Mucosal Schwann cell “hamartoma”: clinicopathologic study of 26 neural colorectal polyps distinct from neurofibromas and mucosal neuromas. Am J Surg Pathol. 2009;33:781-787. [PMID: 19065103 DOI: 10.1097/pas.0b013e31818dd6ca]

Gastrointestinal Tactile Corpuscle-Like Bodies: Report of Two Cases and Review of the Literature

Gastrointestinal tactile corpuscle-like bodies are a rare, incidental, entirely benign finding. It is mainly reported in the colorectum and esophagus/gastro-esophageal junction. Rare cases have been documented in the stomach. Here, we present two cases of gastric and colonic tactile corpuscle-like bodies of a 38-year-old female and a 55-year-old male, respectively. Endoscopically, the colonic lesion was resected as an adenomatous polyp, while the gastric biopsies were taken to rule out Helicobacter pylori (H. pylori) gastritis. Microscopically, both specimens revealed the same histopathologic aspects of eosinophilic fibrillary material with round to oval cells and peripherally placed nuclei. Immunohistochemically, these lesions were positive for anti-S100, confirming the diagnosis of tactile corpuscle-like bodies. A thorough literature review is provided.

Schwann Cell Hamartoma Presenting as a Colonic Polyp: A Rare Case Report With a Literature Review

Mucosal Schwann cell hamartomas (MSCHs) are non-common noncancerous growths derived from Schwann cells in the peripheral nervous system, often found unexpectedly during routine colonoscopy examinations. These growths primarily occur in the colon, although they can also appear in the esophagus and are not linked to familial cancer syndromes. Diagnosis relies on specific histological characteristics and staining patterns. It is essential to distinguish MSCHs accurately since their appearance can closely resemble that of malignant tumors. Characteristically, these hamartomas test positive for S-100 protein but do not exhibit markers typical of other gastrointestinal growths, such as gastrointestinal stromal tumors (negative for KIT), leiomyomas (negative for smooth muscle actin), neurofibromas (negative for CD34), and perineuromas (negative for epithelial membrane antigen or claudin-1). This report discusses the case of a 48-year-old woman who was diagnosed with MSCH during a screening colonoscopy.

An Unusual Case of Schwann Cell Hamartoma in Colon

Schwann cell tumors are benign tumors originating from Schwann cells of the peripheral nervous system and are extremely rare in the gastrointestinal system. They usually originate in the colon or rectum but can also occur in the esophagus and small intestine. Their occurrence is rare in GI tract and mainly in the sigmoid colon. Schwann cell tumors have no association with any familial cancer syndromes. We present a 65-year-old female patient who underwent routine colon cancer screening. In addition to open mouth diverticulosis, she was found to have a 3 mm polyp, which was diagnosed as a Schwann cell hamartoma after a biopsy. This study aimed to present this rarely reported case in the literature as an example of a tumor that should be included in the differential diagnosis when considering submucosal colonic lesions. Though the reported reoccurrence rate is low, this case highlights the lack of published guidelines regarding appropriate follow-up surveillance periods.

A Rare Case of Schwann Cell Hamartoma in the Duodenum

Mucosal Schwann cell hamartomas (MSCHs) are benign neural lesions that are not associated with inherited syndromes and are primarily found in the distal colon. We report the first case of an MSCH in the duodenum. This case highlights the expansive nature of MSCHs and discusses the implications of this finding in the duodenum and in the context of a hematologic malignancy.

Nonpolypous Hamartomas of the Gastrointestinal Tract: An Updated Review on Classification, Denominations, and Clinical Management

Purpose

To perform the first systematic report about histological subtypes of nonpolypous hamartomas of the gastrointestinal (GI) tract, from esophagus to anal canal.

Design

From over 19,000 studies about hamartomas, most of them published as case series or case presentations, we have selected the most representative ones for the GI tract, excluding polyposis syndromes. To have a whole picture of these hamartomas, all of the data were combined with the personal experience of the authors who are GI pathologists.

Results

The examined articles showed predominance of vascular and combined vascular and mesenchymal hamartomas. Arteriovenous hamartomas or Brunner gland hamartomas are mainly diagnosed in the small intestine, with preponderance for duodenum. Other malformations such cavernous hamartomas are more specific for the colorectal segments, whereas chondromatous hamartomas or those derived from the neural ectoderm were mostly reported in the esophagus. As newly recognized entities were admitted in the last years, misdiagnosis is frequent, and the best therapeutic approach is far to be known.

Conclusion

Even rare, hamartomas of the GI tract need to be differentiated from tumors and familial polyposis syndromes. Knowing their proper denominations and possible complications is valuable for gastroenterologists, pathologists, and surgeons, to be aware in the differential diagnosis.

[Mesenchymal tumors and tumor-like lesions of the gastrointestinal tract: an overview]

Mesenchymal tumors and tumor-like lesions of the gastrointestinal (GI) tract are uncommon. They vary from reactive tumefactive lesions and benign neoplasms to highly aggressive sarcomas. Among them, GI stromal tumors (GISTs) are most common, followed, with less frequency, by smooth muscle and neurogenic tumors. The major challenge resides in correctly identifying GISTs and providing a comprehensive report (including risk assessment and genotyping) that represents the basis for an optimized surgical-oncological treatment and/or adjuvant therapy. On the other hand, the challenge of benign lesions is to find a good name (well understandable and reproducible diagnostic term) that helps avoid diagnostic ambiguity and prognostic uncertainty so that overprognostication and overtreatment can be prevented. Moreover, several recently described genetically defined benign and malignant entities need be correctly diagnosed due to their special "targeted" therapeutic options and to further characterize their clinicopathological and biological properties in the future. These recent entities include aggressive epithelioid inflammatory myofibroblastic sarcoma (ALK-RANBP2-driven), malignant gastrointestinal neuroectodermal tumor (EWSR1-ATF1/CREB-related), NTRK-rearranged neoplasms, and, most recently, colorectal NUTM1-rearranged sarcomas. This review highlights the major clinicopathological features of gastrointestinal mesenchymal lesions in light of recent developments.

Mucosal Schwann cell hamartoma of the gallbladder

Mucosal Schwann cell hamartoma (MSCH) is a rare benign neurogenic tumor characterized by pure S100p positive spindle cell proliferation. Most cases occur in the distal colon. Involvement of the gall bladder is exceedingly rare. There have been no reports of recurrence or a syndromic association with MSCH. Herein, we describe a case of MSCH of the gallbladder in a 55-year-old female patient with prior history of gastrointestinal neurofibromas who presented with abdominal pain. MR imaging revealed choledocholithiasis, gallbladder thickening, and marked biliary and pancreatic ductal dilation. The patient subsequently underwent cholecystectomy with choledochoduodenostomy. Histologic evaluation of the gallbladder showed diffuse expansion of the mucosa with S100p positive cells with spindly nuclei and indistinct cytoplasmic borders and diagnosis of MSCH of the gallbladder was rendered.

Mesenchymal tumours of the gastrointestinal tract

Mesenchymal tumours represent a heterogenous group of neoplasms encopassing benign, intermediate malignancy, and malignant entities. Sarcomas account for approximately 1% of human malignancies. In consideration of their rarity as well as of intrinsic complexity, diagnostic accuracy represents a major challenge. Traditionally, mesenchymal tumours are regarded as lesions the occurrence of which is mostly limited to somatic soft tissues. However, the occurrence of soft tissue tumours at visceral sites represent a well recognized event, and the GI-tract ranks among the most frequently involved visceral location. There exist entities such as gastrointestinal stromal tumours (GIST) and malignant gastointestinal neuroectodermal tumors that exhibit exquisite tropism for the GI-tract. This review will focus also on other relevant clinico-pathologic entities in which occurrence at visceral location is not at all negligible.

Recent Advances in Digestive Tract Tumors: Updates From the 5th Edition of the World Health Organization "Blue Book"

CONTEXT.—

The World Health Organization Classification of Tumours: Digestive System Tumors, 5th edition, was published in 2019 and shows several impactful changes as compared with the 4th edition published in 2010. Changes include a revised nomenclature of serrated lesions and revamping the classification of neuroendocrine neoplasms. Appendiceal goblet cell adenocarcinoma is heavily revised, and intrahepatic cholangiocarcinoma is split into 2 subtypes. New subtypes of colorectal carcinoma and hepatocellular carcinoma are described. Precursor lesions are emphasized with their own entries, and both dysplastic and invasive lesions are generally recommended to be graded using a 2-tier system. Hematolymphoid tumors, mesenchymal tumors, and genetic tumor syndromes each have their own sections in the 5th edition. New hematolymphoid lesions include monomorphic epitheliotropic intestinal T-cell lymphoma; duodenal-type follicular lymphoma; intestinal T-cell lymphoma, not otherwise specified; and indolent T-cell lymphoproliferative disorder of the gastrointestinal tract. This paper will provide an in-depth look at the changes in the 5th edition as compared with the 4th edition.

OBJECTIVE.—

To provide a comprehensive, in-depth update on the World Health Organization classification of digestive tumors, including changes to nomenclature, updated diagnostic criteria, and newly described entities.

DATA SOURCES.—

The 5th edition of the World Health Organization Classification of Tumours: Digestive System Tumours, as well as the 4th edition.

CONCLUSIONS.—

The World Health Organization has made many key changes in its newest update on tumors of the digestive system. Pathologists should be aware of these changes and incorporate them into their practice as able or necessary.

Mucosal Schwann Cell Hamartoma of the Gall Bladder

Mucosal Schwann cell hamartoma (M-SCH) of the intestinal mucosa is a rare entity and incidental finding in histological examination. Histological characteristics are Schwannonian cell proliferation in lamina propria with S100-positivity. M-SCH-like lesion in the gall bladder is even rarer and is a recently reported entity. We report this extremely rare lesion in a cholecystectomy specimen of a 4-year-old boy, which makes it the youngest patient to be having M-SCH-like lesion in the gall bladder.

Multiple non-polypoid mucosal Schwann cell hamartomas presenting as edematous and submucosal tumor-like lesions: a case report

Background

Mucosal Schwann cell hamartomas are rare neurogenic tumors which present most commonly in the distal colon. They are usually discovered as small, single polyps in asymptomatic patients.

Case presentation

An asymptomatic 64-year-old man was referred to us after a 12 mm subepithelial lesion was discovered incidentally on screening colonoscopy. Follow-up colonoscopy conducted 2 months later revealed that the tumor had disappeared, leaving multiple edematous, submucosal tumor-like elevations presenting as skip lesions throughout the sigmoid colon. Lesions had elongated pits on magnifying endoscopy and were limited to the first layer on endoscopic ultrasound. Biopsies revealed unclearly delineated foci of spindle-shaped cells limited to the lamina propria. On immunohistochemistry, all lesions were positive for S-100 protein and negative for CD34, CD56, and neurofilament protein. The patient was diagnosed with multiple mucosal Schwann cell hamartomas of the sigmoid colon. He remains asymptomatic after 18 months of follow-up, but the lesions have also remained unchanged.

Conclusion

We report a case of multiple non-polypoid mucosal Schwann cell hamartomas. Endoscopic findings may assist in the differential diagnosis, particularly when presenting as non-polypoid, submucosal tumor-like lesions.

Mucosal Schwann cell hamartoma of the gastroesophageal junction: A series of 6 cases and comparison with colorectal counterpart

Mucosal Schwann cell hamartoma (MSCH) is an uncommon neural lesion characterized by an ill-defined proliferation of S100-positive Schwann cells in the lamina propria, with reported cases exclusively occurring in the colorectum. Here we describe the first series of MSCHs arising in the gastroesophageal junction (GEJ) and discuss their clinicopathologic features in comparison with their colorectal counterparts. We searched the UCLA pathology database from 01/2014 to 12/2018 to identify cases carrying the diagnosis of MSCH. A total of 48 cases (45 in-house, 3 consults) of colorectal MSCHs and 6 cases (1 in-house, 5 consults) of GEJ MSCHs were identified. For GEJ MSCHs, there were 4 males and 2 females with an average age of 70.2 years (range: 57-76 years). Clinical indications for endoscopy included history of gastroesophageal reflux disease (n = 2), heartburn (n = 2), dysphagia (n = 1), and iron deficiency anemia (n = 1). Endoscopic findings at the GEJ were available for 5 patients including irregular Z-line (n = 3), mild nodular carditis (n = 1), and normal (n = 1). None of them showed a polyp or nodule. The mean size of the lesion was 2.8 mm (range: 2-4 mm) microscopically. None of the colorectal or GEJ MSCH cases had an association with inherited syndromes. In conclusion, MSCH of the gastrointestinal tract is predominantly seen in the colorectum, but also infrequently seen in the GEJ. GEJ MSCH shares histologic and immunohistochemical features with its colorectal counterpart, but is usually an incidental finding with no endoscopically visible lesion. As there is no syndromic association with MSCH, additional treatment, work-up and follow-up are unnecessary.

Colonic Neurogenic Lesion: An Admixture of Mucosal Neurofibromatous Lesion and Submucosal Ganglioneuromatous Lesion With Transition

Benign neural tumors or tumor-like lesions are rarely detected in the gastrointestinal tract. In this article, we present the case of a neural lesion of the sigmoid colon, which was incidentally detected in a 68-year-old man treated with laparoscopic low anterior resection for an advanced carcinoma of the rectosigmoid junction. Within the resected specimen, a submucosal tumor-like protruding lesion was found in the sigmoid colon. Histologically, the growth was composed of mucosal neurofibromatous and submucosal ganglioneuromatous lesions, between which there was transition. Immunohistochemical analysis revealed a rupture of the perineurium in the area of transition, along with a proliferation of Schwann cells and supporting cells extending into the deep mucosa. This transition indicated that the mucosal and submucosal lesions comprised a single lesion, and that a diagnosis of neurofibroma or ganglioneuroma would be inadequate in this case. Because we could not classify it as an established single entity, we diagnosed the mass as an unclassifiable colonic neurogenic lesion. In summary, we report the case of an extremely rare occurrence of an unclassifiable colonic neurogenic lesion comprising an admixture of transitioning mucosal neurofibromatous and submucosal ganglioneuromatous lesions.

Spindle cell proliferations of the sigmoid colon, rectum and anus: a review with emphasis on perineurioma

A wide range of spindle cell proliferations are found uncommonly in the sigmoid colon, rectum and anus. They usually present as polyps, and include reactive lesions and benign and malignant neoplasms which may be primary or metastatic. They are less frequently described in the literature compared to those in the upper gastrointestinal tract, and may be underdiagnosed. The widespread use of sigmoidoscopy in symptomatic patients and bowel cancer screening programmes means that histopathologists must be aware of, and adopt a logical approach to, diagnosing spindle cell proliferations in biopsy and polypectomy specimens. This is particularly relevant given the strong association of some mesenchymal polyps with hereditary cancer syndromes. This review article will focus on perineurioma and the recent debate in relation to its overlap with fibroblastic polyp. The clinical, endoscopic, histological and immunohistochemical features of spindle cell proliferations which should be considered in the differential diagnosis of perineurioma will be discussed. There is also a brief reference to malignant spindle cell tumours of diagnostic importance.

Cecal Mucosal Myxoma: The First Report of a New Type of Mesenchymal Colon Polyp

Myxomas are benign mesenchymal neoplasms of unknown etiology that most commonly occur in the cardiac atrium; however, other reported sites include the skin, joints, skeletal muscles, maxillofacial bones, and sinonasal tract. Myxomas involving the gastrointestinal (GI) tract are rare and are limited to a few published case reports. We are presenting, to our knowledge, the first case report of a mucosal myxoma in the colon presenting as a colonic polyp. A 49-year-old woman underwent a screening colonoscopy and was found to have a 0.2-cm sessile polyp in the cecum. Histologically, the polyp was composed of bland spindled cells in the lamina propria set in a hypocellular, myxoid stroma. The lesion was relatively well-demarcated from the surrounding mucosa. The overlying colonic epithelium showed no dysplasia. S-100 immunohistochemical stain showed only focal nonspecific positivity, while CD34, CD117, SMA, EMA, and desmin were all negative. Alcian blue special stain showed positive staining, supporting the diagnosis of myxoma. Myxomas in the GI tract are very rare, with this being the first reported case of a polypoid colonic mucosal myxoma. Previous reports of GI myxomas are limited to examples in the stomach, small bowel, and one recently reported case in the colon, all of which were submucosal lesions and not limited to the mucosa. In some of the prior reports, the patients had synchronous cardiac atrial myxomas. Mucosal colonic myxoma represents a newly identified mesenchymal polyp of the colon and pathologists should be aware of this diagnostic entity.

Benign epithelioid peripheral nerve sheath tumour arising in the rectum: A cytological and histological description

A 57-year old man presented with a 3.6 cm submucosal rectal cystic mass detected on colonoscopy and MRI. The lesion was deroofed, with rectal cyst fluid and cyst wall received for examination. Smears contained atypical cells occurring singly and in small aggregates, with epithelioid and spindled cells with hyperchromatic nuclei. Occasional cells exhibited intranuclear cytoplasmic inclusions. The concurrent histopathology specimen from the rectal cyst wall showed good correlation with the cytologic findings. The lesion was confined to the muscularis propria, with predominantly epithelioid cells and occasional spindled forms arranged in sheets, nests, and trabeculae with intervening fibrillary and fibrous stroma. Mitotic figures were scant, with no atypical mitoses or necrosis. An extensive immunohistochemical panel was performed, showing strong and diffuse nuclear and cytoplasmic staining with S100 and moderate to strong intensity nuclear staining with SOX10, in keeping with a benign epithelioid peripheral nerve sheath tumour. The patient remains well 3 years following diagnosis, and two subsequent biopsies at the site show no evidence of recurrent disease. We herein provide the first cytologic description of this lesion, with histopathologic correlation and a brief review of other differential diagnostic possibilities.

Mucosal Schwann cell hamartomas do occur the gastric mucosa – report of two cases mimicking fundic gland polyps

Mucosal Schwann cell hamartomas (MSCHs) are recently characterized benign spindle cell lesions of the colon and rectum. There is only one report of MSCHs in the stomach (antrum). Herein, we present the first reports of MSCHs occurring in the fundic mucosa as lesions that endoscopically mimicked a typical fundic gland polyp. Case 1. A 56-year-old woman sought medical attention due to epigastric pain. A small polypoid lesion in the fundic mucosa was removed with an endoscopic impression of a fundic gland polyp. Case 2. A 66-year-old man sought medical attention due to epigastric pain. The patient underwent antral and corporal biopsies that showed mild non-active gastritis without Helicobacter pylori infection. Small polypoid lesions in the fundic mucosa were seen; one was removed with an endoscopic impression of the fundic gland polyp. At the microscope, both lesions were entirely intramucosal, ill-defined spindle cell aggregations, suggesting a fascicular growth pattern. Both lesions were strongly and diffusely positive for S100. Awareness of this lesion is relevant to avoid the diagnosis of other benign spindle cell lesions that are associated with familial syndromes.

Mucosal Schwann Cell Hamartoma of the Rectosigmoid Junction: A Rare Lesion Mimicking Mucosal Prolapse Syndrome and Other Neural Lesions

In this article, we report the case of a 40-year-old woman with a sessile polyp of the rectosigmoid junction that underwent endoscopic resection. The resected specimen showed spindle cell proliferation with eosinophilic cytoplasm between mucosal crypts, mimicking mucosal prolapse syndrome. However, these were immunohistochemically positive for S-100, indicating neural cell origin. As neural polypoid lesion of the rectum, neurofibroma, perineurioma, schwannoma, and mucosal Schwann cell hamartoma were in the differential diagnosis. Histology and additional immunohistochemistry confirmed mucosal Schwann cell hamartoma. Mucosal Schwann cell hamartoma of the rectosigmoid junction or rectum can be a histological mimic of mucosal prolapse syndrome and other S-100 positive neural cell lesions; however, the lesion in the present case was correctly diagnosed with histology and immunohistochemistry.

Case of colonic mucosal Schwann cell hamartoma and review of literature on unusual colonic polyps

Mucosal Schwann cell hamartomas (MSCH) are benign mesenchymal tumours rarely seen in the gastrointestinal tract. They occasionally present as incidental sessile polyps during colonoscopy. A 55-year-old asymptomatic female patient with a medical history of multiple sclerosis presented for a screening colonoscopy. A 5 mm low-risk tubular adenoma was noted in the caecum, and a second 5 mm polyp was found in the ascending colon. Histopathology of the ascending colon polyp showed proliferation of spindle cells without ganglion cells in the lamina propria. Immunohistochemical findings are compatible with an MSCH. Surveillance colonoscopy was scheduled in 5 years based on the presence of a single low-risk tubular adenoma.

Colonic perineurioma (benign fibroblastic polyp): case report and review of the literature

BACKGROUND

Colorectal perineuriomas are uncommon benign mucosal-based proliferations of mesenchymal cells that express perineurial markers, often associated with colonic crypts displaying a serrated/hyperplastic architecture. The vast majority of cases arise distal to the splenic flexure and have been described as sessile polyps. Using molecular analysis, BRAF mutations have been demonstrated in the serrated crypt epithelium. We report a new case of perineurioma presenting as a pedunculated polyp in the transverse colon, with prominent hemosiderin deposits in the uninvolved lamina propria that separated the perineurial proliferation from the surface epithelium, a previously unreported histological finding. By using immunohistochemistry, we demonstrated the presence of BRAF V600E mutated protein in the serrated crypt epithelium. In addition, a review of the literature on colorectal perineurioma is provided.

CASE PRESENTATION

A 5 mm pedunculated polyp was removed from the transverse colon of a 42 year old man who presented with epigastric pain, weight loss and rectal bleeding. A proliferation of uniform plump spindled cells expanded the lamina propria and separated serrated colonic crypts. The epithelial component closely resembled microvesicular hyperplastic polyp. Immunohistochemical stains for epithelial membrane antigen (EMA), glucose transporter 1 (GLUT1) and collagen IV were positive in the stromal proliferation. A mutation-specific monoclonal antibody directed against BRAF V600E showed positive cytoplasmic staining in the serrated crypt epithelium but not in the perineurial proliferation. Conspicuous hemosiderin deposition was seen in the inflamed lamina propria between the perineurial proliferation and the surface epithelium.

CONCLUSION

Although the majority of colorectal perineuriomas occur in the sigmoid colon and rectum and are described as sessile polyps, colorectal perineurioma can present as a pedunculated polyp proximal to the splenic flexure as described in this case. Conspicuous hemosiderin deposition can be seen in the superficial lamina propria. BRAF mutations are limited to the serrated crypt epithelium.

Neural and neurogenic tumours of the gastroenteropancreaticobiliary tract

Neural lesions occur uncommonly in the gastroenteropancreaticobiliary tract. However, due to the growing number of screening colonoscopy procedures, polypoid neural lesions of the colon are being recognised increasingly and range from benign tumours to high-grade malignant neoplasms. Morphological variability of neural tumours can be wide, although some entities share pathological features, and, as such, these lesions can be diagnostically challenging. We review the spectrum of pathology of neural tumours in the gastroenteropancreaticobiliary tract, with the goal of providing a practical approach for practising surgical pathologists.

[Mucosal Schwann cells hamartoma: Review of a recently described entity]

Neural lesions of the colon may be masses (schwannomas and neurofibromas) or, more frequently, small polyps including perineuromas, ganglioneuromas and granular cell tumors. Some neural lesions are associated with congenital syndromes (neurofibromatosis-1, multiple endocrine neoplasia-2B). Recently, a new entity has been described named mucosal Schwann cell hamartoma, consisting of an intramucosal neural proliferation; to date, less than forty cases have been reported. We report a further case in a patient from whom a polyp was extirpated during colonoscopy screening. Histologically, the polyp showed a lamina propia that contained spindle-shaped cells of neural aspect which could only be identified after a histochemical and immunohistochemical study.

Tactile Corpuscle-Like Bodies (Wagner-Meissner Corpuscles) of the Colorectum: A Series of 5 Cases

An increase in screening colonoscopies has led to the recent identification and description of several benign mesenchymal proliferations within the colon that may be sampled incidentally or as mucosal polyps. Tactile corpuscle-like bodies (TCLBs) (also known as Wagner-Meissner corpuscles) are Schwannian-derived specialized mechanosensors found in glabrous skin and some mucosal sites. TCLBs are not a normal component of gastrointestinal mucosa but they have been reported in the esophagus, stomach, gastroesophageal junction, and colorectum. Twenty-two cases of tactile corpuscle-like bodies (TCLBs) have been reported to date in the English literature. We herein present five additional cases of TCLBs, all within the colorectum. It is important to distinguish TCLBs from histologic mimics that are associated with inherited syndromes. TCLBs are typically incidental, and are entirely benign.

ALA-induced photodynamic effect on viability, apoptosis and secretion of S100 protein, secreted by colon cancer cells in vitro

BACKGROUND

S100 protein is a proven prognostic factor in cancers. In colorectal cancers, its secretion correlates with clinical stage of the disease. Photodynamic therapy (PDT) is used as a supporting therapy in treatment of this particular cancer. The main aim of our study was to estimate the effect of photodynamic therapy with 5-aminolevulinic acid (ALA) in sublethal doses (ALA-PDT) on the secretion of S100 protein by colon cancer cells.

METHODS

Investigations were performed on two colon cancer cell lines. The SW480 cell line is a culture containing locally malignant cancer. The SW620 line is characterized by high metastatic activity. Each line was exposed to different concentrations of photosensitizer's precursor-ALA, and various level of light radiation. Afterwards, cell viability, using MTT and LDH assays and apoptosis of both lines was assessed. Then measurement of S100 protein concentration was performed using a 2-step enzyme immunoassay.

RESULTS

After application of ALA PDT the S100 protein concentration was reduced by 27% in SW480 cell line and by 30% in SW620 cell line. At the same time there has been no increase in the concentration of S100 protein in cells exposed to the light alone. It was demonstrated that the more aggressive line SW620 releases higher levels of S100 proteins in comparison with the line SW480.

CONCLUSION

The outcome of this study presented beneficial effect of ALA-PDT on persistent colon cancer cells. This therapy leads to decrease of S100 protein concentration in both colon cancer cell lines: SW480 and SW620.

Synchronous mucosal Schwann-cell hamartomas in a young adult suggestive of mucosal Schwann-cell harmatomatosis: a case report

Background

Mucosal Schwann-cell hamartoma is a rare mesenchymal polyp that presents in the intestine. Despite lacking ganglion cells, it resembles a gastrointestinal ganglioneuroma.

Case presentation

We report a case of synchronous mucosal Schwann-cell hamartomas in a young male patient, who presented with a single discrete polyp in the mid-rectum and multiple polypoid mucosal lesions in the distal rectum.

Conclusion

To the best of our knowledge, this is the first report of a case of multiple mucosal Schwann-cell hamartomas.

Neurogenic polyps of the gastrointestinal tract: a clinicopathologic review with emphasis on differential diagnosis and syndromic associations

Primary neurogenic gastrointestinal polyps are encountered relatively frequently in routine pathology practice. They encompass a variety of neoplastic entities with clinical, morphologic, and molecular features that reflect the diversity of neural elements within the gastrointestinal system. Although most are benign and encountered incidentally, accurate diagnosis may have important clinical implications because of the associations of certain neurogenic polyps with familial syndromes or other conditions. We review the pathology of these polyps with an emphasis on the diagnostic challenges that they pose and on newly described subtypes.

Gastrointestinal tract spindle cell lesions--just like real estate, it's all about location

Interpretation of gastrointestinal tract mesenchymal lesions is simplified merely by knowing in which anatomic layer they are usually found. For example, Kaposi sarcoma is detected on mucosal biopsies, whereas inflammatory fibroid polyp is nearly always in the submucosa. Gastrointestinal stromal tumors (GISTs) are generally centered in the muscularis propria. Schwannomas are essentially always in the muscularis propria. Mesenteric lesions are usually found in the small bowel mesentery. Knowledge of the favored layer is even most important in interpreting colon biopsies, as many mesenschymal polyps are encountered in the colon. Although GISTs are among the most common mesenchymal lesions, we will concentrate our discussion on other mesenchymal lesions, some of which are in the differential diagnosis of GIST, and point out some diagnostic pitfalls, particularly in immunolabeling.

Wagner-Meissner–Like Corpuscles in Gastric Mucosa

Wagner-Meissner corpuscles are touch receptors that are located in dermal papillae and are usually absent in gastrointestinal mucosa. Wagner-Meissner–like corpuscles have been reported in association with benign neural neoplasm. A case of Wagner-Meissner–like corpuscles in endoscopically normal gastric mucosa biopsy of a 48-year-old woman is presented here. The corpuscles were positive for S-100 and clinical evidence of neurofibromatosis was negative. From a review of the literature, only 2 cases of tactile corpuscle-like structures in gastric mucosa are available.

Incidental finding of isolated colonic neurofibroma

Neurofibromatosis is a genetic disorder manifested by characteristic cutaneous lesions called neurofibromas. There are two distinct neurocutaneous syndromes named neurofibromatosis type 1 (also called von Recklinghausen disease or NF1) and neurofibromatosis type 2 (NF2). NF1 is by far the most common presentation and is caused by an autosomal dominant mutation in the NF1 gene mapped to chromosome 17q11.2. The literature shows that gastrointestinal involvement is noted in systemic neurofibromatosis in up to 25% of patients, but isolated intestinal neurofibromatosis is a very rare manifestation. We herein present the case of a 70-year-old woman who was diagnosed with an isolated colonic neurofibroma without any systemic signs of neurofibromatosis; only a few case reports of this condition have been published to date.

Tactoid body features in a Schwann cell hamartoma of colonic mucosa

BACKGROUND

Mesenchymal colorectal polyps are uncommon lesions, particularly those of neurogenic origin. We describe a mucosal Schwann cell hamartoma of the colon with tactoid features, so far reported in peripheral nerve sheath tumours, and address its differential diagnosis and clinical implications.

CASE PRESENTATION

A 72-year-old man underwent screening colonoscopy that presented a 5-mm polyp on distal sigmoid. Histologically, it displayed a lesion in the lamina propria comprising oval structures with tactoid features and bland spindle cells, entrapping adjacent crypts. No ganglion cells were seen. Spindle cells expressed only S-100 protein and vimentin.

DISCUSSION

Mucosal Schwann cell hamartoma was recently recognized as distinct from common (submucosal) colorectal Schwannomas and so far not associated to inherited syndromes. Thus, it should be considered in the differential diagnosis of look-alike lesions (eg, ganglioneuroma, neuroma, and neurofibroma) that may occur in the setting of inherited syndromes such as Cowden syndrome, multiple endocrine neoplasia-2B, and type 1 neurofibromatosis.

Mesenchymal Tumors of the Gastrointestinal Tract Other than GIST

Mesenchymal tumors involve the gastrointestinal (GI) tract more frequently than other visceral organs. Many such tumors are small, and are benign and increasingly being detected incidentally during colonoscopic screening. Some tumors show distinctive features at this site, such as schwannoma and clear cell sarcoma-like tumor of the GI tract. Without knowledge of these features, recognition of these tumor types can be difficult. This reviews addresses recent developments and diagnostic features of mesenchymal tumors of the GI tract other than gastrointestinal stromal tumor (GIST).

Mucosal schwann-cell hamartoma diagnosed by using an endoscopic snare polypectomy

Colorectal polyps of mesenchymal origin are a rare group of colorectal disorders. A "mucosal Schwann-cell hamartoma," which is one type of polypoid lesion that originates from the mesenchyme, is a newly-proposed disease entity to be distinguished from the neurofibromas found in type-1 neurofibromatosis. This lesion is composed of pure Schwann-cell proliferation in the lamina propria and shows diffuse immunoreactivity for the S-100 protein. We report a case of a polypoid lesion of the colon with the features of this recently-proposed disease entity.

Schwannoma of the rectum: A case report and literature review

Schwannoma is a tumor originating from the Schwann cells. Gastrointestinal schwannomas are uncommon stromal tumors of the intestinal tract and, in particular, rectal schwannomas are extremely rare. In fact, it is well established that schwannomas appear more frequently in the stomach and in the small intestine, while location in the colon or in the rectum is uncommon. Reading the literature, only few cases of rectal schwannoma have been reported. Their diagnosis is confirmed by the immunohistochemical panel (S-100 protein). When these tumors are located in the colon and in the rectum, radical excision with wide margins is mandatory, due to their tendency to recur locally or become malignant, if left untreated. In the present study, we describe a case of a rectal schwannoma occured in a 72-year-old man, presented as a small polypoid lesion, which was successfully removed in toto by hot-biopsy, during the same endoscopy, due to the dimensons. No recurrence of the lesion was observed after 6 mo of follow-up.

Pathology of peripheral nerve sheath tumors: diagnostic overview and update on selected diagnostic problems

Peripheral nerve sheath tumors are common neoplasms, with classic identifiable features, but on occasion, they are diagnostically challenging. Although well-defined subtypes of peripheral nerve sheath tumors were described early in the history of surgical pathology, controversies regarding the classification and grading of these tumors persist. Advances in molecular biology have provided new insights into the nature of the various peripheral nerve sheath tumors, and have begun to suggest novel targeted therapeutic approaches. In this review, we discuss current concepts and problematic areas in the pathology of peripheral nerve sheath tumors. Diagnostic criteria and differential diagnosis for the major categories of nerve sheath tumors are proposed, including neurofibroma, schwannoma, and perineurioma. Diagnostically challenging variants, including plexiform, cellular and melanotic schwannomas are highlighted. A subset of these affects the childhood population, and has historically been interpreted as malignant, although current evidence and outcome data suggest they represent benign entities. The growing current literature and the author's experience with difficult to classify borderline or "hybrid tumors" are discussed and illustrated. Some of these classification gray zones occur with frequency in the gastrointestinal tract, an anatomical compartment that must always be entertained when examining these neoplasms. Other growing recent areas of interest include the heterogeneous group of pseudoneoplastic lesions involving peripheral nerve composed of mature adipose tissue and/or skeletal muscle, such as the enigmatic neuromuscular choristoma. Malignant peripheral nerve sheath tumors (MPNST) represent a diagnostically controversial group; difficulties in grading and guidelines to separate "atypical neurofibroma" from MPNST are provided. There is an increasing literature of MPNST mimics which neuropathologists must be aware of, including synovial sarcoma and ossifying fibromyxoid tumor. Finally, we discuss entities that are lacking from the section on cranial and paraspinal nerves in the current WHO classification, and that may warrant inclusion in future classifications. In summary, although the diagnosis and classification of most conventional peripheral nerve sheath tumors are relatively straightforward for the experienced observer, yet borderline and difficult-to-classify neoplasms continue to be problematic. In the current review, we attempt to provide some useful guidelines for the surgical neuropathologist to help navigate these persistent, challenging problems.

Benign gastrointestinal mesenchymal BUMPS: a brief review of some spindle cell polyps with published names

CONTEXT

There are several benign, predominantly spindle cell, mesenchymal proliferations involving the mucosa and/or submucosa in the gut, which present as polyps and pathologists see as polypectomy specimens. These include perineuriomas, Schwann cell nodules, ganglioneuromas, leiomyomas of the muscularis mucosae, inflammatory fibroid polyps, and granular cell tumors.

OBJECTIVES

To evaluate these mesenchymal polyps for their morphologic, immunohistochemical, ultrastructural, and molecular characteristics and to determine some of their associations.

DATA SOURCES

Personal observations based on years of analyzing endoscopic biopsies and a review of the world's literature.

CONCLUSIONS

These polyps do surface every so often. There is significant literature covering inflammatory fibroid polyps and granular cell tumors, but there is little literature about the other entities.

Schwann cell hamartoma: case report

Background

Colorectal polyps of mesenchymal origin represent a small percentage of gastrointestinal (GI) lesions. Nevertheless, they are encountered with increasing frequency since the widespread adoption of colonoscopy screening.

Case presentation

We report a case of a small colonic polyp that presented as intramucosal diffuse spindle cell proliferation with a benign cytological appearance, strong and diffuse immunoreactivity for S-100 protein, and pure Schwann cell phenotype. Careful morphological, immunohistochemical and clinical evaluation emphasize the differences from other stromal colonic lesions and distinguish it from schwannoma, a circumscribed benign nerve sheath tumor that rarely arises in the GI tract.

Conclusion

As recently proposed, this lesion was finally described as mucosal Schwann cell hamartoma.

Gastrointestinal Mesenchymal Neoplasms other than Gastrointestinal Stromal Tumors: Focusing on Their Molecular Aspects

Gastrointestinal (GI) mesenchymal tumors other than gastrointestinal stromal tumor (GIST) are rare neoplasms, but they often enter the differential diagnosis of more common GI lesions. Some of these mesenchymal tumors in the GI tract have well understood molecular pathologic aspects, including desmoid tumors, inflammatory myofibroblastic tumor (IMT), clear cell sarcoma (CCS), inflammatory fibroid polyp (IFP), and synovial sarcoma (SS). Molecular pathology is fast becoming a mainstream focus in laboratories because it aids in the precise classification of tumors, may be prognostic, and may help predict response to therapy. The following review is not intended as an exhaustive summary of all mesenchymal tumors that have been reported to involve the GI tract, but instead will highlight the current knowledge of the most important non-GIST GI mesenchymal neoplasms, focusing on those tumors with well-characterized molecular pathology and how the molecular pathologic features impact current diagnostic, therapeutic, and prognostic standards.

Benign serrated colorectal fibroblastic polyps/intramucosal perineuriomas are true mixed epithelial-stromal polyps (hybrid hyperplastic polyp/mucosal perineurioma) with frequent BRAF mutations

Colorectal fibroblastic polyp and intramucosal perineurioma are 2 synonyms for a recently described benign mucosal lesion with a predilection for the rectosigmoid colon. These lesions are characterized by aggregates of bland spindled cells separating and distorting mucosal crypts. The latter frequently showed a serrated architecture. The pathogenesis of fibroblastic polyp/intramucosal perineurioma and the nature of serrated crypts observed in them are poorly understood. We analyzed the clinicopathological features of 29 fibroblastic polyps and investigated them for the first time for mutations known to be involved in serrated colorectal epithelial polyps (BRAF, KRAS, and PIK3CA). Patients were 23 women and 6 men with a mean age of 64 years (range: 47 to 84 y). All lesions represented asymptomatic solitary polyps (mean size 3.5 mm) localized predominantly in the rectosigmoid colon (81%). Hyperplastic polyps, classical adenoma, and sessile serrated adenoma/lesion coexisted in 12 (44%), 12 (44%), and 5 (17%) patients, respectively. All lesions showed irregular aggregates of bland spindled cells separating and distorting mucosal crypts. Serrated (hyperplastic) crypts were observed on the top or contiguous with the lesion in all cases. Immunohistochemistry revealed expression of at least one perineurial cell marker (epithelial membrane antigen, claudin-1, and glucose transporter-1) in 26 out of 27 lesions (96%), but expression of CD34 was less common (8 of 27; 30%). Immunostaining for hMLH1 showed a normal nuclear expression. Molecular analysis in 22 cases showed V600E BRAF mutation in 14 cases (63%) and KRAS mutation in 1 (4%). The remainder were wild-type for all 3 genes. Our results indicate that serrated fibroblastic polyps/intramucosal perineuriomas represent a unique type of mixed epithelial-stromal polyps (hybrid hyperplastic polyp/mucosal perineurioma). The perineurial stromal component might be derived from modified pericryptic fibroblasts as a consequence of a yet poorly understood epithelial-stromal interaction.