or glandular differentiation. Instead, tumor cells exhibited ambiguous morphology with diffuse growth or, less frequently, in nests, characteristic vacuolated/foamy cytoplasm, pleomorphic nuclei, and inflamed stroma. All nAdSq showed block positivity for p16 like cAdSq. Significant portion of AdSq cases expressed the squamous marker p40 (58 % in nAdSq vs. 50 % in cAdSq). In contrast to pure adenocarcinomas or squamous cell carcinomas, 47 % (7/15) of nAdSq cases expressed both squamous and adenocarcinoma markers (p40 and BerEP4), with 5 (33 %) cases showing positivity for all four markers. Similarly, two cAdSq cases (22 %) showed universal positivity for all four markers, though p40 positivity was more focal and weaker in other instances. Despite morphological differences, the overall survival outcomes between nAdSq and cAdSq was not significantly different (p = 0.49). Many cervical carcinomas with diffuse growth pattern are likely the non-classic AdSq that do not contain spatially separate squamous and glandular components. Immunostaining may help in identifying this "non-classic" subtype of AdSq.

Small cell neuroendocrine carcinoma of vagina: Report of a unique case with literature review

Small cell carcinoma (SCC) of vagina is extremely rare. The association between this tumor and high-risk HPV infection is unclear. To our knowledge, HPV status has been reported in only 3 previous cases of SCC of vagina. Herein, we present a unique case of vaginal small cell carcinoma with discordant HPV testing results between vaginal and cervical samples. We also review and discuss findings from previously reported cases of small cell carcinoma of vagina.

Recurrent Primary Paget Disease of Vulva with Paget-Like Epithelial Cells in Papillary Dermis: Displaced or Invasion?

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.