A 2-year-old-baby presented as a transfer from an outside hospital (OSH) due to concerns for possible acute cholecystitis. The patient has a history of abdominal pain for the last 2 weeks. The laboratory tests from the OSH were notable for leukocytosis. An abdominal CT scan showed a thickened gallbladder wall with numerous polypoid, non-mobile lesions. Eventually, the patient underwent laparoscopic cholecystectomy.
On gross examination, the gallbladder measured 8.8 x 1.5 x 1.2 cm, with multiple, scattered polypoid mucosal lesions mainly in the body and fundus. The largest lesion measured 2 cm in the greatest dimension (arrows) (Figure 1). No cholelithiasis was present.
Microscopic pictures of the gallbladder lesions are shown in Figures 2-4. As shown in Figure 2, The lesions had an intraluminal exophytic (mass-forming) growth pattern and papillary architecture (black arrows). Adjacent mucosa (white arrows) is also involved by papillary overgrowth of epithelium. Figure 3 showed that the neoplastic epithelial lining is composed of a combination of biliary (black arrow), gastric foveolar-type (white arrow), and intestinal-type epithelium with goblet cells (blue arrow). No high grade cytologic atypia or architectural abnormalities were identified. A higher-power image is shown in Figure 4 and highlights a collection of the lamina propria macrophages (black arrows).
Please select your diagnosis in the poll, then see the answer and the discussion in the links below.
Answer: Intracholecystic papillary neoplasm
Intracholecystic papillary neoplasm
Educational Objectives and Discussion:
- To understand the definition of intracholecystic papillary neoplasm
(ICPN) of the gallbladder by 2019 WHO Digestive System Tumours.
- To recognize the gallbladder lesions associated with metachromatic
leukodystrophy (MLD), an unusual neurologic disease in pediatric patients.
- To discuss the differential diagnosis of ICPN.
Intracholecystic papillary neoplasm (ICPN) is a precancerous lesion of the gallbladder. Per the 2019 WHO Digestive System Tumours , ICPN encompasses/replaces the previous terminologies, including biliary
adenoma, tubulopapillary adenoma, intracystic papillary neoplasm, and papillomatosis. Grossly, these tumors form distinct polypoid/exophytic intraluminal masses that are grossly visible. Microscopically, these tumors show papillary and/or tubular configuration with varying degrees of epithelial dysplasia. There are four morphologic patterns recognized: biliary, intestinal, gastric, oncocytic, or combination of these. These morphologic patterns contrast with classifications of intraductal papillary mucinous neoplasms (IPMN) of the pancreas in which oncocytic lesions (intraductal oncocytic papillary neoplasms (IOPN)) have been separated from IPMN due to distinct molecular findings. Mucosa surrounding ICPN may demonstrate dysplasia as well. About 50% of ICPNs are associated with invasive adenocarcinoma, but they have a better clinical outcome than conventional gallbladder adenocarcinomas [1, 2].
Our case exhibited low-grade ICPN with combined biliary, gastric, and intestinal differentiation. Adjacent mucosa also showed diffuse low-grade dysplasia. No high-grade dysplasia or invasive carcinoma was identified in extensively submitted sections. The aforementioned unusual findings in the gallbladder from a 2-year-old baby triggered further work-up since there is a well-known association between ICPN (previously called gallbladder papillomatosis) and metachromatic leukodystrophy (MLD) [3-5]. Genetic analysis was performed and the results revealed homozygous deletion of pathogenic variant c.1283C>T (p.Pro428Leu) in ARSA gene, which is associated with MLD. Brain MRI findings were non-specific and she has no history of developmental delay, neurologic symptoms, or regression.
MLD is a lysosomal storage disease caused by a deficiency of arylsulfatase A (ASA) with autosomal recessive inheritance in most cases. The ASA deficiency leads to the accumulation of sulfatides in the central and peripheral nervous system, which results in the destruction of the myelin sheath and eventually leads to neurologic symptoms such as seizures, loss of motor functions, and peripheral neuropathy . Sufatide accumulation is also detected in other organs, e.g., the gallbladder, kidney, lymph nodes, liver, and bone marrow. The gallbladder epithelial cells and macrophages contain cytoplasmic inclusions on electron microscopic examination, consistent with sulfatide accumulation [3, 7]. Almost all case reports described the presence of collections of the lamina propria macrophages in the gallbladder [3, 4, 7, 8], as seen in our case (Figure 4). This accumulation of macrophages could show histologic overlap with cholesterolosis, a more common finding in the gallbladder. In MLD, Giemsa and toluidine blue stains will show metachromasia of the cytoplasm of macrophages, consistent with the accumulation of sulfatide deposits. In contrast, the accumulation of cholesterol esters and triglycerides can be highlighted on frozen tissue with Oil red O or Sudan black stains.
According to the age of disease onset, there are three clinical subtypes of MLD, including late infantile-onset, juvenile-onset, and adult-onset. Our patient showed no neurologic symptoms but was homozygous for mutation of the ARSA gene, which encodes ASA. Numerous mutations in the ARSA gene have been identified, and c.1283C_T mutation in our case is usually seen in juvenile or adult-onset phenotype . That may explain the neurologic symptom-free status of our patient. A possible treatment for MLD so far is hematopoietic stem cell transplantation for selected cases . MLD-associated gallbladder abnormalities occasionally appear before the onset of neurologic symptoms or an MLD diagnosis . One case series with 34 patients reported that 76% of MLD patients showed gallbladder involvement . The gallbladder abnormalities consist of benign and malignant conditions, e.g., cholecystitis, cholelithiasis, mucosal hyperplasia, polypoid lesions (now most lesions are under the category of ICPN), and adenocarcinoma [3-5]. In conclusion, gallbladder abnormalities, in particular polypoid lesions, are rare during childhood. This condition can be seen in cases with MLD, Peutz-Jeghers’ syndrome, and pancreaticobiliary malunion . Pathologists should pay close attention to unusual gallbladder abnormalities in pediatric and adolescent patients to consider the above-mentioned possibilities and associated risk of malignancy.
Pyloric gland adenoma is composed of lobules of small, tightly packed, bland-looking glands that are morphologically similar to pyloric or Brunner glands. The uninvolved gallbladder mucosa is mostly devoid of dysplasia or pyloric gland metaplasia. Of note, pyloric gland nodules <0.5 cm arising in a background of pyloric gland metaplasia should not be designated as pyloric gland adenoma .
Reactive epithelial hyperplasia, commonly due to secondary causes (e.g., cholelithiasis, chronic cholecystitis, inflammatory bowel disease, primary sclerosing cholangitis), shows focal or diffuse papillary-shaped and elongated mucosal folds lined by bland epithelial cells with or without metaplastic changes. The presence of significant inflammation and no discrete, grossly visible mass-forming lesion, may help distinguish reactive hyperplasia from ICPN [1,10].
Invasive adenocarcinoma is present in about 50% of the ICPN cases at the time of diagnosis . Gallbladder adenocarcinoma arising in ICPN is more commonly associated with papillary growth patterns, biliary epithelial lineage, and high-grade dysplasia. The invasive component is often a tubular adenocarcinoma, although other types, such as mucinous, adenosquamous, or neuroendocrine carcinoma, have also been reported. Extensive sampling is warranted because approximately 60% of ICPN with carcinoma showed ≤ 5mm of invasive focus, and the carcinoma may also occur away from the main ICPN lesion. Some patients with non-invasive ICPN can also die of new primary carcinoma in the biliary tract, typically long after the diagnosis of ICPN, possibly due to the field cancerization phenomenon. This observation supports long-term surveillance of these patients with ICPN even after resection [1, 2].
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Case contributed by:
Rong Li, MD, PhD. Children’s of Alabama Benjamin Russell Hospital For Children
Conflict of Interest: NO