Colorectal cancer is the third leading cause of cancer-related death, and its incidence is rising in the younger patient population. In the past decade, research has unveiled several processes (underlying tumorigenesis, many of which involve interactions between tumor cells and the surrounding tissue or tumor microenvironment (TME). Interactions between components of the TME are mediated at a sub-microscopic level. However, the endpoint of those interactions results in morphologic changes which can be readily assessed at microscopic examination of biopsy and resection specimens. Among these morphologic changes, alteration to the tumor stroma is a new, important determinant of colorectal cancer progression. Different methodologies to estimate the proportion of tumor stroma relative to tumor cells, or tumor stroma ratio (TSR), have been developed. Subsequent validation has supported the prognostic value, reproducibility and feasibility of TSR in various subgroups of colorectal cancer. In this manuscript, we review the literature surrounding TME in colorectal cancer, with a focus on tumor stroma ratio.

Purpose: To investigate the clinical features and outcomes for conjunctival melanoma based on patient age. Methods: A retrospective review of patients with conjunctival melanoma managed at a single tertiary referral center from April 18, 1974, to September 9, 2019. Clinical features and outcomes were compared by patient age category at presentation (young ≤45 years, middle-aged 46–69 years, and older ≥70 years), with Kaplan–Meier and Cox proportional hazard analysis [hazard ratio (95% confidence interval)]. Results: There were 629 patients categorized as young in 130 (21%), middle-aged in 278 (44%), and older in 221 (35%). A comparison by age category (young vs. middle-aged vs. older) revealed that older patients had melanoma with greater number of affected quadrants (1.7 vs. 1.8 vs. 2.0, P = 0.001) and clock hours (3.9 vs. 4.2 vs. 5.2, P = 0.001). All patients were treated with surgical excision, with no difference in requirement for additional medical or radiation therapy. By 10-year Kaplan–Meier outcomes, older patients had more frequent visual acuity loss ≥3 lines (11% vs. 28% vs. 64%, P < 0.001) and local tumor recurrence (38% vs. 46% vs. 70%, P < 0.001). Hazard ratio for the oldest age group (age ≥70) revealed a 7.76-fold (3.33–18.09) increased risk for visual acuity loss (P < 0.001), and a 2.08-fold (1.32–3.28) increased risk of local tumor recurrence (P = 0.002). There was no difference by age in risk for enucleation, exenteration, locoregional lymph node involvement, distant systemic metastasis, or death. Conclusions: Older patients with conjunctival melanoma present with more extensive disease and have increased risk for visual acuity loss and local tumor recurrence.

Multinucleated tumor cells (MTCs) in clear cell renal cell carcinoma (ccRCC) are not well understood. Our study included ccRCC cases in a single institution between 2010 and 2019. We classified MTC as MTC with degenerative atypia (MTCD), MTC with no anaplasia (MTCNA), and MTC with anaplasia (MTCA). Clinicopathologic characteristics and outcomes were compared between MTC groups. In all, 92 of 256 people (36%) with ccRCC had MTC. People with ccRCC with MTCD and those with ccRCC but no MTC had similar clinicopathologic characteristics and outcomes. Also, MTCNA and MTCA were associated with larger tumor size, advanced pathologic tumor stage, higher World Health Organization/International Society of Urologic Pathologists nuclear grade, and higher metastatic potential (P < .001 for each parameter). Overall, MTCA was associated with an increased rate of recurrence (P = .004), higher metastatic potential (P < .001), and shorter time to metastasis (P = .033), regardless of tumor stage. Univariate Cox regression revealed MTCNA as a significant predictor of metastasis at 5 years (hazard ratio [HR], 4.171; 95% CI, 1.934-8.998); moreover, MTCA was a significant predictor of recurrence (HR, 5.723; 95% CI, 2.495-13.124), metastasis (HR, 12.024; 5.966-24.232), and death (HR, 5.661; 95% CI, 2.688-11.924) at 5 years. Although MTCD may not be relevant in tumor grading, MTCNA and MTCA are associated with adverse outcomes.

Fumarate hydratase deficient renal cell carcinoma (FHRCC) can exhibit a heterogenous immunoprofile. In the present case, a solitary 10.5 cm mixed cystic and solid left kidney tumor showed various growth patterns, involving renal sinus adipose tissue and the renal pelvis. Tumor cells showed prominent nucleoli and perinucleolar halos. Aberrant diffuse (>90%), strong, and membranous carbonic anhydrase 9 and variable GATA3 expression were present. Diagnostic loss of fumarate hydratase expression and 2-succinyl cysteine overexpression (cytoplasmic and nuclear) were identified. Carbonic anhydrase 9 and GATA3 expression in FHRCC is rarely reported in the literature, and may cause misdiagnosis of clear cell RCC and/or urothelial carcinoma.

Objectives: The concept of rete hyperplasia with hyaline globules simulating testicular yolk sac tumor was first reported in a mostly retrospective review over 30 years ago. Nonetheless, we continue to encounter examples where this scenario resulted in misdiagnosis. Herein, we sought to investigate the incidence of rete hyperplasia/hyaline globules in germ cell tumors and their associated subtypes and hypothesize an etiology. Methods: A consecutive series of 348 germ cell tumor orchiectomies was evaluated for the presence of rete hyperplasia and hyaline globules, with clinicopathologic features recorded. Results: The incidence of rete hyperplasia and/or hyaline globules in our cohort was 30%, with 56% of specimens with rete hyperplasia containing concomitant hyaline globules. Hyaline globules were more often identified in specimens with nonfocal rete hyperplasia (78%) vs focal rete hyperplasia (22%). Absence of a yolk sac tumor component was seen in over half (61%) of orchiectomies with concurrent rete hyperplasia/hyaline globules (n = 105), inclusive of tumors with “pure” subtypes (ie, pure seminoma, pure teratoma, or pure embryonal carcinoma). Of these 105 specimens, rete invasion was seen in only 48%; notably, Paneth cell–like metaplasia was identified in efferent ductules/epididymis in 13%. Conclusions: Rete hyperplasia and hyaline globules are not uncommon findings in the setting of germ cell tumors (including occurrences in various pure/mixed germ cell tumors) and can show striking overlap with yolk sac tumor. We hypothesize that these histologic pitfalls evolve secondary to testicular obstruction by the tumor mass. Recognition of and distinguishing this morphologic mimicry is fundamental to guide appropriate clinical management.

Aims Interobserver variability in the assessment of gastric neoplasia biopsies between most Western and Eastern (predominantly represented by Japanese in the literature) pathologists has been documented. It is unknown if such variability exists between the US and Korean pathologists in the current era. Methods Ten gastrointestinal (GI) pathologists from the USA (n=5) and South Korea (n=5) evaluated 100 scanned images of gastric (n=50) and colorectal (n=50) neoplasia biopsies and answered multiple questionnaires. Consensus was defined as the answer chosen by the majority. Cohen’s (κc) and Fleiss’ kappa (κf) values were calculated between the consensus of the two groups and among the raters, respectively. Results Both groups reached a consensus in the majority of cases (74%–100%) with slight to perfect intergroup (κc=0.049–1.000) and no to substantial intragroup (κf=−0.083 to 0.660) agreements. For gastric neoplasia, Korean pathologists relied heavily on cytoarchitectural atypia, whereas the US pathologists focused on stromal invasion when diagnosing adenocarcinoma. For colorectal neoplasia, the Korean pathologists identified concurrent intramucosal carcinoma when diagnosing invasive adenocarcinoma, while the presence of desmoplasia was a prerequisite for the diagnosis of invasive adenocarcinoma for the US pathologists. Conclusions For GI neoplasia biopsy interpretation, the diagnostic approach of Korean pathologists is similar to that of Eastern/Japanese pathologists. Consensus outperformed kappa statistics in capturing the magnitude of inter-rater and intergroup reliability, highlighting the potential benefit of consensus meetings to decrease the gap between Western and Eastern diagnostic approaches.