Updates in Appendix Pathology: The Precarious Cutting Edge

Mucinous neoplasms associated with mature cystic teratomas: A clinicopathologic study of 50 cases: Are we ready for nomenclature change?

Mucinous neoplasms associated with ovarian teratomas (MOvNTs) are uncommon with only a few large series published thus far. Their clinicopathologic features are evaluated in this multi-institutional study. Fifty MOvNTs were retrieved from the files of four institutions over 16-years (yr). Patient age, CEA and CA-125 levels, laterality, tumor size, type of mucinous tumor (according to gynecologic pathology criteria and proposed appendiceal nomenclature when applicable), immunohistochemistry (IHC), FIGO stage, presence of pseudomyxoma ovarii and peritonei, treatment, follow-up in months (mos), and outcome were recorded. Patients ranged in age from 17 years to 74 years (mean 43, median, 42). Increased CA-125 levels correlated with mucinous carcinoma and mucinous borderline tumor (p=0.0270), and CEA correlated with mucinous carcinoma (p=0.0256). Mucinous neoplasms were either cystadenomas (16), borderline tumors (20) or carcinomas (14). Forty-one were Mullerian/surface epithelial type and 9 were appendiceal-like. Using appendiceal nomenclature: Seven were low grade mucinous appendiceal neoplasms and 2 high grade appendiceal neoplasms. IHC: 39 % were CK20/CDX2/SATB2 positive and 61 % were CK7 > CK20 (+), and SATB2-. Almost all patients presented with FIGO stage I disease; except one each with FIGO II and IIIC disease. All patients had surgical resection, and 10 patients had adjuvant therapy. Recurrences occurred in 4 patients (range: 10-84 mos). At last follow-up (median 60 mos): 33 patients had no evidence of disease, 3 died of disease, 1 was alive with disease, 2 died of other causes, and 11 were lost to follow-up. MOvNTs are usually Mullerian/surface epithelial type and FIGO stage I. As the only patients with adverse outcome were those who had a diagnosis of mucinous carcinoma or microinvasive carcinoma, whether of appendiceal-like or Mullerian/surface epithelial type, using established gynecologic, rather than GI criteria for classifying all types of MOvNTs is recommended.

Occult appendix pathology in patients undergoing colorectal cancer resection and prophylactic appendectomy

BACKGROUND

The risk-benefit balance of prophylactic appendectomy in patients undergoing left colorectal cancer resection is unclear. The aim of this report is to assess the proportion of histologically abnormal appendices in patients undergoing colorectal cancer resection in a unit where standard of care is appendectomy, with consent, when left-sided resection is performed.

METHODS

A retrospective study on a prospectively collected database was conducted in a single tertiary-care center. Overall, 717 consecutive patients undergoing colorectal cancer resection between January 2015 and June 2021 were analyzed. The primary outcome was the proportion of histologically abnormal appendix specimens at prophylactic appendectomy. The secondary outcome was complications from prophylactic appendectomy.

RESULTS

Overall, 576/717 (80%) patients had appendectomy at colorectal cancer surgery. In total, 234/576 (41%) had a right-/extended-right hemicolectomy or subtotal colectomy which incorporates appendectomy, and 342/576 (59%) had left-sided resection (left-hemicolectomy, anterior resection or abdominoperineal excision) with prophylactic appendectomy. At definitive histology, 534/576 (92.7%) had a normal appendix. The remaining 42/576 (7.3%) showed abnormal findings, including: 14/576 (2.4%) inflammatory appendix pathology, 2/576 (0.3%) endometriosis, 8/576 (1.4%) hyperplastic polyp, and 18/576 (3.1%) appendix tumors, which encompassed six low-grade appendiceal mucinous neoplasms (LAMNs), three carcinoids, and nine serrated polyps. In the 342 patients who had prophylactic appendectomy, 10 (2.9%) had a neoplasm (two LAMN, three carcinoids, and five serrated polyps). There were no complications attributable to appendectomy.

CONCLUSION

Occult appendix pathology in patients undergoing colorectal cancer resection is uncommon when prophylactic appendectomy was performed. However, approximately 3% of patients had a synchronous appendix neoplasm.

Cancer-specific survival in non-mucinous appendiceal adenocarcinomas after local resection versus right hemicolectomy: A Surveillance, Epidemiology, and End Results database study

BACKGROUND

Adenocarcinomas of the appendix are rare cancers for which no National Comprehensive Cancer Network guidelines exist, and for patients who undergo resection with curative intent, there is a paucity of data on prognostic factors affecting long-term cancer-specific survival. We aimed to compare the cancer-specific survival outcomes in adult patients with appendiceal non-mucinous adenocarcinoma undergoing either local resection versus right hemicolectomy.

METHODS

This was a retrospective study from the National Cancer Institute Surveillance, Epidemiology, and End Results of patients who underwent curative resection over a 15-year period (2004-2019) for primary appendiceal adenocarcinoma. Out of 16,699 patients, 14,945 were excluded (exclusion criteria were non-adenocarcinoma histological types and patients with regional or distant metastasis as per National Cancer Institute Surveillance, Epidemiology, and End Results stage). Effects of factors (age, race, tumor biology [mucinous versus non-mucinous tumors], the extent of resection of the primary lesion, and lymph nodes) on cancer-specific long-term survival were studied. Survival analysis was performed using the Kaplan-Meier method. Survival outcomes were reported as mean survival (months).

RESULTS

Of 1,754 patients, 827 (47.1%) were women, and 927 (52.1%) were men. The mean age in years (± standard deviation) was 62.43 ± 14.3. The racial distribution was as follows: Black 237 (13.5%), White 1,398 (79.7%), and Other 119 (6.8%). A total of 771 (44.6%) underwent local resection (appendectomy or segmental resection of colon without lymph node resection), and 983 (55.4%) underwent hemicolectomy with lymph node resection. Favorable survival prognosticators were age <50 years, White race, and well-differentiated histology. Patients with mucinous tumors experienced better survival. Patients who underwent right hemicolectomy with lymph node resection experienced better survival compared with those who had an appendectomy or segmental colonic resection for non-mucinous tumors rather than mucinous tumors.

CONCLUSION

We report novel demographic, tumor-related, and operative prognostic factors impacting long-term cancer-specific survival in patients who undergo resection for appendiceal adenocarcinoma. The extent of resection of the primary lesion with draining lymph nodes determines long-term cancer-specific survival in non-mucinous appendiceal adenocarcinomas.

Correlation between PSOGI pathological classification and survival outcomes of patients with pseudomyxoma peritonei treated using cytoreductive surgery and HIPEC: national referral centre experience and literature review

Objectives

The Peritoneal Surface Oncology Group International (PSOGI) consensus subdivided pseudomyxoma peritonei (PMP) into four groups according to histopathological features. The aim of this paper is to report survival outcomes after cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) from a national referral centre and to correlate the PSOGI classification with survival.

Methods

A retrospective study of a prospectively maintained database was performed. Consecutive patients treated with CRS + HIPEC for PMP of appendiceal origin were included (September-2013 to December-2021). Pathological features of the peritoneal disease were used to classify patients into the four groups proposed by PSOGI. Survival analysis was performed to evaluate the correlation of pathology on overall survival (OS) and disease-free survival (DFS).

Results

Overall, 104 patients were identified; 29.6 % were reclassified as acellular mucin (AM), 43.9 % as low-grade mucinous carcinoma peritonei (LGMCP), 22.4 % as high-grade MCP (HGMCP) and 4.1 % as HGMCP with signet ring cells (HGMCP-SRC). Median PCI and rate of optimal cytoreduction were 19 and 82.7 %, respectively. Median OS and DFS were not reached, 5-year OS and DFS were 88.6(SD 0.04) % and 61.6(SD 0.06) %, respectively. Log-Rank test revealed significant differences in terms of OS and DFS across the different histological subgroups (p<0.001 in both cases). However, histology did not retain its significance in the multivariate analysis for OS or DFS (p=0.932 and p=0.872, respectively).

Conclusions

Survival outcomes after CRS + HIPEC for PMP are excellent. The PSOGI pathological classification correlates with OS and DFS, but differences were not significant at multivariate analysis when adjusted for other prognostic factors.

Analysis of appendiceal neoplasms in 1,423 appendectomy specimens: a 10-year retrospective cohort study from a single institution

OBJECTIVE

This study aimed to reveal the incidence, clinicopathological, and oncological outcomes of appendiceal neoplasms.

METHODS

This is a retrospective cohort study from a single institution. Patients with a pathological diagnosis of malignancy who underwent appendectomy between January 2011 and 2021 were included in the study, and groups were formed according to pathological type. Clinical, pathological, and oncological results were compared in these groups.

RESULTS

The incidence of neoplasia was 2.38% (n=34) in a cohort of 1,423 appendectomy cases. Of the cases, 56% (n=19) were female. The median age in the entire cohort was 55.5 (range: 13-106) years. In the cohort, the rate of neuroendocrine tumor mucinous cystadenoma adenocarcinoma, and low-grade appendiceal mucinous neoplasm, according to the American Joint Committee on Cancer classification of appendiceal neoplasms, was 32.3% (n=11), 26.4% (n=9), 26.4% (n=9), and 14.7% (n=5), respectively. Neuroendocrine tumor patients (median age: 35 years) were younger than the other groups (p=0.021). Secondary complementary surgery was performed in 66.7% (n=6) of adenocarcinoma patients and 27.3% (n=3) of neuroendocrine tumor patients. Right hemicolectomy was performed in all neuroendocrine tumor patients requiring secondary surgery, while right hemicolectomy was performed in three adenocarcinoma patients and cytoreductive surgery and hyperthermic intraperitoneal chemotherapy in three adenocarcinoma patients. After a median follow-up of 44.4 months (95% confidence interval: 18.6-70.1), the mean survival rate was 55% in appendiceal adenocarcinoma patients compared to 100% in neuroendocrine tumor patients.

CONCLUSION

Appendiceal neoplasms are rare but remain an important cause of mortality. Appendiceal adenocarcinomas are associated with poorer oncological outcomes compared to other neoplasms.

Which classification system defines best prognosis of mucinous neoplasms of the appendix with peritoneal dissemination: TNM vs PSOGI?

AIMS

Several classification systems are used for pseudomyxoma peritonei. The four-tiered classification system proposed by Peritoneal Surface Oncology Group International (PSOGI) and the two-tiered proposed by the eighth edition of the American Joint Committee on Cancer (AJCC) result from evolution in terminology and pathological insight. The aim is to evaluate the impact of PSOGI and eighth edition of the AJCC classifications on survival.

METHODS

Pathological slides were reviewed from a prospectively maintained database including patients treated with cytoreductive surgery and hyperthermic intraperitoneal chemotherapy for an appendiceal mucinous neoplasm with peritoneal dissemination between January 2009 and December 2019. Patients were reclassified according to PSOGI and AJCC eighth edition criteria. Survival analysis evaluated the impact of each classification system on overall survival (OS) and disease-free survival (DFS) while the concordance-index evaluated their predictive power.

RESULTS

95 patients were identified; 21.1% were reclassified as acellular mucin, 55.8% as low-grade mucinous carcinoma peritonei, 8.4% as high-grade MCP (HGMCP) and 14 as HGMCP with signet ring cells. Median OS was not reached, 5-year OS and DFS were 86.1% and 51.5%, respectively. Multivariate analysis revealed significant associations with OS (PSOGI: HR 10.2, p=0.039; AJCC: HR 7.7, p=0.002) and DFS (PSOGI: HR 12.7, p=0.001; AJCC: HR 3.7, p<0.001). The predictive capacity of both classification systems was unacceptable for OS and DFS (concordance-index values <0.7).

CONCLUSIONS

Both classification systems behaved similarly when stratifying our series into prognostic groups. The PSOGI classification provides better histopathological description, but histology alone is insufficient for adequate patient prognostication.

Goblet cell adenocarcinoma of the appendix: an update and practical approach to diagnosis and grading

Goblet cell adenocarcinoma is a rare appendiceal tumour with amphicrine differentiation that has distinct morphologic and clinical features compared to carcinomas seen elsewhere in the gastrointestinal tract. These tumors have engendered considerable confusion in the literature regarding their classification, and they have been described under several different names including goblet cell carcinoid, adenocarcinoid, and adenocarcinoma, among others. In the recent fifth edition of the World Health Organization Classification of Digestive System Tumors, goblet cell adenocarcinoma is the preferred diagnosis because of the increasing recognition of a frequent co-existing high-grade adenocarcinoma component. This review will present the clinicopathologic, molecular, and immunohistochemical features of goblet cell adenocarcinoma and discuss the current challenges in diagnosis, grading, and clinical management.

Accessory spleen presenting with an episode of acute appendicitis; a case report of a very rare case

Introduction

The accessory spleen (AS) is a condition that results from improper placement of spleen cells. About 95 % of ASs are located in the splenic hilum proximal to the tail of the pancreas. Here we present a 23-year-old male diagnosed with AS in the appendix, following an episode of acute appendicitis.

Case presentation

A 23-year-old male patient who presented with typical symptoms of appendicitis and the examination and paraclinical findings were in favor of appendicitis. Intraoperative findings showed an inflamed appendix and a 2 cm solid mass in the mesoappendix. The pathology report showed acute appendicitis and normal spleen tissue.

Conclusion

The current study indicated an abnormal location of AS placed in the mesoappendix, which was presented with an episode of acute appendicitis.

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The accessory spleen (AS) is a condition that results from improper placement of spleen cells.

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About 95% of ASs are located in the splenic hilum proximal to the tail of the pancreas.

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The remaining 5% are formed in the gastrosplenic ligament, wall of the stomach, wall of the intestine, and the mesentery or pelvic cavity

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The current study indicated an abnormal location of AS placed in the mesoappendix, which was presented with an episode of acute appendicitis

Trends of colorectal cancer incidence according to age, anatomic site, and histological subgroup in Bavaria: A registry-based study

Background

Recent studies reported an increase in colorectal cancer incidence for adults below 50 years. There is a lack of studies distinguishing between histological subgroups, especially from Europe.

Methods

Using data from the Bavarian Cancer Registry, we analyzed incidence trends in colorectal cancer by age (20–29, 30–39, 40–49, and 50 years and above), anatomic site (colon without appendix, appendix, and rectum), and histological subgroup (adenocarcinoma and neuroendocrine neoplasm) from 2005 to 2019. We calculated 3-year average annual age-standardized incidence rates (ASIR) per 100,000 persons for the beginning (2005–2007) and the end (2017–2019) of the study period and estimated average annual percentage change.

Results

Data from 137,469 persons diagnosed with colorectal cancer were included. From 139,420 cases in total, 109,825 (78.8%) were adenocarcinomas (ACs), 2,800 (2.0%) were neuroendocrine neoplasms (NENs), and 26,795 (19.2%) had other histologies. This analysis showed a significant increase in the 3-year average annual ASIR of colorectal NENs in all age groups between 2005–2007 and 2017–2019 with the highest increase in the age groups 30–39 years (0.47 to 1.53 cases per 100,000 persons; +226%; p &lt; 0.05) and 20–29 years (0.52 to 1.38 cases per 100,000 persons; +165%; p &lt; 0.05). The increase was driven by appendiceal and rectal NENs but not by colonic NENs. The 3-year average annual ASIR of colorectal ACs did not change significantly for the age groups below 50 years. For those aged 50 years and above, the 3-year average annual ASIR of colorectal ACs decreased significantly (132.55 to 105.95 cases per 100,000 persons; −20%; p &lt; 0.05]). The proportion of NENs increased across all age groups, especially in the younger age groups.

Conclusion

Future studies that analyze trends in early-onset colorectal cancer need to distinguish between anatomic sites as well as histological subgroups and may, thus, provide useful information regarding the organization of colorectal cancer screening, which primarily helps to detect adenomas and adenocarcinomas."

Appendiceal sessile serrated lesions are distinct from their right-sided colonic counterparts and may be precursors for appendiceal mucinous neoplasms

Low-grade appendiceal mucinous neoplasms (LAMNs) can occur concurrently with appendiceal sessile serrated lesions (SSLs). To interrogate relatedness, we performed multigene and immunohistochemical characterizations of paired and unpaired SSLs and LAMNs. We evaluated 62 serrated lesions from 50 appendectomy specimens for hotspot mutations in BRAF, KRAS and GNAS genes. Cases were subdivided into 3 groups: 20 unpaired SSLs, 18 unpaired LAMNs, and 12 with an SSL and concurrent LAMN. β-catenin and Annexin A10 immunostaining were performed on the SSL and LAMN components in the 12 paired cases, and fourteen colonic SSLs served as controls. There was no significant difference in KRAS hotspot mutation rates in appendiceal SSLs (17/26; 65.4%) and LAMNs (16/30; 53.3%) (p=0.42). BRAF V600E was identified in a single case (1/50; 2.0%) of SSL and concurrent LAMN (p=1.0). Mutations in GNAS were more common in LAMNs (6/30; 20.0%) compared to SSLs (1/31; 3.2%) (p=0.05). The molecular genotypes between paired SSLs and LAMNs were concordant in most cases (10/12; 83.3%). Annexin A10 immunostaining was significantly greater in colonic SSLs (14/14; 100%) compared to appendiceal SSLs (1/12; 8.3%) (p<0.0001). β-catenin immunostaining was significantly increased in LAMNs (10/12; 83.3%) compared to their paired appendiceal SSLs (2/12; 16.7%)(p=0.003). Overall, appendiceal sessile serrated lesions are predominantly driven by KRAS mutations and are not characterized by Annexin A10 immunostaining. Our data suggests that at least a subset of LAMNs may arise from a precursor SSL in which GNAS mutations and/or upregulation of the WNT-signaling pathway are likely key events modulating this progression.

Clinicopathological Features of Low-Grade Appendiceal Mucinous Neoplasms Confined to the Appendix

OBJECTIVE

To investigate the clinicopathological features and follow-up of low-grade appendiceal mucinous neoplasms (LAMNs) confined to the appendix.

METHODS

The clinicopathological features, pathological primary tumor (pT) staging and follow-up of 22 patients with LAMNs confined to the appendix were analyzed retrospectively.

RESULTS

Of 22 patients with LAMNs, 14 were pTis (eight pTis^m and six pTis^f), six were pT3, and two were pT4a. The appendiceal diameter was significantly larger for pTis^f than for pTis^m. The interval between first symptoms and surgery was longer for pTis^f than for pTis^m, but not significantly different. No significant differences were found between the pT stages and appendiceal diameter or in the interval between the first symptoms and surgery. Pathomorphologically, the epithelial structures were mainly flat (100%), undulating or scalloped (82%); a few showed filiform villous hyperplasia (46%), and seven (32%) had serrated lesions in the background. Diverticula may be associated with LAMNs, and the location of acellular mucin caused by diverticula affected the pT stage of the LAMNs. The immunohistochemistry information showed the same pattern with cytokeratin 7 (CK7) negative, cytokeratin 20 (CK20) positive and caudal type homeobox 2 (CDX-2) positive. No lymph node metastasis was found. The lack of treatment guidelines for LAMNs confined to the appendix and different acceptances of patients of preventive intervention led to varied clinical treatments. However, we found no short-term benefits of prophylactic extended resection or hyperthermic intraperitoneal chemotherapy.

CONCLUSION

LAMNs confined to the appendix are rare and must be differentiated from serrated lesions and diverticula. LAMNs with different pT stages have inert biological behavior. Determining the long-term effects of preventive treatment on survival and recurrence requires more data and a longer follow-up.

Altered linkage pattern of N-glycan sialic acids in pseudomyxoma peritonei

Pseudomyxoma peritonei (PMP) is a highly mucinous adenocarcinoma growing in the peritoneal cavity and most commonly originating from the appendix. Glycans play an important role in carcinogenesis, and glycosylation is altered in malignant diseases, including PMP. We have previously demonstrated that fucosylation of N-glycans is increased in PMP, but we did not observe modulation of overall sialylation. As sialic acids can be attached to the rest of the glycan via α2,3- or α2,6-linkage, we have now analyzed the linkage patterns of sialic acids in tissue specimens of normal appendices, low-grade appendiceal mucinous neoplasms (LAMN), low-grade (LG) PMP and high-grade (HG) PMP. For the linkage analysis, the enzymatically released acidic N-glycans were first treated with ethyl esterification or α2,3-sialidase digestion followed by MALDI-TOF mass spectrometry. Significant increase in the relative abundance of α2,6-sialylated and decrease in α2,3-sialylated N-glycans was observed in PMP tumors as compared to the normal appendices (P < 0.025). More specifically, increased α2,6-sialylation (P < 0.05) and decreased α2,3-sialylation (P < 0.01) were detected in afucosylated and monofucosylated N-glycans of PMPs, whereas the less abundant multifucosylated glycans, containing terminal fucose, demonstrated increased α2,3-sialylation (P < 0.01). Importantly, the increase in α2,6-sialylation was also detected between PMP and the appendiceal precursor lesion LAMN (P < 0.01). The identified glycosylation alterations produce ligands for sialic acid-binding immunoglobulin-like lectins (Siglecs) and sialofucosylated glycans binding selectins, which play a role in the peritoneal dissemination and progression of the disease.