Collins, Katrina

Enteroblastic, hepatoid, and clear cell carcinomas are rare subtypes of colorectal carcinoma (CRC) with histologic and immunohistochemical (IHC) overlap. We assessed 37 CRCs that possibly represent these subtypes. Provisional criteria for each subtype, along with case photomicrographs and IHC data, were circulated among the authors to provide diagnostic interpretations. Based on plurality consensus, the carcinomas were classified as enteroblastic (n=13), hepatoid (n=6), and clear cell (n=18). Unanimous agreement was reached in 18% (3 clear cell, 3 hepatoid). Interobserver analysis revealed a mean pairwise Cohen κ of 0.63 (range: 0.32 to 0.91), with the hepatoid subtype eliciting the greatest consensus. Clear cell areas were the most likely to intermix with areas of conventional CRC ( P <0.001). Seven patients (20%) had inflammatory bowel disease (mostly linked to enteroblastic CRC). Twenty-three of 34 patients (68%) had nodal metastasis, and 12 (32%) had distant metastasis (mostly to the liver) at presentation. Median recurrence-free survival was 17 months, with enteroblastic cases the most likely to recur (54%, P =0.015). Median follow-up length was 27 months, with 14 patients (40%) dying of disease (representing 7 enteroblastic, 4 hepatoid, and 3 clear cell CRC). Mutations were identified in TP53 (n=8) , APC (n=3) , FBXW7 (n=2), and KRAS (n=1). Inflammatory bowel disease significantly worsened recurrence-free survival on multivariate analysis, while distant metastasis significantly worsened both recurrence-free and overall survival on multivariate analysis. Enteroblastic, hepatoid, and clear cell CRC demonstrate morphologic and IHC overlap, leading to interobserver variability in diagnosis. Given potential differences in clinical correlations and outcomes, more refined criteria are likely necessary.

According to the current WHO classification, noninvasive germ cell neoplasia of the testis comprises germ cell neoplasia in situ (GCNIS), specific forms of intratubular germ cell neoplasia, and gonadoblastoma. Because type II germ cell tumors (GCT, type II) arise from GCNIS, accurate detection of precursor lesions is diagnostically important. In preparation for the 2024 International Society of Urological Pathology (ISUP) Consensus Conference on genitourinary precursor lesions, which took place in Florence, Italy, an anonymous survey was distributed to ISUP members to assess current diagnostic practices regarding testicular precursor lesions. The literature and current WHO classification affirm the significance of precursor lesions in testicular tumours. Working Group 4—Precursor Lesions of the Testis—focused on their practical application by individual pathologists rather than establishing consensus from scientific data. There is strong agreement that GCNIS is the preferred and appropriate term for GCT precursor lesions and that its presence should be reported in cases of invasive GCT. Respondents also agree that “seminoma with intratubular nonseminoma” is the appropriate terminology for seminoma with an associated noninvasive nonseminomatous (embryonal carcinoma, yolk sac tumor, trophoblasts, or teratoma) component. Most pathologists prefer to use OCT3/4 as the primary immunohistochemical marker, and a panel was generally not considered necessary. No consensus is reached regarding the requirement for immunohistochemistry to confirm GCT precursor lesions in the testis. Three questions remain open: the value of subtyping intratubular lesions, the immunohistochemical approach to gonadoblastoma, and the criteria distinguishing Sertoli cell nodules from Sertoli cell tumors.

Pelvicalyceal invasion (PCI) is a relatively novel pT3a staging parameter for renal cell carcinoma (RCC) nephrectomies. While interobserver reproducibility staging studies of sinus/vascular invasion in RCC exist, a similar evaluation for PCI has not been performed. Moreover, in our experience, there is also diagnostic variability in how pathologists interpret PCI. Herein, we explore interobserver reproducibility among genitourinary (GU) pathologists. Twenty hematoxylin and eosin-stained digitized slides from RCCs (all grossly approaching the renal pelvis) were distributed to 31 GU pathologists to classify each as PCI or not PCI based on their respective clinical practices; slides with concomitant sinus/fat/vascular invasion were excluded. Slides were then evaluated for the following 4 morphologic features: tumor abutting renal pelvis, tumor pushing/indenting into the renal pelvis, polypoid configuration of tumor into the renal pelvis, and tumor eroding through renal pelvic urothelium. Interobserver reproducibility was assessed, and the morphologic features were correlated with PCI. Relationships between pathologists’ interpretations, morphologic features, and PCI were evaluated using hierarchical clustering. Although the diagnosis of PCI was relatively uniform with a majority agreement (>67%) reached in 16/20 slides, overall interobserver reproducibility was only moderate (kappa=0.601). While all 4 morphologic features were sensitive for PCI, polypoid configuration of the tumor into the renal pelvis and the tumor eroding through the renal pelvic urothelium were most specific (90%, 100%, respectively). Although we show general consensus among genitourinary pathologists on PCI assessment, clarifying the diagnostic guidelines with specific criteria should be included in pathologic staging systems.

Context.— Distinguishing between renal oncocytic tumors, such as renal oncocytoma (RO), and a subset of tumors with overlapping characteristics, including the recently identified low-grade oncocytic tumor (LOT), can present a diagnostic challenge for pathologists owing to shared histopathologic features. Objective.— To develop an automatic computational classifier for stratifying whole slide images of biopsy and resection specimens into 2 distinct groups: RO and LOT. Design.— A total of 269 whole slide images from 125 cases across 6 institutions were collected. A weakly supervised attention-based multiple-instance–learning deep learning (DL) model was trained and initially evaluated through 5-fold cross validation with case-level stratification, followed by validation using an independent holdout data set. Quantitative performance evaluation was based on accuracy and the area under the receiver operating characteristic curve (AUC). Results.— The developed model data set yielded generalizable performance, with a 5-fold average testing accuracy of 84% (AUC = 0.78), and a closely aligning accuracy of 83% (AUC = 0.92) on the independent holdout data set. Conclusions.— The proposed artificial intelligence approach contributes toward a comprehensive solution for addressing commonly encountered renal oncocytic neoplasms, encompassing well-established entities like RO along with the challenging “gray zone” LOT, thereby proving applicable in clinical practice.

Context.— Gastrointestinal manifestations of Kaposi sarcoma are rare but may cause morbidity. Lower gastrointestinal involvement is particularly rare, and lesions may resemble conventional bowel polyps. Objective.— To study 15 patients who presented with lower gastrointestinal tract Kaposi sarcoma with polypoid architecture. Design.— The surgical pathology files of the departments of pathology at multiple institutions were searched for cases of Kaposi sarcoma forming polyps in the lower gastrointestinal tract (jejunum, colon, rectum); 15 cases with such features were identified. Clinicopathologic information was extracted from the medical record and documented by reviewing individual hematoxylin-eosin–stained slides. Results.— The patients were 13 men and 2 women aged 26–80 years (median = 44 years). Gastrointestinal tract involvement was multifocal in 11 cases and unifocal in 4. The tumors involved the rectum, rectosigmoid junction, cecum, ascending colon, transverse colon, and descending colon and presented as polypoid lesions measuring 0.2–2.1 cm. Six patients had upper gastrointestinal tract involvement in addition to lower gastrointestinal lesions. Histologically, the tumors were characterized in 6 cases by a dense spindle cell proliferation in the lamina propria; however, the remaining cases showed only a subtle fascicular spindle cell proliferation in the lamina propria that did not form an expansile mass. Conclusions.— Biopsies of gastrointestinal polyps showing absence of the common features of hyperplastic or adenomatous polyps, particularly in immunocompromised patients, should be carefully examined for the presence of a stromal spindle cell proliferation. Use of immunohistochemical stains, particularly human herpesvirus-8, can help in establishing the correct diagnosis.

Colorectal carcinoma with sarcomatoid components (which includes so-called carcinosarcomas and sarcomatoid carcinomas) is a rare subtype with 50 reported cases in the literature and overlapping criteria with undifferentiated carcinoma. We collected and described 15 cases from 10 men and 5 women, with a mean age of 66 years. Symptoms included abdominal pain and gastrointestinal bleeding. Most tumors presented in the rectosigmoid region, with a mean size of 8.2 cm. The sarcomatoid component, on average, represented 58% of the tumors and took many forms, including spindled (10 cases), anaplastic (9 cases), and rhabdoid (3 cases); one case showed osteoid matrix. Tumor budding was usually high, and tumor-infiltrating lymphocytes were usually low. The sarcomatoid component was keratin-positive in 10 cases. One case showed loss of mismatch repair protein expression, and 2 cases showed SMARCA4 loss (1 also with SMARCA2 loss). Molecular testing identified mutations in KRAS (n=1), NRAS (n=2), BRAF (n=2), APC (n=1), and TP53 (n=1) in a few cases. Tumors often presented at advanced stage, with 11 cases pT4, 9 cases with nodal metastases, and 7 cases with distant metastases. Follow-up was available for 10 cases (median: 2 months), with 2 alive without disease, 3 alive with disease, and 5 dead. Our findings roughly corresponded with those in previously reported cases. Colorectal carcinoma with sarcomatoid components is rare and aggressive, with a poor prognosis for many patients. We suggest that spindled cells, anaplasia, heterologous elements, and/or a component with definable sarcomatous lineage be used to distinguish colorectal carcinoma with sarcomatoid components from undifferentiated carcinoma.