Mural Intracholecystic Neoplasms Arising in Adenomyomatous Nodules of the Gallbladder: An Analysis of 19 Examples of a Clinicopathologically Distinct Entity

Adenomyoma/adenomyomatosis-associated mural intracholecystic neoplasms: analysis of clinico-pathologic, imaging, and molecular features of a consecutive case series

Adenomyoma/adenomyomatosis (AM) of the gallbladder is generally considered an incidental and innocuous finding; however, neoplastic lesions, including intracholecystic neoplasms (ICNs), flat-type dysplasia, and carcinomas, may arise within AM. AM-associated ICNs, composed of mural cystically dilated glands containing florid papillary proliferations lined by mucinous and/or overtly dysplastic epithelium, are very rare and poorly characterized. This study aimed at investigating the clinico-radiologic, phenotypic/immunophenotypic, and molecular features of a mono-institutional case series of four AM-ICNs (0.2% of cholecystectomies). Immunohistochemistry for CDX2, MUC2, MUC5AC, MUC6, MUC1, HER2, ß-catenin, and p53, as well as next-generation sequencing of 110 tumor-related genes (AmoyDx® Comprehensive Panel), were performed. Our study confirms the AM-ICN-associated clinico-demographic characteristics previously described, including the relatively low frequency of associated invasive carcinoma (one case, 25%), although high-grade dysplasia (HGD) was observed in three out of four cases. In two cases, imaging findings suspicious for neoplasm were seen. Segmental-type AM was seen in two cases. Predominantly cell phenotype was gastric foveolar in two AM-ICNs and pancreatobiliary in the other two cases (both with HGD), while the immunophenotype was hybrid/mixed in all cases. No case had nuclear ß-catenin expression nor Wnt pathway or KRAS gene alterations. One case showed both HER2 point mutation and HER2 amplification, while the AM-ICN associated with an invasive adenocarcinoma harbored TP53 mutation and p53 overexpression. In conclusion, our findings suggest the separation of AM-ICNs from other gallbladder dysplastic lesions.

Interpretation, Reporting, Imaging-Based Workups, and Surveillance of Incidentally Detected Gallbladder Polyps and Gallbladder Wall Thickening: 2025 Recommendations From the Korean Society of Abdominal Radiology

Incidentally detected gallbladder polyps (GBPs) and gallbladder wall thickening (GBWT) are frequently encountered in clinical practice. However, characterizing GBPs and GBWT in asymptomatic patients can be challenging and may result in overtreatment, including unnecessary follow-ups or surgeries. The Korean Society of Abdominal Radiology (KSAR) Clinical Practice Guideline Committee has developed expert recommendations that focus on standardized imaging interpretation and follow-up strategies for both GBPs and GBWT, with support from the Korean Society of Radiology and KSAR. These guidelines, which address 24 key questions, aim to standardize the approach for the interpretation of imaging findings, reporting, imaging-based workups, and surveillance of incidentally detected GBPs and GBWT. This recommendation promotes evidence-based practice, facilitates communication between radiologists and referring physicians, and reduces unnecessary interventions.

Detached pyloric gland adenoma of gallbladder: A case report and review of literature

Key Clinical Message

Vigilant intraoperative inspection is crucial during gallbladder surgery to detect any abnormal tissue including the rare pyloric gland adenomas, which can be easily missed. Thorough examination and removal of unusual lymph nodes or thickened tissues are essential to prevent the risk of malignant transformation and ensure comprehensive patient care.

Abstract

Pyloric gland adenomas are uncommon tumors that can be discovered in various organs such as the stomach, gallbladder, and pancreas. Typically lacking noticeable symptoms, these tumors are categorized into subtypes, with the pyloric variant being the most frequent. The term "intracholecystic papillary-tubular neoplasms (ICPN)" is used to emphasize growth patterns and associated risks. In a discussed case, a detached pyloric gland adenoma was identified incidentally during a cholecystectomy procedure. A 58-year-old obese male presented with upper abdominal pain, nausea, and vomiting. He was diagnosed with early cholecystitis caused by gallstones. Subsequently, during a laparoscopic cholecystectomy, a detached adenoma was discovered. Vigilant screening is crucial, as the identification of gallbladder pyloric gland adenomas is a rare occurrence that might be missed during gallbladder surgery. Any unusual lymph nodes or thickened tissues found in association with the gallbladder ought to be carefully removed, as they could potentially indicate detached gallbladder adenomas with a significant risk of becoming malignant. Failing to consider this possibility may subject the patient to prolonged risks if not meticulously examined.

Diffuse Adenomyomatosis of Gallbladder: A Rare Case Report With Insights Into a Distinctive Condition

Gallbladder adenomyoma/adenomyomatous nodule/adenomyomatosis is a benign condition characterized by mucosal invaginations within the gallbladder wall with or without proliferation of smooth muscle fibers. Gallbladder adenomyoma is often asymptomatic and discovered incidentally during imaging studies performed for other unrelated conditions. It can mimic malignancy on radiological findings, creating a diagnostic dilemma. The management and outcome of adenomyoma and malignant lesions of gallbladder are completely different. We present here a rare case of 52-year-old female diagnosed with gallbladder adenomyoma in histopathological examination highlighting the insights into this benign distinctive condition. Therefore, it is essential to completely understand the pathognomonic and histopathological features of gallbladder adenomyoma in order to accurately diagnose this condition.

TPPP-BRD9 fusion-related gallbladder carcinomas are frequently associated with intracholecystic neoplasia, neuroendocrine carcinoma, and a distinctive small tubular-type adenocarcinoma commonly accompanied with a syringomatous pattern

A fusion between tubulin polymerization-promoting protein (TPPP), a regulatory cytoskeletal gene, and the chromatin remodeling factor, bromodomain-containing protein 9 (BRD9), TPPP-BRD9 fusion has been found in rare cancer cases, including lung and gallbladder cancers (GBC). In this study, we investigated the histopathological features of 16 GBCs previously shown by RNA sequencing to harbor the TPPP-BRD9 fusion. Findings in the fusion-positive GBCs were compared with 645 GBC cases from the authors' database. Among the 16 TPPP-BRD9 fusion-positive GBC cases, most were females (F:M = 7:1) of Chinese ethnicity (12/16), whereas the remaining cases were from Chile. The histopathological examination showed the following findings: 1) Intracholecystic neoplasm (ICN) in 7/15 (47% vs. 7% 645 reference GBCs, p < 0.001), all with gastro-pancreatobiliary phenotype, often with clear cell change, and in the background of pyloric gland metaplasia and extensive high-grade dysplasia. 2) Neuroendocrine carcinoma (NEC) morphology: 3 cases (27% vs. 4.6% in the reference database, p = 0.001) showed a sheet-like and nested/trabecular growth pattern of monotonous cells with salt-and-pepper chromatin characteristic of NECs. Two were large cell type, one had prominent clear cell features, a rare finding in GBNECs; the other one had relatively bland, well-differentiated morphology, and the remaining case was small cell type. 3) Adenocarcinoma identified in 8 cases had a distinctive pattern characterized by widely separated small, round tubular units with relatively uniform nuclei in a fashion seen in mesonephric adenocarcinomas, including hobnail-like arrangement and apical snouts, reminiscent of tubular carcinomas of the breast in many areas. In some foci, the epithelium was attenuated, and glands were elongated, some with comma shapes, which along with the mucinous/necrotic intraluminal debris created a "syringoid" appearance. 4) Other occasional patterns included the cribriform, glomeruloid patterns, and metaplastic tubular-spindle cell pattern accompanied by hemorrhage. In conclusion, TPPP-BRD9 fusion-positive GBCs often develop through intracholecystic neoplasms (adenoma-carcinoma sequence) of gastro-pancreatobiliary lineage, appear more prone to form NEC morphology and have a propensity to display clear cell change. Invasive adenocarcinomas arising in this setting often seem to display a distinctive appearance that we tentatively propose as the TPPP-BRD9 fusion-positive pattern of GBC.

Dysplasia and Early Carcinoma of the Gallbladder and Bile Ducts: Terminology, Classification, and Significance

Most precursor lesions and early cancerous changes in the gallbladder and bile ducts present as clinically/grossly inapparent lesions. Low-grade dysplasia is difficult to define and clinically inconsequential by itself; however, extra sampling is required to exclude accompanying significant lesions. For high-grade dysplasia ('carcinoma in situ'), a complete sampling is necessary to rule out invasion. Tumoral intramucosal neoplasms (ie, intracholecystic and intraductal neoplasia) form radiologically/grossly visible masses, and they account for (present in the background of) about 5% to 10% of invasive cancers of the region. These reveal a spectrum of papilla/tubule formation, cell lineages, and dysplastic transformation. Some subtypes such as intracholecystic tubular non-mucinous neoplasm of the gallbladder (almost never invasive) and intraductal oncocytic or intraductal tubulopapillary neoplasms of the bile ducts (may have a protracted clinical course even when invasive) are to be noted separately. Other types of intracholecystic/intraductal neoplasia have a high frequency of invasive carcinoma and progressive behavior, which often culminates in mortality.

Adenomyomas of the Gallbladder: An Analysis of Frequency, Clinicopathologic Associations, and Relationship to Carcinoma of a Malformative Lesion

CONTEXT.—

The nature and associations of gallbladder (GB) "adenomyoma" (AM) remain controversial. Some studies have attributed up to 26% of GB carcinoma to AMs.

OBJECTIVE.—

To examine the true frequency, clinicopathologic characteristics, and neoplastic changes in GB AM.

DESIGN.—

Cholecystectomy cohorts analyzed were 1953 consecutive cases, prospectively with specific attention to AM; 2347 consecutive archival cases; 203 totally embedded GBs; 207 GBs with carcinoma; and archival search of institutions for all cases diagnosed as AM.

RESULTS.—

Frequency of AM was 9.3% (19 of 203) in totally submitted cases but 3.3% (77 of 2347) in routinely sampled archival tissue. A total of 283 AMs were identified, with a female to male ratio = 1.9 (177:94) and mean size = 1.3 cm (range, 0.3-5.9). Most (96%, 203 of 210) were fundic, with formed nodular trabeculated submucosal thickening, and were difficult to appreciate from the mucosal surface. Four of 257 were multifocal (1.6%), and 3 of 257 (1.2%) were extensive ("adenomyomatosis"). Dilated glands (up to 14 mm), often radially converging to a point in the mucosa, were typical. Muscle was often minimal, confined to the upper segment. Nine of 225 (4%) revealed features of a duplication. No specific associations with inflammation, cholesterolosis, intestinal metaplasia, or thickening of the uninvolved GB wall were identified. Neoplastic change arising in AM was seen in 9.9% (28 of 283). Sixteen of 283 (5.6%) had mural intracholecystic neoplasm; 7 of 283 (2.5%) had flat-type high-grade dysplasia/carcinoma in situ. Thirteen of 283 cases had both AM and invasive carcinoma (4.6%), but in only 5 of 283 (1.8%), carcinoma arose from AM (invasion was confined to AM, and dysplasia was predominantly in AM).

CONCLUSIONS.—

AMs have all the features of a malformative developmental lesion, and may not show a significant muscle component (ie, the name "adeno-myoma" is partly a misnomer). While most are innocuous, some pathologies may arise in AMs, including intracholecystic neoplasms, flat-type high-grade dysplasia or carcinoma in situ, and invasive carcinoma (1.8%, 5 of 283). It is recommended that gross examination of GBs include serial slicing of the fundus for AM detection and total submission if one is found.

Magnetic Resonance Diffusion-Weighted Imaging for Detecting Fundal Intracholecystic Papillary Neoplasm inside Rokitansky-Aschoff Sinuses: A Comparison of Two Cases and a Literature Review

Rokitansky-Aschoff sinuses (RAS) are a common imaging finding in gallbladder adenomyomatosis (ADM), often presenting as fundal cystic spaces. Intracholecystic papillary neoplasm (ICPN) is a relatively uncommon pre-invasive tumor of the gallbladder epithelium that rarely involves RAS mucosa. We compare two cases that showed similar fundal cystic spaces resembling RAS, in which Magnetic Resonance Diffusion-Weighted Imaging (MR-DWI) was valuable for detecting (or ruling out) an underlying malignant ICPN. Evidence from the literature overall supports the role of MR-DWI for detecting intracholecystic malignant tissue.

Dysplasia and carcinoma of the gallbladder: pathological evaluation, sampling, differential diagnosis and clinical implications

Pathological evaluation of gallbladder neoplasia remains a challenge. A significant proportion of cases presents as clinically and grossly inapparent lesions, and grossing protocols are not well established. Among epithelial alterations, pseudo-pyloric gland metaplasia is ubiquitous and of no apparent consequence, whereas goblet cell metaplasia and a foveolar change in surface cells require closer attention. Low-grade dysplasia is difficult to objectively define and appears to be clinically inconsequential by itself; however, extra sampling is required to exclude the possibility of accompanying more significant lesions. For high-grade dysplasia ('high-grade BilIN', also known as 'carcinoma in situ'), a complete sampling is necessary to rule out invasion. Designating in-situ or minimally invasive carcinomas limited to muscularis or above as early gallbladder carcinoma (EGBC) helps to alleviate the major geographical differences (West/East) in the criteria for 'invasiveness' to assign a case to pTis or pT1. Total sampling is crucial in proper diagnosis of such cases. A subset of invasive GBCs (5-10%) arise from the intracholecystic neoplasm (ICN, 'adenoma-carcinoma sequence') category. Approximately two-thirds of ICNs have invasive carcinoma. However, this propensity differs by subtype. True 'pyloric gland adenomas' (> 1 cm) are uncommon and scarcely associated with invasive carcinoma. A distinct subtype of ICN composed of tubular, non-mucinous MUC6⁺ glands [intracholecystic tubular non-mucinous neoplasm (ICTN)] forms a localised pedunculated polyp. Although it is morphologically complex and high-grade, it appears to be invasion-resistant. Some of the invasive carcinoma types in the gallbladder have been better characterised recently with adenosquamous, neuroendocrine, poorly cohesive and mucinous carcinomas often being more advanced and aggressive.