Multiple Colonic Polyps Research Articles

Peutz-Jeghers syndrome: A case series

IntroductionPeutz-Jeghers syndrome (PJS) is a rare hereditary disorder characterized by gastrointestinal hamartomatous polyps, due to mutation of the STK11/LKB1 gene located on chromosome 19p. The polyps are most commonly found in the small bowel followed by colon. Case presentationOur case series includes 4 patients, three being male and one female. Each of them either presented with abdominal pain and other associated symptoms. Oral cavity and lip melanin pigmentation were common. CT abdomen revealed multiple large jejunal, ileal, gastric and colon polyps. Cancer was found in one patient. Different surgical approaches were adopted. All recovered well. DiscussionPJS is an autosomal dominant disorder with an estimated incidence of 1:50,000 to 1:200,000 cases with a significant family history. Mostly found in small bowel followed by colon, it can also occur in a rare organ like gall bladder as evident in our case. PJS carries a substantial risk for gastrointestinal cancer. The treatment modality depends on the site of polyp, mode of presentation and availability of the expertise. ConclusionPJS is a common disease in our part which is usually observed in teen age groups male. They have a varied presentation, from intestinal obstruction (due to intussusception) to GI bleeding. Colonic malignancy at young age may be the first presentation of the disease. Observation of melanin pigmentations on lips helps diagnose the disease; and one should always look at this findings in a young patient with pain abdomen or in intestinal obstruction to confirm/exclude the disease.

Gastrointestinal Polyps and Polyposis in Individuals Harboring Germline CHEK2 Mutations.

Checkpoint kinase 2 is a tumor suppressor gene in the deoxyribonucleic acid damage checkpoint system that may be mutated in several cancers. Patients with germline checkpoint kinase 2 mutations and multiple colon polyps were noted during routine care, and genetic testing is recommended for patients with as few as 10 lifetime polyps. This study assessed whether checkpoint kinase 2 is associated with attenuated or oligopolyposis and characterized the gastrointestinal clinicopathologic profile. Retrospective observational study. Records from patients harboring germline checkpoint kinase 2 mutations from 1999-2020 were reviewed. A total of 45 patients with germline checkpoint kinase 2 mutations with endoscopic examinations. Description of clinicopathologic variables. Twenty-five of 45 patients had polyps: 3 with only upper gastrointestinal polyps, 17 with only lower gastrointestinal polyps and 5 with both upper and lower gastrointestinal polyps. The most common germline checkpoint kinase 2 mutations in patients with polyps were p.S428F (n = 10), p.I157T (n = 4) and p.T476M (n = 2), with other mutations present in 1 patient each. Among patients with lower gastrointestinal polyps, 9 had adenomas, 6 had serrated polyps, 1 had an inflammatory polyp and 6 had both adenomatous and serrated polyps. Three patients (p.I157T, n = 2; p.R117G, n = 1) had >10 adenomas, and 1 (p.G259fs) had 18 serrated polyps. Five patients (11.1%) developed colorectal adenocarcinoma, including 2 with >10 adenomas. Five patients with p.S428F (50%) exclusively had right- sided adenomas. Single-center descriptive study. Germline checkpoint kinase 2 mutations should be considered in patients with polyposis. The preponderance of right- sided adenomas in patients with p.S428F mutations suggests the importance of right-sided colonoscopy in these patients. See Video Abstract.

HGG-01. DURABLE RESPONSE TO IMMUNOTHERAPY IN AN ADOLESCENT PATEINT WITH CONSTITUTIONAL MISMATCH REPAIR DEFICIENCY CMMRD AND SYNCHRONOUS THREE PRIMARY MALIGNANCIES

Abstract BACKGROUND Familial Cancer Syndrome FCS is of particular concern in Saudi Arabia due to the high rates of consanguinity. Constitutional mismatch repair deficiency Syndrome (CMMRD) is an autosomal recessive FCS with a wide spectrum of malignancies Caused by Biallelic germline mutations in one of 4 mismatch repair genes (MLH1, PMS2, MSH2, and MSH6). METHODS we report 13 yr. Saudi boy, previously healthy with multiple café-au-lait (CAL) macules, and Consanguineous parents with a positive family history of Malignancy. presented with progressive headache, vomiting, abdominal pain, weight loss, and microcytic anemia. MRI Brain showed a Large left hemispheric necrotic mass, MRI abdomen: Circumferential gastric body wall thickening Distal transverse colon intraluminal polypoid mass, and liver hypodense lesion. He had a Resection of the brain tumor and Upper GI endoscopy + colonoscopy with polypectomy: which showed an Ugly gastric ulcer, and multiple colonic polyps. RESULTS Brain tumor molecular pathology: Gliosarcoma WHO grade 4 with negative IHC expression in PMS2 protein, hypermutant tumor with somatic PMS2 ATRX, TP53, NFI, and PIK3R1 genes mutation. stomach biopsy confirmed invasive gastric adenocarcinoma and Colonic polyp biopsy: Tubulovillous adenoma. Genetic testing Detect pathogenic Biallelic germline PMS2 mutation. He received adjuvant focal Brain radiation therapy 59.4Gy/33 F concurrent with immunotherapy (PD-1) inhibitor Nivolumab. Follow-up Abdominal imaging showed excellent response to immunotherapy with no significant residual lesion. MRI of the brain showed surgical bed multi-cystic lesions with thick nodular enhancement suggestive either of radiation necrosis vs. progressions/pseudoprogression. repeated MRI confirmed further progression of the enhancing surgical cavity lesion which was unresectable. CTLA-4 Inhibitor ipilimumab was added to Nivolumab to optimize therapy. UpToDate our patient is clinically stable on Maintenance Nivolumab with no side effects. CONCLUSION Our case confirms immunotherapy’s efficacy for treating CMMRD-related cancers, which can improve survival while reducing toxicity from less effective conventional therapies.

SAT509 The Clinical Significance of Cribriform Morular Thyroid Carcinoma

Abstract Disclosure: G. Soh: None. K. Sek: None. S. Yang: None. M. Nga: None. S. Mok: None. We present two young (aged below 30) female patients who were diagnosed with the rare cribriform morular thyroid carcinoma. Both patients presented with neck swellings and underwent total thyroidectomy for the thyroid malignancies. The histological diagnosis prompted subsequent genetic evaluation. Both patients demonstrated genotypic and phenotypic evidence of familial adenomatosis polyposis (FAP) syndrome. One of the patients had a mutation which resulted in a premature translational stop signal in the adenomatous polyposis coli (APC) gene. She was eventually diagnosed with adenocarcinoma in 2 colonic polyps and underwent a curative pan-proctocolectomy. The other patient was diagnosed clinically with FAP as she had multiple (30-40) colonic polyps which were tubular adenomas. She had a variant of unknown significance in the APC gene. She declined surgery and remained on colonoscopic surveillance. Both patients’ thyroid cancers are in clinical remission. While uncommon, diagnosing cribriform-morular thyroid carcinoma is significant as 25 to 30% of patients harbour genetic mutations in the APC gene on chromosome 5q21. This is associated with FAP syndrome, an autosomal dominant genetic syndrome characterized by young-onset colonic polyposis, usually of malignant potential. Additionally, these patients may exhibit features of Gardner’s syndrome, a subset of FAP syndrome in which patients can develop extra-colonic manifestations such as osteomas of the mandible and supernumerary teeth. Histologically, cribriform morular thyroid carcinoma are well circumscribed and show a variable combination of follicular, cribriform, papillary, trabecular, solid and morular patterns. There is nuclear and cytoplasmic staining for beta catenin, as the inactivating APC mutation causes a loss of beta catenin destruction complex, impeding beta catenin degradation and increasing its nuclear translocation. This is a key event in thyroid tumorigenesis. The diagnosis of cribriform morular thyroid carcinoma should alert the clinician about the possibility of FAP with consideration for further clinical and genetic evaluation to confirm the diagnosis. References1)Cameselle-Teijeiro, J. M., Peteiro-González, D., Caneiro-Gómez, J., Sánchez-Ares, M., Abdulkader, I., Eloy, C., Melo, M., Amendoeira, I., Soares, P., & Sobrinho-Simões, M. (2018). Cribriform-morular variant of thyroid carcinoma: A neoplasm with distinctive phenotype associated with the activation of the Wnt/β-catenin pathway. Modern Pathology, 31(8), 1168–1179. https://doi.org/10.1038/s41379-018-0070-2 2)Peiling Yang, S., & Ngeow, J. (2016). Familial non-medullary thyroid cancer: Unraveling the Genetic Maze. Endocrine-Related Cancer, 23(12). https://doi.org/10.1530/erc-16-0067 Presentation Date: Saturday, June 17, 2023

Adherence to Mediterranean diet and its association with multiple colonic polyps of unknown origin: a case-control study.

Multiple colonic polyps do not have a genetic origin in most patients, and the cause of this phenotype remains elusive. Environmental factors, such as diet, could be related to this phenotype. Our aim was to investigate the relationship between the adherence to Mediterranean diet and multiple colonic polyps of unknown origin. A case-control pilot study was carried out with a sample of 38 individuals, including 23 cases with more than 10 adenomatous or serrated polyps from the national multicenter project EPIPOLIP and 15 healthy controls with normal colonoscopy. A validated Spanish version of the MEDAS questionnaire was administered to cases and controls. Adherence to Mediterranean diet was higher in controls than in patients with multiple colonic polyps (MEDAS score: 8.6 ± 1.4 vs. 7.0 ± 1.6; p = 0.01). Optimal overall adherence to the Mediterranean diet pattern was significantly higher among the controls than among cases (MEDAS score >9: 46% vs. 13%; OR 0.17; 95% CI 0.03-0.83). Non-optimal adherence to the Mediterranean diet acts as a risk factor for developing colorectal cancer derived from colorectal polyps. Our results suggest that environmental factors play a role in the pathogenesis of this phenotype.

Abstract #1412835: A Case of Cowden Syndrome

Cowden syndrome is part of the PTEN Hamartoma Tumor Syndrome spectrum. It is characterized by the presence of multiple hamartomas on the skin and mucous membranes and an increased risk of developing cancers of the thyroid, breast, uterus, kidney, colon, rectum and skin. Most cases are caused by genetic changes in the phosphatase and tensin homolog (PTEN) gene, inherited in an autosomal dominant manner. It is rare with an estimated prevalence of 1 in 200,000 to 250,000. A 36-year-old female presented to the Veteran Affairs Endocrinology clinic for follow up of thyroid cancer. She had undergone a total thyroidectomy 9 years prior due to a large goiter, with pathology revealing papillary thyroid cancer. She received radioactive iodine ablation afterwards. Thyroid ultrasound showed a heterogenous soft tissue density measuring 1.8 x 1.1 x 1.6 cm in the left thyroid bed. Fine needle biopsy of the mass confirmed recurrent papillary thyroid cancer. Her medical history includes endometriosis with right ovary cyst for which she underwent total hysterectomy with bilateral salpingo-oophorectomy, benign colon polyps status post resection, gallbladder polyps status post cholecystectomy, bilateral breast masses (measuring 0.5 cm on the right and 0.8 cm on the left) and multiple skin lesions. Family history is significant for multiple benign skin lesions and colon polyps in her father and breast cancer and endometriosis in her paternal aunts. Due to her extensive personal and family history of tumors, a comprehensive hereditary cancer panel was sent out. Results came back positive for the PTEN gene, indicating a diagnosis of Cowden syndrome. She was referred to oncology for cancer surveillance, dermatology for regular skin checks and surgery for prophylactic mastectomy. She does not plan to have children, and she was advised to notify her first-degree family to have genetic testing done. Patients with Cowden syndrome may present to the Endocrinology clinic for management of non-medullary thyroid cancer, multinodular goiter or Hashimoto’s thyroiditis and may be noted to have multiple skin and mucous membrane lesions. They may report a history of breast tumors, endometrial abnormalities and polyps as in this case. After diagnosis is confirmed by genetic testing, cancer surveillance is the major focus of medical management given the high risk of malignancy.

ODP488 Incidental papillary thyroid cancer found after hemi-thyroidectomy in man with MUTYH-associated polyposis

Abstract MUTYH-associated polyposis (MAP) is an autosomal recessive syndrome caused by a mutation to the MUTYH gene, a base excision repair gene that repairs oxidative damage to DNA. Mutations to both allelic copies of this gene typically manifest as multiple colonic polyps, which develop by middle age. Individuals with MAP are also at higher risk for developing non-gastrointestinal (GI) cancers including those affecting the ovary, bladder, breast, endometrium, and possibly thyroid. A 66-year-old man with a history of MAP complicated by colonic polyposis requiring subtotal colectomy, an esophageal adenocarcinoma resected by esophagectomy, and a gastrointestinal stromal tumor also resected was referred to endocrinology clinic for an incidental thyroid nodule found on routine surveillance. The patient denied prior neck radiation but reported having a daughter and cousin with thyroid cancer. Ultrasound showed a left 3.3 by 2.8 by 1.6 cm thyroid nodule with multiple lobulations. Although a fine needle aspiration (FNA) of the nodule was benign, a repeat ultrasound several months later noted an increase in size to 3.5 by 3.5 by 2. 0 cm. Given the nodule's significant growth, the patient's history of MAP, and family history of thyroid cancer, the patient underwent a left hemi-thyroidectomy. Pathology revealed that the nodule was a follicular adenoma, however also identified two papillary microcarcinomas, measuring 1 and 2 mm. The patient was started on levothyroxine 50 mcg with a goal TSH below 0.5 mU/L and was monitored with ultrasounds which were unremarkable. In 2021, the national cancer institute estimated approximately 150,000 cases of colorectal cancer (CRC) with a 65% 5-year survival, compared to 44,000 cases of thyroid cancer with a 98% 5-year survival. Although the incidence of CRC in patients with MAP is high, approximately 43-63% by age 60, the risks of several associated non-GI malignancies are not as well defined. The national comprehensive cancer network (NCCN) and the American College of Gastroenterology (ACG) both published guidelines regarding appropriate screening for both GI and associated non-GI malignancies. In regards to thyroid cancer, both advise screening in patients with familiar adenomatous polyposis (FAP), another familial condition, due to the increased risk of papillary thyroid cancer (PTC) of approximately 1-2%. The evidence concerning MUTYH is not as strong, with the ACG recommending annual thyroid cancer screening, although the quality of evidence is low. Since a thyroid ultrasound is both low-cost and non-invasive and the overall survival of patients with PTC is high, we agree that patients with MAP be screened with thyroid ultrasounds. This case highlights the possibility that thyroid cancer is a manifestation of MAP, and a lower threshold to send for surgery may be warranted for those with other risk factors such as a family history or prior neck radiation. Presentation: No date and time listed

PMON104 Sellar Gangliocytoma-Pituitary Neuroendocrine Tumor (PitNET) Presenting As Acromegaly

Abstract Growth hormone (GH)-secreting pituitary neuroendocrine tumors (PitNET) arising from somatotrophs is the most common cause of acromegaly. It may rarely develop in the setting of a growth hormone-secreting PitNET associated with a neuronal tumor composed of neoplastic ganglion cells, the so-called mixed gangliocytoma somatotroph PitNET. We present a case of acromegaly which proved to be due to a mixed gangliocytoma somatotroph PitNET on pathology.A 58-year-old, healthy woman presented to the ER with a 3-day history of left-sided vision loss and worsening headache. MRI revealed 4.5×4.2×3.8 cm heterogeneously enhancing bilobed mass consistent with a pituitary PitNET with suprasellar extension causing compression of the optic chiasm, invasion into the left cavernous sinus and partial encasement of the left internal carotid artery. She had coarse facial features, wide feet, multiple skin tags, and a history of multiple colonic polyps. Biochemical work up revealed an IGF-I of 664 ng/ml (50-317), AM cortisol 19.7 mg/dl, ACTH 30 pg/ml, prolactin 15.5 ng/ml, FSH 35.6 mIU/ml, LH 11.3 mIU/ml, and FT4 0.7 ng/dl (0.70-1.48). She underwent endoscopic transsphenoidal resection of the tumor. Histopathology demonstrated mature ganglion cells with neuropil-like areas, intermixed with small cell components. The neuronal population was immunopositive for NeuN (Neuronal nuclei antibody), synaptophysin, and NF (Neurofilament). PitNET cells were positive for GH, prolactin, Pit- 1 transcription factor and the somatostatin 5 receptor, histological features consistent with mixed gangliocytoma and sparsely granulated somatotroph pitNET. Some ganglion cells also showed weak immunostaining with Pit-1. A 3-month follow-up MRI showed a residual 3 cm lesion. IGF-I improved but was still elevated at 456 ng/ml associated with a GH 2.9 ng/ml. Medical treatment with pasireotide was recommended, but the patient temporarily declined further treatment to explore other options with her Naturopath.Gangliocytomas are a rare, benign, slow-growing, differentiated form of neuroblastic tumors of sympathetic nerve fibers, largely extracranial and rarely present in the sellar region, most frequently in association with a PitNET, forming the so-called mixed gangliocytoma PitNET. Definitive diagnosis is established by histological and immunohistochemical studies. Though PitNET components of mixed gangliocytoma PitNET are known to frequently secrete an excess hormone, the ganglionic components also show immunoreactivity for hypothalamic releasing hormones along with other neuroendocrine markers. The histological origin of these mixed tumors is controversial, but the small population of ganglionic cells that express the acidophilic lineage transcription factor, Pit-1, favors the theory of transdedifferentiation of neuroendocrine cells into neuronal elements. Treatment of mixed gangliocytoma- PitNET is similar to other PitNETs and the presence of neural components does not modify aggressiveness or risk of recurrence after surgical resection, as gangliocytomas have a low proliferative index. Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.

Germline mutations in WNK2 could be associated with serrated polyposis syndrome

BackgroundPatients with serrated polyposis syndrome (SPS) have multiple and/or large serrated colonic polyps and higher risk for colorectal cancer. SPS inherited genetic basis is mostly unknown. We aimed to identify...

S2040 Hiding in Plain Sight: The Challenge of Diagnosing Medullary Carcinoma of the Colon

Introduction: Medullary carcinoma of the colon (MCC) represents < 3% of colon cancers and is characterized by microsatellite instability (MSI) leading to poor cellular differentiation. With its relative rarity and ambiguous histology, MCC remains a challenging, frequently-missed diagnosis. Case Description/Methods: A 56-year-old post-menopausal female with asymptomatic iron-deficiency anemia was referred to gastroenterology for bidirectional endoscopy. Colonoscopy identified multiple colonic polyps and a mass nearly obstructing the ascending colon. Abdominopelvic CT showed an 8.1 cm mass with associated mesenteric lymph nodes but no extracolonic involvement. CEA levels were normal. Initial biopsy demonstrated poor tumor differentiation. Immunohistochemical staining was positive for CD45, a marker of lymphocytic infiltration, but negative for cytokeratin (CK) 20, caudal-related homeobox gene 2 (CDX-2), and synaptophysin, interpreted as an undifferentiated carcinoma. The patient was referred to colorectal surgery and underwent laparoscopic right hemicolectomy without complication. Biopsy of the resected tumor redemonstrated the initial biopsy results without lymph node involvement. Additional stains showed high MSI and negativity for extracolonic tumor markers. These findings confirmed the tumor as a non-adenocarcinoma primary colonic lesion suggestive of MCC. Discussion: The differential diagnosis for poorly-differentiated colonic tumors includes poorly-differentiated adenocarcinoma (PDA), neuroendocrine tumor (NET), MCC, and metastasis. This ambiguity has led to tumor misidentification in up to 66% of MCC cases; however, several key features can distinguish among these carcinomas. MCC displays negative chromogranin and synaptophysin staining, unlike NET. MCC almost invariably has high MSI and is infrequently CK20 and CDX-2 positive, unlike PDA. Clinically, MCC is more likely to present in the eighth decade, in females, and in the right colon than NET or PDA. MCC frequently follows an indolent course with good prognosis, while PDA often grows and spreads aggressively. While this case had a uniquely young age of presentation, it otherwise exhibits known clinical and histological features of MCC. As familiarity with these features rises and the use of MSI testing expands, accurate diagnosis of MCC will likely improve. With the expansion of colon cancer screening, the incidence of MCC is likely to rise, highlighting the importance of timely, accurate diagnosis when facing poorly-differentiated colonic tumors.

Clinical Characteristics and Associated Factors of Colonic Polyps in Acromegaly.

To investigate the clinical characteristics and associated factors of colonic polyps in patients with acromegaly. Clinical characteristics and colonoscopy findings of 86 acromegaly patients who received treatment were retrospectively reviewed, and colonoscopy findings and the correlation with growth hormone (GH)-secreting pituitary adenoma (GHPA) volume and hormonal/metabolic levels were analyzed. The prevalence of colonic polyps in acromegaly patients was 40.7% and increased significantly with advanced age, especially in those ≥50 years. Multiple polyps (62.8%) and colonic polyps in the left colon (54.2%) were detected more frequently. Compared to acromegaly patients without polyps, those with polyps displayed higher insulin-like growth factor-1 × upper limit of normal (IGF-1×ULN) levels (P=0.03). IGF-1 levels and GHPA volumes in patients with polyps showed increasing trends, although the differences were not significant. GH levels were higher in patients with polyps of diameter ≤5 mm than those with polyps of diameter >5 mm (P=0.031). The univariate and multivariate logistic regression analysis revealed that GHPA volumes (OR: 1.09, 95% CI: 1.01-1.20; P=0.039) and IGF-1×ULN Q2 levels (OR: 6.51, 95% CI: 1.20-44.60; P=0.038) were independent factors for predicting the risk of colonic polyp occurrence in acromegaly patients. A nomogram was prepared to evaluate the risk of colonic polyps in acromegaly patients. The acromegalic patients are a population with a high prevalence of colonic polyps. GHPA volumes and IGF-1×ULN levels may be predictors of colonic polyp occurrence.

Множественные остеомы околоносовых пазух

Osteoma of the paranasal sinuses is a benign, slowly growing, most often solitary, formation. Detection of multiple osteomas of the paranasal sinuses is casuistic in nature. According to the literature, their occurrence is 0.13% in computed tomography of the paranasal sinuses. Clinically osteoma is asymptomatic. Multiple osteomas of the paranasal sinuses may be a manifestation of Gardner’s syndrome, which was first described in 1953 as a triad of symptoms: multiple colon polyps, multiple osteomas, and skin and subcutaneous soft tissue tumors. In addition, patients are also diagnosed with dental and skeletal anomalies, retinal pathology. Gardner’s syndrome is hereditary autosomal dominant. The article presents a clinical case of a patient with multiple osteomas of the paranasal sinuses. The practical interest of this observation is its rare occurrence and the need to discuss options for choosing a therapeutic, including surgical, tactic and further management (dynamic monitoring, additional examination) of the patient. The case of multiple osteomas seems to be a rare pathology, possibly hereditary. Despite the benign nature of osteomas of the paranasal sinuses, the patient should be informed about the need for further observation, should be included in the dynamic observation group, and additionally examined by related specialists (dermatologist, dentist, gastroenterologist, ophthalmologist).

Successful colonoscopic decompression of colocolic intussusception with polypectomy in a five-year-old

The incidence of colocolic intussusception is rare in the pediatric population. When it is encountered, there should be a high index of suspicion for colonic neoplasm acting as the lead point. Our case involves a 5-year-old male who presented with left-sided colocolic intussusception secondary to multiple colonic polyps. He underwent colonoscopy with successful reduction of the intussusception in addition to endoscopic removal of multiple colonic polyps. The use of endoscopy to resolve the intussusception proved to be a valuable tool for our patient as it avoided subjecting the patient to an operation and allowed for surveillance of the remainder of the colon. IV. • Colocolic intussusception is rare in children. • Management frequently includes air enema, but open or laparoscopic surgical resection has also often been reported. • We introduce the use of colonoscopy for reduction of colocolonic intussusception, which has not previously been described.

Prophylactic subtotal colectomy in a patient with an AXIN2 mutation.

A number of genetic syndromes that predispose patients to colon cancer have been well described, allowing for improved surveillance, diagnosis and treatment. However, other syndromes likely exist but have yet to be thoroughly characterized. I report the case of a 50-year-old woman who was found to have over 50 polyps on routine screening colonoscopy. Genetic sequencing revealed a mutation in Axin2, a rare gene implicated in oligodontia-colorectal cancer syndrome. It was later found that the patient lacks several permanent teeth, as does her mother, who also had a history of multiple colonic polyps. Given the rarity of Axin2 mutations, there are no guidelines for management of such patients. This highlights the importance of a thorough review of system when screening for colon cancer as well as documenting cases of Axin2 mutations to create management guidelines for these patients.

Classification of the canonical splice alteration MUTYH c.934-2A > G is likely benign based on RNA and clinical data.

MUTYH-associated polyposis (MAP) is an autosomal recessive disorder characterized by the development of multiple adenomatous colonic polyps and an increased lifetime risk of colorectal cancer. Germline biallelic pathogenic variants in MUTYH are responsible for MAP. The MUTYH c.934-2A > G (NM_001128425.1) variant, which is also known as c.850-2A > G for NM_001048174.2, has been identified in our laboratory in more than 800 patients, including homozygous and compound heterozygote carriers. The variant was initially classified as a variant of uncertain significance (VUS) because of lack of a MAP phenotype in biallelic carriers. In two unrelated female patients who were heterozygous carriers of this variant, further testing by RNA sequencing identified an aberrant transcript with a deletion of 9 nt at the start of exon 11 (MUTYH r.934_942del9). This event is predicted to lead to an in-frame loss of three amino acids in a noncritical domain of the protein. This was the only splice defect identified in these patients that was not present in the controls, and the aberrant transcript is derived exclusively from the variant allele, strongly supporting the cause of this splice defect as being the intronic variant, MUTYH c.934-2A > G. The splicing analysis demonstrating a small in-frame skipping of three amino acids in a noncritical domain, along with the absence of a MAP phenotype in our internal cohort of biallelic carriers, provides evidence that the variant is likely benign and not of clinical significance.

Gardner-associated fibroma presenting as an unusual floor of mouth mass in a child

Floor of mouth lesions in the paediatric population are uncommon. The spectrum of pathology that afflicts the floor of mouth spans inflammatory conditions, developmental anomalies, vascular malformations and benign tumours or malignancies. We report a rare case of Gardner-associated fibroma (GAF) presenting as a slow-growing floor of mouth mass in a 10-year-old boy. GAF is associated with Gardner’s syndrome (GS) and familial adenomatous polyposis (FAP), both of which are associated with multiple colonic polyps and increased risk of colorectal malignancy. To our knowledge, this case report represents the first case in the literature of a GAF presenting in the floor of mouth of a paediatric patient, and discusses the clinical implications of this rare diagnosis.

S1777 Polyps and an Uninvited Host

Introduction: Blood fluke illness like Schistosomiasis is considered rare in the United States. Most cases are reported in patients that have migrated from endemic zones like Africa or Asia. Occasionally this infection is seen in individuals from non-endemic regions whereby travel history plays an important role in diagnosis. Zoonotic diseases can be life threatening, thus prompt treatment is crucial to avoid major complications. Herein, we present an European individual living in the United States who underwent routine colon cancer screening in which the polyps that were biopsied revealed calcified Schistosoma eggs. Case Description/Methods: A 67-years-old male with past medical history of hypertension, goiter, and hyperlipidemia presented to the outpatient gastroenterology clinic for routine screening. Coloscopy done showed multiple colonic polyps, the largest being 1 cm in diameter. Pathology reported tubular adenomatous polyps with calcified Schistosoma eggs. Patient was asymptomatic and the physical exam was benign. On social and travel history, he pointed out that he lived in Angola from 1971-1973. Treatment with Praziquantel 600 mg three times daily was started, and the patient was asked to be followed up in 3 months. Negative serology was reported after treatment. Colonoscopy done 3 years later showed complete resolution of the polyps. Discussion: Schistosoma is a blood fluke causing Bilharziasis, an infection caused by freshwater parasitic worms. The parasite itself can be found living in certain freshwater snails. About 5 Schistosoma species have been identified to infect the human body with S. Mansoni and S. Japinicum being the main culprit for intestinal disease. Schistosomiasis is more prevalent in Sub-Saharan Africa with approximately 200 million cases reported worldwide. Infection occurs once the cercariae released by the snail penetrates the skin and begins its life cycle. Most individuals are asymptomatic. Migrating eggs cause bowel inflammation by triggering granulomatous reactions resulting in ulcerations, blood loss, and scaring. The same is true for Host immune response. The most common symptoms for intestinal Schistosomiasis are chronic intermittent abdominal pain, poor appetite, and diarrhea. Chronic ulcerations can be seen in severe cases with strictures as late complications. A combination of Polypectomy plus Praziquantel is often use as treatment. Follow up Colonoscopy to assure resolution is recommended.Figure 1.: Endoscopic mucosal removal of a Cecal granular cell tumor.

A Most Unusual Polyposis

Question: A 19-year-old woman with a history of lactose intolerance, nephrolithiasis, gastroesophageal reflux, irritable bowel syndrome, and multiple colonic polyps presented with intermittent diffuse abdominal pain associated with passage of loose stool over the past several years. Her only medications included a vitamin D supplement and omeprazole. She had a family history of colorectal cancer in her paternal great grandfather and paternal great uncle.

APC germline variant analysis in the adenomatous polyposis phenotype in Japanese patients.

Familial adenomatous polyposis (FAP), an autosomal dominant disorder characterized by multiple colonic polyps, is caused by a germline pathogenic variant of the APC gene. However, this variant is not detected in up to 30% of patients with the adenomatous polyposis phenotype. We performed next-generation sequencing (NGS) to identify the causative genes in FAP patients with 10 or more polyps. For patients in whom the APC germline variant was not able to be identified, we screened for APC mosaicism using high-coverage NGS of APC with DNA from leucocytes and/or frozen tissue. The pathogenic APC germline variant was found in 93.3%, 71.6%, and 17.1% of patients with profuse-type polyposis, sparse-type polyposis, and oligo-polyposis, respectively. The APC germline variant detection rate in patients with FAP-related diseases was 69.7% for fundic gland polyposis, 79.7% for duodenal adenoma, 94.7% for desmoid tumor, and 71.4% for thyroid cancer, with increasing numbers of extracolonic lesions associated with an increasing APC germline variant detection rate. A mosaic test detected nine patients with APC mosaicism. A comparison of APC-associated polyposis with APC mosaicism showed that patients with APC mosaicism had a low frequency of duodenal adenoma and a family history of colonic polyposis. We determined the detection rate of the APC germline variant by phenotype and identified APC mosaicism. Genetic testing of FAP patients is important because it can help with surgical decision-making, monitoring, and genetic counseling. Furthermore, genetic testing by NGS proved to be an effective method of detecting APC germline variants.

Endoscopic Treatment and Literature Review of Delayed Perforation After Colorectal Polypectomy: A Case Report

In this report, one patient developed abdominal pain in 24 hours after resection of multiple colonic polyps, and relieved after the application of symptomatic treatment. However, the patient had abdominal pain with fever and abdominal muscular tension within 40 hours. Perforation was considered in the patient based on the results of abdominal CT. Following painless colonoscopy, the patient was provided with endoscopic closure of the perforation successfully. Postoperatively, the patient was supplied with fasting of oral feeding and drinking water, anti-infectious therapy and other symptomatic therapies. The patient was discharged from the hospital successfully without the performance of surgery.