Low-grade Mucinous Neoplasm Research Articles

Surgical overtreatment of pancreatic intraductal papillary mucinous neoplasms: Do the 2017 International Consensus Guidelines improve clinical decision making?

BackgroundSignificant overtreatment of intraductal papillary mucinous neoplasms can be attributed to low specificity of the current International Consensus Guidelines as well as nonconformity with the guidelines. We compare the ability of the 2012 and revised 2017 intraductal papillary mucinous neoplasms International Consensus Guidelines to predict high-grade dysplasia/invasive cancer and to determine the preoperative variables that predict resection of benign or low-grade dysplasia in tertiary care centers. MethodsClinical, radiographic, and pathologic data for resected intraductal papillary mucinous neoplasms at 3 high-volume National Cancer Institute Cancer Centers were reviewed and the 2012 and 2017 consensus criteria were retrospectively applied. When International Consensus Guidelines were not met, clinical decision analysis was used to determine the primary indication for resection. Logistic regression identified variables associated with pathologic grade. ResultsRecords for a total of 251 patients were reviewed, 129 of whom (52%) had low-grade dysplasia. The revised 2017 International Consensus Guidelines had high sensitivity (98.4%) and negative predicted value (96.1%), and all high-risk stigmata predicted high-grade dysplasia/invasive cancer; however, specificity remained low (14.8%). Nonconformity with International Consensus Guidelines was the most powerful predictor of low-grade dysplasia on final pathologic examination (9.5; 2.12–40.78). Independent predictors of low-grade dysplasia included age younger than 50 (2.46; 1.08–5.62), fine-needle aspiration without epithelial cells (2.6; 1.43–4.72), and normal duct diameter (3.07; 1.99–4.75). Diabetes developed in 30% of patients after resection. ConclusionManagement of intraductal papillary mucinous neoplasms remains clinically challenging. Low specificity of the International Consensus Guidelines and nonconformity with the guidelines continue to contribute to unnecessary pancreatic resections. Improved tools for disease classification as well as a better understanding of the natural history, biology, and rates of progression of intraductal papillary mucinous neoplasms are needed to avoid surgical overtreatment of low-grade intraductal papillary mucinous neoplasms.

Coexistence of low-grade mucinous neoplasm and carcinoid (collision tumor) within multiple appendiceal diverticula: A case report.

Neoplasms of the appendix are very rare. They usually show glandular or neuroendocrine differentiation, and when they both occur in the same area, it is called a "collision tumor." Low-grade mucinous neoplasms associated with appendiceal diverticula are also uncommon. The appendectomy specimen of a 60-year-old man contained dense and mucoid luminal content on the distal tip, and similarly a solid, yellow, lumen-obscuring tumor with a diameter of 1.5 cm at the base of the appendix was detected. Microscopically, there were three diverticula that comprised herniation of the mucosal layer through the appendiceal wall. Interestingly, all of the diverticula and the normal-appearing appendiceal wall were lined by adenomatous epithelium. The luminal portion had pools of mucin-containing, rare clusters of low-grade epithelium that gave rise to the diagnosis of a "low-grade mucinous neoplasm." The solid-appearing tumor was diagnosed as a "neuroendocrine neoplasm," and there was no transition zone between these two types of tumors. There are some cases that have been reported as low-grade mucinous neoplasms associated with appendicular diverticula and collision tumors consisting both mucinous neoplasms and carcinoid tumors in the literature; our case has a unique appearance with two different types of tumors both in the appendix wall and within multiple diverticula.

Unusual Histopathological Findings in Appendectomy Specimens: A Retrospective Analysis of 2047 Cases.

In this study, we retrospectively evaluated cases of patients who had undergone appendectomy in our hospital and aimed to present the efficiency of diagnostic tests and demographic data of cases. Pathological reports were analyzed for the following parameters: age, gender, and pathological diagnosis. In addition, the demographic and clinicopathologic characteristics of patients with unusual histopathologic findings were evaluated in detail, and reanalysis of archived resected appendix specimens was carried out. Files of 2047 patients (1329 males, 718 females, sex ratio: 1.85, age range: 1-87 years, mean age: 26, 50 years), who had been operated with a diagnosis of acute appendicitis in the emergency department of Bezmialem Vakıf University Medical Faculty from November 2011 to June 2014, were retrospectively evaluated. Cases were separated into 2 groups. Cases with histopathologic examination reported as acute appendicitis constituted group 1 (n = 2013, 98.34%), and cases with pathologic findings other than acute appendicitis constituted group 2 (n = 34, 1.66%). The second group consisted of 8 low-grade mucinous neoplasms, 7 mucoceles, 6 carcinoid, 5 granulomatous inflammation, 4 intraluminal Enterobius vermicularis, 1 endometriosis externa, 1 adenocarcinoma infiltrated to serosa, 1 mesenteric cyst, and 1 low-grade adenocarcinoma formed in mucinous cystic neoplasm background. Acute appendicitis is the most common emergency surgical condition. Although most of the resected appendectomy specimens showed typical histopathologic findings, some (1.66%) showed unusual histopathologic findings. Even if the macroscopic appearance of the specimen is normal or acute appendicitis, we suggest routine histopathological examination.

Quantitative proteomic analysis of pancreatic cyst fluid proteins associated with malignancy in intraductal papillary mucinous neoplasms

BackgroundThe application of advanced imaging technologies for identifying pancreatic cysts has become widespread. However, accurately differentiating between low-grade dysplasia (LGD), high-grade dysplasia (HGD), and invasive intraductal papillary mucinous neoplasms (IPMNs) remains a diagnostic challenge with current biomarkers, necessitating the development of novel biomarkers that can distinguish IPMN malignancy.MethodsCyst fluid samples were collected from nine IPMN patients (3 LGD, 3 HGD, and 3 invasive IPMN) during their pancreatectomies. An integrated proteomics approach that combines filter-aided sample preparation, stage tip-based high-pH fractionation, and high-resolution MS was applied to acquire in-depth proteomic data of pancreatic cyst fluid and discover marker candidates for IPMN malignancy. Biological processes of differentially expressed proteins that are related to pancreatic cysts and aggressive malignancy were analyzed using bioinformatics tools such as gene ontology analysis and Ingenuity pathway analysis. In order to confirm the validity of the marker candidates, 19 cyst fluid samples were analyzed by western blot.ResultsA dataset of 2992 proteins was constructed from pancreatic cyst fluid samples. A subsequent analysis found 2963 identified proteins in individual samples, 2837 of which were quantifiable. Differentially expressed proteins between histological grades of IPMN were associated with pancreatic diseases and malignancy according to ingenuity pathway analysis. Eighteen biomarker candidates that were differentially expressed across IPMN histological grades were discovered—7 DEPs that were upregulated and 11 that were downregulated in more malignant grades. HOOK1 and PTPN6 were validated by western blot in an independent cohort, the results of which were consistent with our proteomic data.ConclusionsThis study demonstrates that novel biomarker candidates for IPMN malignancy can be discovered through proteomic analysis of pancreatic cyst fluid.

A case of mature cystic teratoma with intestinal structures harboring intestinal-type low-grade mucinous neoplasm

The formation of gastrointestinal-type epithelium is found in 7–13% of mature cystic teratomas, which are the most common germ cell tumors of the ovary. Few cases harboring organized gastrointestinal tract formation have been reported, and a mucinous neoplasm arising in them is further rare. Here, we report a case of an ovarian mature cystic teratoma with intestinal structures harboring intestinal-type mucinous neoplasm, mimicking low-grade appendiceal mucinous cystadenoma. A 66-year-old female, with remarkably increased serum carcinoembryonic antigen (CEA) level, underwent total abdominal hysterectomy and bilateral salpingo-oophorectomy due to the ovarian tumor. The immunoprofile of the tumor showed CK7−/CK20+. We review the past literatures, and then consider that the existence of mucinous neoplasm should be kept in mind if we find elevated level of serum CEA and the organized gastrointestinal development in an ovary. The immunoprofile of CK7/CK20 is useful to determine the origin of mucinous tumors associated with mature cystic teratomas.

Appendiceal collision tumour – A case report

Collision tumours are uncommon occurrences, but they have been reported in various locations. This case report describes a patient who underwent an elective appendicectomy for a ‘mucoid neoplasm of the appendix’ discovered incidentally on abdominal imaging. Histology showed a low grade mucinous neoplasm of the appendix with a concurrent well-differentiated neuroendocrine tumour.

330 Low-Grade Mucinous Neoplasm of the Appendix in the Setting of a CDKN2A Gene Mutation: A Potential Association Risk Factor

330 Low-Grade Mucinous Neoplasm of the Appendix in the Setting of a CDKN2A Gene Mutation: A Potential Association Risk Factor

Incidental appendectomy during robotic laparoscopic prostatectomy-safe and worth to perform?

The purpose of this study is to investigate the safety and patients' benefit of incidental appendectomy during robot-assisted laparoscopic radical prostatectomy (RALRP). Fifty-three patients, who had incidental appendectomy during RALRP between January 2012 and March 2014, were enrolled to this study. To evaluate the safety of the procedure, following parameters were evaluated: patient age, duration of surgery, perioperative complications (classified by Clavien-Dindo), time to bowel movement, and length of hospital stay. Furthermore, intraoperative visual appearance, location, and histopathological evaluation of the appendix were evaluated. Data was analyzed by descriptive statistics. Mean age of patients was 61years, the average hospital stay 5days. No perioperative complications occurred. The appendix was unsuspicious in 39 patients (73.6%); 14 patients (26.4%) had macroscopically signs of inflammation. Of the 53 resected appendixes, the histopathological evaluation showed 33 (62.2%) inconspicuous appendices, 11 (20.8%) post-inflammatory changes, 4 (7.5%) with chronical signs of inflammation and 3 (5.7%) with signs of acute inflammation. In 2 patients (3.8%), low-grade mucinous neoplasms were found in the specimens. Incidental appendectomy during RALRP is a feasible procedure. With regard to inflammation and neoplastic changes, incidental appendectomy can be considered for patients scheduled for robot-assisted prostate surgery.

DNA Cytometry for Differentiation Between Low- and Medium-grade Dysplasia in Intraductal Papillary Mucinous Neoplasms.

The indication for resection of cystic pancreatic lesions is usually performed by sectional imaging criteria, such as the Sendai criteria. The aim of this study was to analyze a possible correlation between DNA cytometry and Sendai criteria for the differentiation between low-grade intraductal papillary mucinous neoplasms (IPMN-A) and medium-grade dysplasia (IPMN-B). Histopathological analysis, DNA index and preoperative Sendai criteria were determined in 16 patients who underwent pancreatic resection for IPMN. All patients with IPMN-B showed aneuploid histograms with DNA indices ≥1.3, whereas three out of four patients with IPMN-A had diploid DNA indices ≤1.3. All 11 patients with one or more high-risk stigmata and aneuploid histograms had IPMN-Bs, whereas both patients who were Sendai-negative and diploid in the DNA analysis had an IPMN-A. DNA index may be an important diagnostic tool for the differentiation of different IPMN types beyond the traditional Sendai criteria.

Challenges Diagnosing Appendiceal Neoplasms during Pregnancy

A 31 y.o. G1P0 at 18 weeks estimated gestational age was found to have an echogenic 7.8 cm by 3.1 cm mass adjacent to the uterine fundus during an anatomy scan. Follow-up radiology performed abdominal ultrasound was normal. Patient delivered vaginally without incident. Three years later she was diagnosed with a right complex pelvic mass identified during a saline infusion sonogram for fertility evaluation. Carcinoembryonic antigen was elevated. Laparoscopic surgery revealed appendiceal mass and normal gynecological findings. Pathology demonstrated low grade mucinous neoplasm of the appendix.

Invasive Moderately-Differentiated Mucinous Adenocarcinoma Incidentally Identified in Perforated Acute Diverticulitis With Abscess Formation

Colonic adenocarcinoma rarely arises within a diverticulum. As illustrated in this case report, such an occurrence presents difficulties in diagnosis, posed by the overlap of radiological findings in diverticulitis and adenocarcinoma and the potential absence of luminal lesion. Here we present a 77-year-old male with acute left lower abdominal pain, fever and leukocytosis. Computarized tomography (CT) imaging revealed extensive colonic diverticulosis, with sigmoid colon wall thickening, extraluminal air and a pericolic abscess. No enlarged lymph nodes were detected. The clinical diagnosis was acute sigmoid diverticulitis with micro-perforation and abscess formation. Partial sigmoidectomy was performed and diverticulitis confirmed; no tumor was identified in the resected colon. However, fragments of mucinous adenocarcinoma were incidentally recognized in the pericolic abscess contents. Immunohistochemical (IHC) studies supported a primary colonic adenocarcinoma, warranting further clinical workup. A subsequent distal sigmoidectomy revealed moderately-differentiated mucinous adenocarcinoma invading through the visceral peritoneum, and arising in a low-grade mucinous neoplasm within a diverticulum. The case illustrates that in a patient with diverticulitis and no evidence of a luminal neoplasm, the unexpected finding of adenocarcinoma in the resected bowel may be attributable to adenocarcinoma arising within a diverticulum.

Pediatric mucinous neoplasm of the appendix presenting as a mucocele: A case report and review of the literature

Mucocele of the appendix is a rare entity in pediatrics, with few case reports in the literature. We present a case of a 17-year-old male with right lower quadrant pain who was found to have an appendiceal mucocele while being evaluated for appendicitis. Laparoscopic-assisted resection was performed, with pathology confirming a low-grade mucinous neoplasm of the appendix, a tumor scarcely described in the pediatric population. He underwent complete resection with negative margins, rendering him cured without the need for any further resection or treatment. We review the literature on this topic.

A giant mucinous cystadenocarcinoma of the appendix: a case report and review of the literature

BackgroundMucinous cystadenocarcinoma is the second most common etiology of appendiceal mucocele. We report a relatively rare case of a giant appendiceal mucocele caused by mucinous cystadenocarcinoma, which occupied the entire abdomen of an adult woman.Case presentationA 63-year-old woman presented with a chief complaint of abdominal distention. Imaging studies showed a giant cystic mass occupying her entire abdomen. Laparotomy confirmed a giant appendiceal mucocele, and the patient underwent ileocecal resection. A mucinous deposit was not found in her abdominal cavity, and the ovaries were grossly normal bilaterally. The pathological diagnosis was mucinous adenocarcinoma with a low-grade mucinous neoplasm that invaded the subserosa. Regional lymph node metastasis was not found. She has had recurrence-free survival for 5 years.ConclusionsThe present case is the largest appendiceal cystadenocarcinoma ever reported. The optimal treatment of an appendiceal neoplasm requires further research based on consensus terminology of an appendiceal mucocele.

SATB2 Expression Distinguishes Ovarian Metastases of Colorectal and Appendiceal Origin From Primary Ovarian Tumors of Mucinous or Endometrioid Type.

The primary origin of some ovarian mucinous tumors may be challenging to determine, because some metastases of extraovarian origin may exhibit gross, microscopic, and immunohistochemical features that are shared by some primary ovarian mucinous tumors. Metastases of primary colorectal, appendiceal, gastric, pancreatic, and endocervical adenocarcinomas may simulate primary ovarian mucinous cystadenoma, mucinous borderline tumor, or mucinous adenocarcinoma. Recently, immunohistochemical expression of SATB2, a transcriptional regulator involved in osteoblastic and neuronal differentiation, has been shown to be a highly sensitive marker of normal colorectal epithelium and of colorectal adenocarcinoma. SATB2 expression has not been reported in normal epithelium of the female reproductive tract. Therefore, we hypothesized that SATB2 may be of value in distinguishing ovarian metastases of colorectal adenocarcinoma from primary ovarian mucinous tumors and from primary ovarian endometrioid tumors. Among primary ovarian tumors, SATB2 staining was observed in 0/22 mucinous cystadenomas that lacked a component of mature teratoma, 4/12 mucinous cystadenomas with mature teratoma, 1/60 mucinous borderline tumors, 0/17 mucinous adenocarcinomas, 0/3 endometrioid borderline tumors, and 0/72 endometrioid adenocarcinomas. Among ovarian metastases, SATB2 staining was observed in 24/32 (75%) colorectal adenocarcinomas; 8/10 (80%) low-grade appendiceal mucinous neoplasms; and 4/4 (100%) high-grade appendiceal adenocarcinomas. No SATB2 staining was observed in any ovarian metastasis of pancreatic, gastric, gallbladder, or endocervical origin. Evaluation of primary extraovarian tumors showed the highest incidences of SATB2 staining among primary colorectal adenocarcinomas (71%), primary appendiceal low-grade mucinous neoplasms (100%), and primary appendiceal high-grade adenocarcinomas (100%). Similar to their metastatic counterparts, none of the primary pancreatic or gastric adenocarcinomas showed any SATB2 staining. In a subset of tumors for which CK7, CK20, and CDX2 were available, SATB2 was never positive in any tumor of any origin that was CK7+CK20-CDX2-. Among tumors that coexpressed all 3 markers (CK7+CK20+CDX2+), 6/7 SATB2 tumors were of colorectal or appendiceal origin, and 1/7 was a primary ovarian borderline tumor. We conclude that ovarian tumors with mucinous or endometrioid features that express SATB2 are unlikely to be of primary ovarian origin unless there is a component of mature teratoma in the ovary; instead, attention should be directed to a colorectal or appendiceal origin. SATB2 may be of particular value in ovarian mucinous tumors that are positive for all 3 markers (CK7+CK20+CDX2+), as SATB2 staining strongly implicates a colorectal or appendiceal origin.

The relationship between diverticula and low-grade mucinous neoplasm of the appendix. Does the diverticulum play a role in the development of periappendicular mucin deposition or pseudomyxoma peritonei?

Prevalences of diverticulum and low-grade mucinous neoplasm (LGMN) were reported as 0.04-2% and less than 1% in the appendix. In this study, the frequency of diverticulum in LGMN cases, the relationship between diverticula and periappendicular mucin, and the possible role of diverticula in pseudomyxoma peritonei pathogenesis were researched. Through systematic review and targeted search, 38 LGMN and 96 diverticula were identified, frequencies and relationship between diverticulum and LGMN were analysed. Diverticulum and LGMN were determined in 4.8% and 1.04%, respectively, of 1922 appendectomy materials specifically grossed by the same pathologist. The prevalence of diverticulum was higher in our study than literature. The difference may be due to detailed macroscopic examination. Diverticulum was detected in 60% of LGMN cases. The rate of diverticulum was found to be significantly higher in LGMNs than non-neoplastic diverticulum (p < 0.001). Periappendicular mucin deposition was significantly more frequent in LGMN cases with diverticulum than in other groups (p < 0.05). Follow-ups were available in 18 patients; none of them had mucin deposition in the peritoneal cavity. We detected that periappendicular mucin was highly associated with diverticula in LGMN cases. Periappendicular acellular mucin deposition may not give rise to pseudomyxoma peritonei. We may think that mucin could move out of the appendix through the diverticulum rather than neoplastic spread in some of these cases.

The Role of Heated Intraperitoneal Chemotherapy (HIPEC) in Low-Grade Appendiceal Neoplasm: Friend or Foe?

Low-grade mucinous appendiceal neoplasms are rare tumors. There is limited data on the treatment for pseudomyxoma peritonei with low-grade appendiceal histology. Classifications of appendiceal neoplasms include low-grade appendiceal mucinous neoplasm (LAMN), diffuse peritoneal adenomucinosis (DPAM), and peritoneal mucinous carcinomatosis (PMCA). Studies have demonstrated patients with low-grade appendiceal neoplasms have improved overall survival compared to patients with high-grade appendiceal neoplasms. Since low-grade tumors have better prognosis some retrospective trials have suggested observation in patients with these types of tumors. Another option includes cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (HIPEC). We have done an extensive literature search exploring the various methods in which to treat patients with this disease.

Appendiceal mucocele due to mucinous adenoma diagnosed by computed tomography colonography.

An asymptomatic 50-year-old man underwent a low-dose computed tomography colonography (CTC) for screening purpose. The CTC examination was negative for colonic mass or polyps, but axial and coronal two-dimensional CTC images (Fig. 1) showed a large elongated low-attenuation mass in the expected region of the appendix, in line with an appendiceal mucocele. Three-dimensional CTC endoluminal images (Fig. 2) showed the mass bulging into the cecal lumen. The patient underwent appendectomy with partial right hemicolectomy and is in good health. Pathology confirmed an appendiceal mucocele from mucinous adenoma, and in particular the histological examination revealed a low-grade mucinous appendiceal neoplasm with negative regional lymph nodes and with no signs of mucinous peritoneal carcinomatosis. This case shows the crucial role of CTC in the diagnosis of an unknown submucosal disease [1], potentially malignant if not early diagnosed [2,3]; that diagnosis would not have been made if the patient had had an optical colonoscopy or a double contrast barium enema instead of CTC, since both tests fail to evaluate extraluminal areas.

Diagnosis and Treatment of Mucinous Appendiceal Neoplasm Presented as Acute Appendicitis.

Appendiceal mucocele is a rare cause of acute abdomen. Mucinous appendiceal neoplasms represent 0.2–0.7% of all appendix specimens. The aim of this study is to report a case of a mucinous appendiceal neoplasm presented as acute appendicitis, discussing the clinical and surgical approach in the emergency setting. A 72-year-old female patient was admitted to the emergency department with a clinical examination indicative of acute abdomen. The patient underwent abdominal computed tomography scan which revealed a cystic lesion in the right iliac fossa measuring 8.3 × 5.2 × 4.1 cm, with calcified walls, and a mean density indicative of high protein content. The patient was taken to the operating room and a right hemicolectomy was performed. The postoperative course was unremarkable. The histopathological examination revealed a low-grade mucinous appendiceal neoplasm with negative regional lymph nodes. Ultrasound and CT are useful in diagnosing appendiceal mucocele and synchronous cancers in the emergency setting. The initial operation should include appendectomy and resection of the appendicular mesenteric fat along with any fluid collection for cytologic examination. During urgent appendectomy it is important to consider every mucocele as malignant in order to avoid iatrogenic perforation causing pseudomyxoma peritonei. Although laparotomy is recommended, the laparoscopic approach is not contraindicated.

Covering the Cover

Covering the Cover

Ovarian seromucinous carcinoma: report of a series of a newly categorized and uncommon neoplasm.

Seromucinous neoplasms are a new category of ovarian epithelial tumor in the revised World Health Organization Classification of Tumours of the Female Reproductive Organs. Borderline variants are well described, but there have been few reports of seromucinous carcinomas. We report the clinicopathologic features in 19 cases of ovarian seromucinous carcinoma in patients aged 16 to 79 years (mean 47). In 16 cases, the neoplasm was unilateral and in 3 cases bilateral. The tumors ranged in size from 1.8 to 18 cm (mean 10.5 cm). The tumors were stage I (n=15), stage II (n=1), and stage III (n=3). The histologic features were highly variable both within and between individual tumors. The majority of neoplasms (12 cases) exhibited a predominant papillary architecture with lesser components of glandular, microglandular, and solid growth. A predominant glandular architecture was present in 6 cases, whereas 1 had a predominantly solid growth. A characteristic feature was an admixture of cell types. Most of the tumors (15 cases) were mainly composed of endocervical-like mucinous cells, whereas in 4 cases there was predominant endometrioid differentiation. Other cell types, present in varying proportions, included hobnail cells, eosinophilic cells, squamous cells, clear cells, and signet-ring cells. An infiltrate of neutrophil polymorphs was a prominent feature in most cases. Most cases also exhibited areas of microglandular architecture with cytoplasmic clearing and intraluminal polymorphs, the features closely resembling cervical microglandular hyperplasia. Areas of stromal hyalinization, adenofibromatous growth, and psammoma bodies were present in a minority of cases. Endometriosis was identified in the same ovary in 10 cases, and in 10 there was a component of seromucinous borderline tumor. Thirteen, 5, and 1 tumor were of grades 1, 2, and 3, respectively (using the FIGO grading system for endometrioid adenocarcinomas of the uterine corpus). A synchronous uterine endometrioid adenocarcinoma was present in 1 case. Immunohistochemically, there was positive staining with CK7 (17/17 cases), estrogen receptor (16/16 cases), progesterone receptor (6/7 cases), CA125 (15/15 cases), PAX8 (8/8 cases), CEA (8/13 cases), CA19.9 (8/9 cases), and WT1 (2/13 cases). CK20 and CDX2 were negative in all cases tested (16 and 14, respectively). p53 showed "wild-type" staining in 4/4 cases, and p16 was focally positive in 5/5 cases. Follow-up information was available in 8 patients. Seven were alive with no evidence of disease (follow-up 3 to 74 mo), whereas 1 patient who initially presented with a stage IIB tumor died of disease at 192 months. Given the characteristic admixture of cell types and the overlapping morphologic features with low-grade serous, mucinous, and endometrioid neoplasms, the most appropriate categorization of seromucinous carcinomas is uncertain, but we believe they are best regarded as a distinct type of ovarian epithelial malignancy and are most similar to endometrioid adenocarcinomas. We recommend grading them in an analogous manner to ovarian endometrioid adenocarcinomas.