Poorly Cohesive Carcinoma of the Nonampullary Small Intestine: A Distinct Histologic Subtype With Prognostic Significance

IDH1-mutated Crohn's disease-associated small bowel adenocarcinomas: Distinctive pathological features and association with MGMT methylation and serrated-type dysplasia

AIMS

Patients with Crohn's disease (CrD) have an elevated risk for the development of small bowel adenocarcinomas (SBAs). Actionable isocitrate dehydrogenase 1 (IDH1) mutations have been reported to be more frequent in CrD-SBAs than in sporadic SBAs. The present study aimed to investigate the clinicopathological and immunophenotypical features, as well as methylation profiles, of IDH1-mutated CrD-SBAs.

METHODS AND RESULTS

An international multicentre series of surgically resected CrD-SBAs was tested for IDH1 mutation. Clinicopathological features, immunophenotypical marker expression and O6-methylguanine-DNA methyltransferase (MGMT) and long interspersed nuclear element-1 (LINE-1) methylation were compared between IDH1-mutated and IDH1 wild-type CrD-SBAs. Ten (20%) of the 49 CrD-SBAs examined harboured an IDH1 mutation and all the mutated cancers harboured the R132C variant. Compared to IDH1 wild-type cases, IDH1-mutated CrD-SBAs showed significantly lower rates of cytokeratin 7 expression (P = 0.005) and higher rates of p53 overexpression (P = 0.012) and MGMT methylation (P = 0.012). All three dysplastic growths associated with IDH1-mutated SBAs harboured the same IDH1 variant (R132C) of the corresponding invasive cancer, and all were of non-conventional subtype (two serrated dysplastic lesions and one goblet cell-deficient dysplasia). In particular, non-conventional serrated dysplasia was significantly associated with IDH1-mutated CrD-SBAs (P = 0.029). No significant cancer-specific survival difference between IDH1-mutated CrD-SBA patients and IDH1 wild-type CrD-SBA patients was found (hazard ratio = 0.55, 95% confidence interval = 0.16-1.89; P = 0.313).

CONCLUSIONS

IDH1-mutated CrD-SBAs, which represent approximately one-fifth of total cases, are characterised by distinctive immunophenotypical features and methylation profiles, with potential therapeutic implications. Moreover, IDH1-mutated non-conventional, serrated dysplasia is likely to represent a precursor lesion to such CrD-SBAs.

A Clinicopathologic Comparison Between Early-Onset and Late-Onset Small Bowel Adenocarcinoma: A Multicenter International Study

INTRODUCTION

Early-onset small bowel adenocarcinoma (EO-SBA) is a rare and poorly characterized entity.

METHODS

This retrospective study conducted on an international multicenter cohort of 208 patients with SBA aimed at comparing clinicopathologic features of EO-SBA (age younger than 50 years at SBA diagnosis) and late-onset SBA (age 50 years or older at SBA diagnosis).

RESULTS

The presence of predisposing pathologic conditions was significantly more common in the EO-SBA group compared with that in the late-onset SBA group ( P = 0.003, Fisher exact test; relative risk: 1.50, 95% confidence interval: 1.20-1.86). This difference is mainly due to the significantly higher prevalence of celiac disease among patients with EO-SBA.

DISCUSSION

EO-SBA is strongly associated with predisposing conditions, particularly with celiac disease, highlighting the importance of routine screening for celiac disease in patients with EO-SBA.

Malignant Transformation of Long-Standing Ileal Crohn's Disease Likely Favors Signet Ring Cell Adenocarcinoma Histology

Signet ring cell adenocarcinomas (SRCCs) are a rare and aggressive histological subtype of adenocarcinomas typically with poor prognosis usually secondary to late stage at detection. In the small bowel, they constitute only 1% of all malignancies. In the last decade, there have been multiple case reports and small case series that have identified SRCCs, typically in the ileum, in patients with Crohn's disease. Crohn's disease is a transmural inflammatory condition that normally manifests in the distal ileum and colon, and is known to temporally increase the risk of malignancy. Given the profound rarity of SRCCs, establishing an association between Crohn's disease and SRCC is challenging. In this study, we performed a systematic review of case reports and small case series describing small bowel SRCCs in Crohn's disease patients. Most cases were found in the distal/terminal ileum, at a mean age of 59 years old. Virtually all tumors were locally advanced (pathological T stage 3 and 4), typically with at least N1 nodal disease. Two case studies (one is a case-control study and the other a cohort design) demonstrated that small bowel SRCC, as opposed to conventional adenocarcinoma, was significantly correlated to a history of Crohn's disease (35% vs. 0%, 73.5% vs. 28.5%), with a propensity to arise in the ileum (95% vs. 30%, 66.7% vs. 42.1%), and at earlier mean age (43 vs. 68 years, 53.7 vs. 61.7 years). We additionally used the Surveillance, Epidemiology, and End Results (SEER) database for insights into the clinicoepidemiological characteristics of ileum SRCCs. SRCCs composed 28.1% of all ileal SRCCs, compared to 11.0% for the adenocarcinomas, with a younger age at diagnosis (60.7 vs. 64.6 years), more distant disease at presentation (41.3% vs. 26.4%), and shorter overall median survival time (20 vs. 39 months). In summary, while there is limited direct evidence to support an association between small bowel SRCC and Crohn's disease, the phenomenon has been increasingly documented in the literature in the last decade. Clinicians treating Crohn's disease patients should consider this in their differential diagnosis, particularly when managing disease complications, as early detection and surgical intervention offer the best prognosis.

Mismatch repair deficiency as prognostic factor for stage III small bowel adenocarcinoma: A multicentric international study

BACKGROUND

Small bowel adenocarcinoma (SBA) is a rare cancer with an aggressive behavior. No study has specifically addressed the putative prognostic role of mismatch repair status in stage III SBAs.

AIMS

We aimed to investigate whether mismatch repair deficiency is associated with cancer-specific survival in a Western cohort of patients with stage III SBAs.

METHODS

In this retrospective multicentric international cohort study, we enrolled 70 patients who underwent surgically resection for stage III SBAs and we analyzed the frequency of mismatch repair deficiency, tested by immunohistochemistry for mismatch repair proteins and by polymerase chain reaction for microsatellite instability, and its association with cancer-specific survival and other clinic-pathologic factors.

RESULTS

We found sixteen (23%) patients with mismatch repair deficient adenocarcinoma, without discordance between immunohistochemical and polymerase chain reaction for microsatellite instability analyses. Mismatch repair deficiency proved to be associated with a better outcome both at univariable analysis (hazard ratio: 0.28, 95% confidence interval: 0.08-0.91, p: 0.035) and in bivariable models adjusted for patient age or gender, tumor site, pT4 stage, tumor budding, and perineural invasion.

CONCLUSION

This study highlights the importance of testing mismatch repair status to improve prognostic stratification in stage III SBAs.

Poorly cohesive duodenal carcinoma mixed with signet ring cell carcinoma with systemic metastasis: a case report and literature review

Poorly cohesive duodenal carcinoma mixed with signet ring cell carcinoma is very rare, and no cases have been reported. When distant metastasis occurs, it is very easy to be misdiagnosed. We report the first case of a 52-year-old man with poorly cohesive carcinoma of the duodenum mixed with signet ring cell carcinoma with systemic metastasis. The process of its diagnosis and differential diagnosis is highlighted.

Claudin-18 expression in small bowel adenocarcinoma: a clinico-pathologic study

Non-ampullary small bowel adenocarcinoma is a rare neoplasm with an ominous prognosis, whose incidence is higher in some chronic immuno-inflammatory conditions, such as coeliac and Crohn's disease. Recently, claudin 18.2, a transmembrane protein normally expressed in gastric mucosa, has been recognized as a novel pan-cancer therapeutic target, and several clinical trials with claudin-18-directed drugs have shown promising results on various gastrointestinal malignancies. This is the first study focusing on claudin-18 expression in small bowel adenocarcinomas. The immunohistochemical expression of claudin-18 (clone 43-14A) was assessed in 81 small bowel adenocarcinomas of diverse aetiologies and correlated with several clinico-pathologic features and patient survival. We found that 28% of adenocarcinomas were immunoreactive for claudin-18, with cutoff values of ≥1% at any intensity, while 6% of cancers showed immunoexpression of ≥75% with 2+/3+ score. Moreover, claudin-18 (≥1%) was positively associated with cytokeratin 7 (CK7) and MUC5AC expression, showing CK7+/MUC5AC+ carcinomas the highest rate of positive cases, whereas a negative correlation was found between claudin-18 and CDX2 expression. In addition, some cancer-adjacent dysplastic growths and foci of gastric-type metaplasia in Crohn's disease-associated cases showed claudin-18 immunoreactivity. Survival analysis showed a non-significant trend towards a worse cancer-specific survival for claudin-18-positive cases. A fraction of small bowel adenocarcinomas, mainly sporadic or Crohn's disease-associated, and often exhibiting a non-intestinal immunoprofile, expressed claudin-18, suggesting that claudin-18-directed targeted therapy is worth investigating in such cancers.