Multiple small intestinal stromal tumors with skeinoid fibers in association with neurofibromatosis 1 (von Recklinghausen's disease)

Clinical Presentation and Treatment of Gastrointestinal Stromal Tumors

Aims and background

Gastrointestinal stromal tumors (GISTs), although rare, are the most common mesenchymal neoplasms affecting the gastrointestinal tract. We present our experience in the treatment of localized and metastatic disease and a review of literature.

Patients and methods

Nine patients were observed from April 2002 to July 2004. Eight tumors were in the gastric area and J was in the small bowel. In 5 cases, complete surgical removal was performed, and none of these patients underwent adjuvant therapy. The remaining 4 cases, with locally advanced or recurrent disease, were treated with imatinib.

Results

The patients with localized disease treated only by surgery did not relapse. In the patients with locally advanced or metastatic disease treated by imatinib, we observed 3 partial responses, and one case was not assessable because he had no measurable disease. In 2 of 3 responders, it was possible to perform a new radical surgery.

Conclusions

Our series is too small to draw any conclusion. According to our review of the literature, surgery remains the standard treatment for non-metastatic GISTs. Imatinib mesylate represents a major breakthrough in the treatment of advanced GISTs and is the first effective systemic therapy for the disease.

Neurofibromatosis 1 presenting with multiple duodenal GISTS associated with a somatostatin-producing D cell neoplasm

The co-existence of a duodenal somatostatin-producing D cell neoplasm and multiple duodenal gastrointestinal stromal tumours (GISTs) in a 61-year-old woman with neurofibromatosis type 1 is reported. Histologically, the D cell neoplasm showed a glandular pattern with psammoma bodies and was metastatic to regional lymph nodes and liver at the time of surgery. Tumour cells were monomorph and showed intense and diffuse immunoreactivity for somatostatin, focal positivity for calcitonin, while were negative for other gastroenteropancreatic hormones including insulin, glucagon, pancreatic polypeptide, serotonin and gastrin. Four submucosal and subserosal GISTs, ranging from 5 to 15 mm in diameter, were composed of uniform spindle-shaped cells lacking mitoses and contained numerous skeinoid fibres. The tumours were positive for CD117, DOG1, vimentin and CD34 and did not have KIT or PDGFRA mutations. The clinical and pathological importance of this unusual association is discussed.

Treatment of gastrointestinal stromal tumor: focus on imatinib mesylate

Gastrointestinal stromal tumor (GIST) is a rare primary neoplasm of the gastrointestinal tract, mesentery, or omentum. In the past, surgery has been the only effective treatment. The diagnosis and treatment of GIST has been revolutionized over the past decade, since expression of the receptor tyrosine kinase KIT was shown to occur on these tumors. Mutations in this proto-oncogene commonly cause constitutive activation of the KIT tyrosine kinase receptor, an important factor in the pathogenesis of the disease. The development of specific tyrosine kinase inhibitors, such as imatinib mesylate, has led to a breakthrough in the treatment of advanced GIST. Treatment with this drug has led to significant improvements in survival, with overall response rates in excess of 80%. Side effects are common, but usually manageable. The success of this drug has led to further trials investigating its use in the pre- and postoperative situation. This review summarizes the current knowledge of GIST and imatinib treatment and possible future developments.

Gain-of-Function Mutations of Receptor Tyrosine Kinases in Gastrointestinal Stromal Tumors

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors in human gastrointestinal tract. We first found that most GISTs expressed KIT, a receptor tyrosine kinase encoded by protooncogene c-kit and that approximately 90% of the sporadic GISTs had somatic gain-of-function mutations of the c-kit gene. Since both GISTs and interstitial cells of Cajal (ICCs) were double-positive for KIT and CD34, GISTs were considered to originate from ICCs or their precursor cells. We also found that germline gain-of-function mutations of the c-kit gene resulted in familial and multiple GISTs with diffuse hyperplasia of ICCs as the preexisting lesion. Moreover, we found that about half of the sporadic GISTs without c-kit gene mutations had gain-of-function mutations of platelet-derived growth factor receptor alpha (PDGFRA) gene that encodes another receptor tyrosine kinase. Imatinib which is known to inhibit constitutively activated BCR-ABL tyrosine kinase in chronic myelogenous leukemia also inhibits constitutive activation of mutated KIT and PDGFRA, and is now being used for metastatic or unresectable GISTs as a molecular target drug. Mutational analyses of c-kit and PDGFRA genes are considered to be significant for prediction of effectiveness of imatinib and newly developed/developing other agents on GISTs. Some mouse models of familial and multiple GISTs have been genetically created, and may be useful for further investigation of GIST biology.

Periampullary and duodenal neoplasms in neurofibromatosis type 1: two cases and an updated 20-year review of the literature yielding 76 cases

BACKGROUND

Patients with neurofibromatosis type 1 (NF1) are at increased risk to develop tumors throughout the gastrointestinal tract, including neuromas, gastrointestinal stromal tumors (GIST), and periampullary somatostatin-rich carcinoids. Here, we briefly describe two male patients with NF1 and review the recent literature on this topic.

METHODS

Databases for PubMed and MEDLINE were searched for English-language articles since 1989 using a list of keywords, as well as references from review articles.

RESULTS

The results generated by the search yielded 50 articles and 74 cases. Patients most commonly presented with jaundice, weight loss, GI bleeding, or anemia. The mean age at presentation was 47.9 years, with 59% of patients being female. Mean tumor size was 3.8 cm (range 0.9-27 cm). Tumor location was the duodenum (60%), ampulla (31%), pancreas (5%), or bile duct/gallbladder (4%). Tumor type was reported as somatostatinoma (40%), GIST (34%), adenocarcinoma (8%), carcinoid (6%), neurofibroma (5%), schwannoma (4%), or gangliocytic paraganglioma (3%). Treatment included classic Whipple procedure (42%), local excision (25%), pylorus-preserving pancreaticoduodenectomy (17%), and other resection (6%). Mean follow-up was 31 months postresection (range 0-99 months): 75% of patients were alive with no evidence of disease.

CONCLUSIONS

These results underscore the importance of a thorough evaluation for tumors in NF1 patients with gastrointestinal symptoms, as well as subsequent surgical management when findings suggest a tumor in the periampullary region, as resection remains the mainstay of treatment.

Life-threatening gastrointestinal haemorrhage in Von Recklinghausen's disease

Neurofibromatosis Type I (NF-1), also known as Von Recklinghausen's disease, is a common disorder, but gastrointestinal manifestations are rare and can be associated with severe complications and malignancy. We describe a case of multiple intestinal tumours, which presented as major per-rectal bleeding and was diagnosed by laparotomy. Presenting symptoms of this condition are usually non-specific, but the risk of malignancy and perforation should allow for a high index of suspicion in patients with NF-1 presenting with gastrointestinal symptoms. We present this case as a reminder that blood loss from the bowel in Von Recklinghausen's disease may be life-threatening, requiring immediate surgery to control haemorrhage.

The molecular pathogenesis of gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) are clinically diagnosed by positive immunohistochemical staining of KIT, a type III receptor tyrosine kinase. Most GISTs contain gain-of-function, ie, oncogenic mutations in c-KIT or in platelet-derived growth factor receptor-alpha (PDGFR-alpha), which appears to be the major initiating event that drives the pathogenesis for GIST. Furthermore, mutations in either of these genes appear to be required for tumor growth and progression. This scenario can be thought of as "oncogenic addiction" and is one of the major reasons why some GISTs respond significantly to therapies that target these mutant receptors. In addition to mutations in c-KIT or PDGFR-alpha, genomic alterations contribute to disease progression. Moreover, GISTs that harbor different c-KIT or PDGFR-alpha mutations have different molecular signatures at the level of gene expression, which further contributes to the complexity of GIST biology and variable responses to treatment. This article will discuss the molecular basis of pathogenesis and genetic and genomic alterations that contribute to GIST tumorigenesis and disease progression as well as the heterogeneity of this disease.

Gastrointestinal stromal tumors in a cohort of Chinese patients in Hong Kong

AIM: To investigate the prevalence and clinical pattern of gastrointestinal stromal tumors (GISTs) in Hong Kong Chinese, and to assess the impact of introduction of CD117 on the disease incidence.

METHODS: From the database of the Department of Pathology of Yan Chai Hospital, 47 patients, with GISTs from September 1995 to December 2003 were included in this study. Ten GISTs were diagnosed before the introduction of CD117. The clinical features, tumor characteristics, and treatment were analyzed. Factors predicting tumor related death or recurrence were studied with Cox proportional hazard model.

RESULTS: The patients included 26 males and 21 females, with a mean age of 66.6 years (SD 13.1, range 29-87 years). The estimated prevalence of GISTs was 13.4-15.6 per 100 000 people, with an annual incidence of 1.68-1.96 per 100 000 people. The annual incidence of GISTs before and after the introduction of CD117 was 1.1 per 100 000 people and 2.1 per 100 000 people respectively. Stomach (34 patients, 72.3%) was the most common location for the tumor, followed by the small intestine (8 patients, 17.0%), esophagus (2 patients, 4.3%), omentum (2 patients, 4.3%) and colon (1 patient, 2.1%). Thirty-one patients (66%) had complete tumor resection. Eleven out of 16 deaths (23%) were tumor-related. The median survival time was 26 mo. Five-year survival rate was 61.3%. The significant factors associated with tumor-related death or recurrence were incomplete resection, tumor size 5 cm or above, invasion to the adjacent organ or presence of metastasis.

CONCLUSION: The incidence of GIST in Hong Kong is comparable to that in the United States but lower than that in Finland. The true incidence of GISTs could be underestimated before the introduction of CD117. Incomplete resection, tumor size 5 cm or above, invasion to the adjacent organ or presence of metastasis are factors predicting tumor-related death or recurrence.

Pathology of gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GIST) are the most common mesenchymal tumors in the gastrointestinal tract. It was found that most GIST expressed KIT, a receptor tyrosine kinase encoded by protooncogene c-kit. In normal gastrointestinal wall, KIT is expressed by interstitial cells of Cajal (ICC), which are a pacemaker for autonomous gastrointestinal movement. Because both GIST and ICC are double-positive for KIT and CD34, and because familial and multiple GIST appear to develop from diffuse hyperplasia of ICC, GIST are considered to originate from ICC or their precursor cells. It was also found that approximately 90% of the sporadic GIST have somatic gain-of-function mutations of the c-kit gene, and that the patients with familial and multiple GIST have germline gain-of-function mutations of the c-kit gene. These facts strongly suggest that the c-kit gene mutations are a cause of GIST. Approximately half of the sporadic GIST without c-kit gene mutations were demonstrated to have gain-of-function mutations in platelet-derived growth factor receptor-alpha (PDGFRA) gene that encodes another receptor tyrosine kinase. Because KIT is immunohistochemically negative in a minority of GIST, especially in PDGFRA gene mutation-harboring GIST, mutational analyses of c-kit and PDGFRA genes may be required to diagnose such GIST definitely. Imatinib mesylate was developed as a selective tyrosine kinase inhibitor. It inhibits constitutive activation of mutated KIT and PDGFRA, and is now being used for KIT-positive metastatic or unresectable GIST as a molecular target drug. Confirmation of KIT expression by immunohistochemistry is necessary for application of the drug. The effect of imatinib mesylate is different in various types of c-kit and PDGFRA gene mutations, and the secondary resistance against imatinib mesylate is often acquired by the second mutation of the identical genes. Mutational analyses of c-kit and PDGFRA genes are also significant for prediction of effectiveness of drugs including newly developed agents.

Gastrointestinal stromal tumors in patients with neurofibromatosis 1: a clinicopathologic and molecular genetic study of 45 cases

Gastrointestinal stromal tumors (GISTs), the specific KIT- or PDFGRA-signaling driven mesenchymal tumors, most commonly occur sporadically, but there seems to be some increased tendency for these tumors to develop in patients with neurofibromatosis 1 (NF1). The clinicopathologic profile, KIT, and PDGFRA mutation status and long-term prognosis of patients with GIST in NF1 are incompletely characterized. In this study, we analyzed 45 patients who had NF1 and GIST. There were 26 females and 19 males with a median age of 49 years (10 years lower than the median age of GIST patients in general). A great majority of tumors occurred in the jejunum or ileum, with multiple tumors occurring in 28 cases. Ten patients had a duodenal and one had a gastric GIST. The most common presentations were gastrointestinal bleeding and anemia, and many patients had intermittent bleeding over several years. The majority of the tumors were small and mitotically inactive; only 7 had mitotic activity >5/50 HPFs and 15 tumors were >5 cm. Associated Cajal cell hyperplasia was common. One patient had an intraabdominal peri-intestinal neurofibroma. Five of 35 patients with follow-up died of metastatic disease; all of these had a tumor >5 cm, mitotic rate >5/50 HPFs, or both; three of these tumors were located in the duodenum. The presence of multiple small tumors was not associated with progressive disease. Most patients with long-term follow-up enjoyed a good prognosis; 2 died of other NF1-associated tumors (malignant peripheral nerve sheath tumors, brain tumor). None of the 16 tumors from 15 patients had a KIT exon 9, 11, 13, or 17 or PDGFRA exon 12 or 18 mutation as is typically seen in sporadic GISTs, indicating that GISTs in NF1 patients have a different pathogenesis than sporadic GISTs.

Multiple gastric stromal tumors in a child without syndromic association lacks common KIT or PDGFRalpha mutations

A diagnosis of multiple gastric stromal tumors that were nonmetastatic at presentation was made in an 11-year-old girl who presented with hematemesis. Gastrointestinal stromal tumor (GIST) is a rare diagnosis in childhood and reported multiple lesions are generally seen in the context of familial disease, occasionally with syndromic associations. Although there are no reports of genetic mutation in cases of pediatric GIST, very many cases of multiple GISTs investigated on a molecular level have shown germline KIT or platelet-derived growth factor receptor-alpha mutation; these were familial cases. Despite the negative family history in our patient, the multiplicity of lesions in such a young patient raised concern for a genetic predisposition and prompted extensive molecular workup. Repeat evaluation of distinct aliquots of tumor tissue by polymerase chain amplification followed by sequence analysis of selected coding sequences of KIT and platelet-derived growth factor receptor-alpha previously shown to harbor mutations in GIST, yielded no evidence of even a somatic mutation. This clinically unique case is discussed in the context of a literature review.

NF1-associated gastrointestinal stromal tumors have unique clinical, phenotypic, and genotypic characteristics

Gastrointestinal stromal tumors (GIST) have been reported to occasionally occur in patients with neurofibromatosis type 1 (NF1). This study aims to describe the phenotypic and genotypic characteristics of GIST in NF1 patients and attempts to elucidate the relationship between them. We analyzed GIST arising in 15 NF1 patients (8 males and 7 females, 19-82 years of age). Eleven patients had multiple GISTs (3 to >100 tumors) ranging from 1 mm to 10 cm in size and predominantly involving the small intestine including the duodenum. Tumors were symptomatic in 8 patients and incidental findings in the remaining 7 patients. Microscopically, the tumors cells were typically spindled and the mitotic rate low; 9 patients had tumors classified as very low or low risk and 6 as intermediate risk GIST. Nine patients were treated surgically and none developed metastases or died of disease. Immunohistochemical stains for CD117 were strongly positive in 47 of 50 GIST; they also accentuated hyperplastic foci (diffuse and focal) of the interstitial cells of Cajal that were often associated with microscopic GIST in the surrounding intestinal muscle wall. No KIT or PDGFRA mutations were detected in 24 GIST from 12 patients using dHPLC analysis and DNA sequencing. We conclude that patients with NF1 have a high risk of developing GIST. NF1-associated GIST are also phenotypically and genotypically distinct from sporadic GIST, indicating that different pathogenetic mechanisms are involved in their evolution.

Gastrointestinal stromal tumors of neurofibromatosis type I (von Recklinghausen's disease)

Gastrointestinal stromal tumor (GIST), as well as the hyperplastic lesions of intestinal neural tissue and its supporting structures, is a gastrointestinal complication of type 1 neurofibromatosis (NF1) (von Recklinghausen's disease). In the present study, we analyzed the histologic and immunohistochemical features, and the c-kit and PDGFRA gene mutations of 36 GISTs derived from 9 NF1 patients. Distinctively, multiple GISTs arose preferentially in the small intestine. The histologic features of NF1-associated GISTs are almost similar to those of non-NF1 GISTs, but characteristically most of the NF1-associated GISTs contained skeinoid fibers. Thirty-three GISTs (92%) showed immunoreactivity for KIT, and 23 tumors (64%) showed diffuse or mosaic-like immunoreactivity for S-100 protein. Hyperplasic lesions, which may be the hyperplasia of interstitial cells of Cajal, were observed around some GISTs. Exons 9, 11, 13, and 17 of the c-kit gene and exons 12 and 18 of the PDGFRA gene were amplified and directly sequenced. Point mutations of c-kit gene or PDGFRA gene were identified only in three (8%) and two (6%) tumors, respectively. NF1-associated GISTs, showing the dual differentiation of interstitial cells of Cajal and Schwann cells, develop in close association with the myenteric nerve structure of gastrointestinal tract of NF1 patients. The point mutations of c-kit and PDGFRA gene may play a limited role in the tumorigenesis of NF1-associated GISTs.

Multiple gastrointestinal stromal tumors in type I neurofibromatosis: a pathologic and molecular study

Multiple gastrointestinal stromal tumors typically occur in familial form associated with KIT receptor tyrosine kinase or platelet-derived growth factor receptor-alpha (PDGFRA) germline mutations, but may also develop in the setting of type 1 neurofibromatosis. The molecular abnormalities of gastrointestinal stromal tumors arising in neurofibromatosis have not been extensively studied. We identified three patients with type 1 neuro-fibromatosis and multiple small intestinal stromal tumors. Immunostains for CD117, CD34, desmin, actins, S-100 protein, and keratins were performed on all of the tumors. DNA was extracted from representative paraffin blocks from separate tumor nodules in each case and subjected to a nested polymerase chain reaction, using primers for KIT exons 9, 11, 13, and 17 and PDGFRA exons 12 and 18, followed by direct sequencing. The mean patient age was 56 years (range: 37-86 years, male/female ratio: 2/1). One patient had three tumors, one had five, and one had greater than 10 tumor nodules, all of which demonstrated histologic features characteristic of gastrointestinal stromal tumors and stained strongly for CD117 and CD34. One patient died of disease at 35 months, one was disease free at 12 months and one was lost to follow-up. DNA extracts from 10 gastrointestinal stromal tumors (three from each of two patients and four from one patient) were subjected to polymerase chain reactions and assessed for mutations. All of the tumors were wild type for KIT exons 9, 13, and 17 and PDGFRA exons 12 and 18. Three tumors from one patient had identical point mutations in KIT exon 11, whereas the other tumors were wild type at this locus. We conclude that, although most patients with type 1 neurofibromatosis and gastrointestinal stromal tumors do not have KIT or PDGFRA mutations, KIT germline mutations might be implicated in the pathogenesis of gastrointestinal stromal tumors in some patients.

SURGERY FOR GASTROINTESTINAL STROMAL TUMOUR IN THE POST-IMATINIB ERA

Gastrointestinal stromal tumour (GIST) is a rare tumour. Historically, surgery has been the only effective treatment. The prognosis of patients with gastrointestinal stromal tumour is poor. Even after apparently 'curative' surgical resection more than 50% of patients relapse. The development of an effective novel targeted therapy against GIST (imatinib mesylate) is a success story of molecular biology that has dramatically altered the management of patients with these tumours. However, as follow up of patients who have initially responded to imatinib has increased, it has become evident that such hopes of cure were premature because responses to imatinib are of limited duration. Unresolved issues include the role of imatinib as an induction (neo-adjuvant) therapy prior to surgery, or as adjuvant treatment after surgery, the role of surgery in patients with a differential or partial response and the role of surgery in patients with isolated metastatic disease. In the present paper the biology and natural history of GIST are reviewed, and the complexities of surgical management that exist in the context of an effective, but not curative, biological therapy, are addressed.

Gastrointestinal Neurofibromatosis: An Unusual Cause of Gastric Outlet Obstruction

Neurofibromatosis type-1 (NF-1), also known as von Recklinghausen disease, is a common autosomal dominant condition occurring in approximately 1/3000 births. NF-1 is known to be associated with gastrointestinal neoplasms in 2–25 per cent of patients. We report the first case of gastric outlet obstruction with perforation caused by neurofibroma in a patient with NF-1. The literature is reviewed, examining 61 previously reported cases of noncarcinoid gastrointestinal (GI) neoplasms in patients with NF-1 for symptoms, location, and types of neoplasms. Neoplasms were located most often in the small intestine (72%). Neurofibromas, found in 52 per cent of patients, were the most frequently diagnosed benign neoplasms followed by leiomyomas (13%), ganglioneurofibromas (9.8%), and gastrointestinal stomal tumor (GIST) (6.5%). Adenocarcinoma was present in 23 per cent of patients. Patients with NF-1 and GI symptoms are at risk for gastrointestinal neoplasms from which symptomatic patients are likely to experience significant morbidity.

Expression and mutation of c-kit gene in gastrointestinal stromal tumors

AIM: To investigate the expression and mutation of c-kit gene and its correlation with the clinical pathology and prognosis of gastrointestinal stromal tumors (GISTs).

METHODS: A total of 94 cases of GISTs, 10 leiomyomas and 2 schwannomas were studied for the expression of KIT by immunohistochemistry. The c-kit gene mutations in exon 11 of these specimens were detected by PCR-SSCP technique.

RESULTS: Of the 94 cases of GISTs, 91 (96.8%) expressed the KIT protein. Leiomyomas and schwannomas were negative for KIT. The c-kit gene mutations of exon 11 were found in 38 out of the 94 cases of GISTs (40.4%). The mutations involved point mutations (Val560-Asp, Ile563-Met), del 557-559 and 579ins12. No mutations were detectable in benign GISTs, leiomyomas or schwannomas. The patients with mutation-positive GISTs showed more frequent recurrences, invasion and metastasis in adjacent tissues than those with mutation-negative ones.

CONCLUSION: KIT is a useful marker for diagnosis of GISTs. Mutation of the c-kit gene may play a significant role in the pathogenesis of GISTs and may be associated with poor prognosis in patients with GISTs.

Management of malignant gastrointestinal stromal tumours

Gastrointestinal stromal tumours (GISTs) are the most common form of mesenchymal tumour of the gastrointestinal tract. Clinically, they range from small indolent tumours curable with surgery alone to aggressive cancers. Making a distinction between an indolent and a malignant GIST is unreliable with conventional histopathological techniques. The presence of metastases at the time of diagnosis confirms malignancy, but all GISTs should be regarded as having malignant potential. GISTs characteristically express the KIT protein, a transmembrane tyrosine kinase receptor for stem-cell factor. Most GISTs have a mutation in the KIT proto-oncogene that translates into a gain-of-function constitutive activation of the KIT kinase. KIT activation seems to be an early tumour-promoting event in pathogenesis. Commonly, malignant GISTs show high-level primary resistance to conventional chemotherapy. Imatinib mesylate is an orally administered selective inhibitor of certain tyrosine kinases including KIT. Most patients with advanced malignant GISTs achieve clinical benefit and significant antitumour responses with imatinib mesylate. Responses have been durable, and most patients tolerate the drug well at clinically effective doses. Imatinib mesylate is the first effective systemic therapy for advanced GIST.

Multiple small intestinal stromal tumours in a patient with previously unrecognised neurofibromatosis type 1: immunohistochemical and ultrastructural evaluation

Neurofibromatosis type 1 could be associated with multiple gastrointestinal stromal tumours, although their presence is not considered among the major diagnostic criteria. We present here a case of a 50-year-old female complaining of abdominal pain, with about 100 small intestinal stromal tumours. This finding prompted us to suspect a neurofibromatosis which was clinically confirmed afterwards. Light microscopy examination revealed a low-grade stromal tumour with skeinoid fibres. Mixed neural-interstitial cells of Cajal origin or, alternatively, neural differentiation of interstitial cells of Cajal are discussed on the basis of immunophenotype (CD117+, CD34+) and ultrastructure. A 2-year follow-up did not indicate an aggressive course in the case of this neoplasm.

Familial multiple gastrointestinal stromal tumours with associated abnormalities of the myenteric plexus layer and skeinoid fibres

AIMS

Multiple familial gastrointestinal stromal tumours are rare. We report the third family with two cases of multiple gastrointestinal stromal tumours showing skeinoid fibres. Associated abnormalities of the myenteric plexus layer are described and new hypotheses for the histogenesis of gastrointestinal stromal tumours are formulated.

METHODS AND RESULTS

Multiple gastrointestinal stromal tumours developed in the duodenum and proximal jejunum were removed from mother and son. No history of a specific syndrome or of mastocytosis was known. Light microscopy revealed typical gastrointestinal stromal tumours with skeinoid fibres. An unusual abnormality of the myenteric plexus layer, showing a diffuse spindle cell hyperplasia, was noted in the macroscopically normal digestive wall. No abnormalities of the ganglion cells were associated. Tumours and the spindle cell hyperplasia showed similar morphological and immunohistochemical features with expression of CD34 and CD117 antigens. Follow-up revealed recurrences in the mother.

CONCLUSION

The morphological characteristics of these two cases of familial gastrointestinal stromal tumours and of the associated abnormalities of the myenteric plexus layer, help to better explain the histogenesis of multiple familial gastrointestinal stromal tumours. The hyperplasia of the myenteric plexus could be considered a risk factor for recurrent tumours.

Relationship between skeinoid fibers and stromal matrix in gastrointestinal stromal tumors: morphometric analysis with quick-freezing and deep-etching method

Our previous study of a gastrointestinal autonomic nerve tumor with skeinoid fibers (SF) using the quick-freezing and deep-etching method, suggested that the distance between one radix and a neighboring radix (DRNR) in pre-existing meshwork structures around the tumor cells is consistent with the periodicity of the SF. Therefore, measurement of the DRNR in the meshwork could clarify the significance of the pericellular matrix for SF development. In the present study, we analyzed the meshwork in three cases of gastrointestinal stromal tumor (GIST), which showed different immunohistochemical stainings, but confirmed to have smooth muscle differentiation (SMD) by immunohistochemistry and/or electron microscopy. The DRNR from the three cases of GIST showed similar histogram patterns (a peak of 20-30 nm, mean values of 28.02, 25.74 and 26.45 nm), which were significantly shorter than the periodicity of SF (a peak of 40-45 nm, mean value of 42.14). Although we need further studies with additional GIST cases, we speculate that the pericellular matrix of GIST with SMD is not suitable for SF development.

Structural variations of collagen in normal and pathological tissues: role of electron microscopy

The spectrum of ultrastructural appearances assumed by collagen in normal and pathological tissues is illustrated using techniques of thin section transmission electron microscopy and computer-assisted analysis. The normal fibrillar collagen types are described in order to provide a basis for comparing other normal and abnormal forms. In normal tissues, the anchoring fibril and basal lamina (basement membrane) represent tissue structures largely containing collagen but differing significantly in organisation from normal types I to III fibrillar collagen. In pathological tissue, deviations from normal fine structure are reflected in abnormal aggregates of collagen fibrils (amianthoid and skeinoid fibres) and abnormalities in fibril diameter and cross-sectional profile. Fibrous and segment long-spacing collagen represent two further organisational variants of collagen, the former found widely in pathological tissues, the latter very rarely. Much remains to be discovered about these abnormal collagen variants-their mode of formation, the cells that produce them, and their roles. They also present a challenge for the collagen biologist formulating hypotheses of collagen fibril assembly and molecular organisation.

Congenital gastrointestinal pacemaker cell tumor

The interstitial cells of Cajal complex within the gut wall function as a pacemaker to direct peristalsis. Their neoplastic counterpart is the gastrointestinal pacemaker cell tumor, a spindle and/or epithelioid cell mesenchymal tumor previously known as gastrointestinal stromal tumor or incorrectly called leiomyosarcoma in some cases of older reports. Although numerous cases of gastrointestinal leiomyosarcomas have been documented in the English-language literature, no pediatric case of gastrointestinal stromal tumor or gastrointestinal pacemaker cell tumor has, to our knowledge, been recorded. Herein, we report a case of congenital gastrointestinal pacemaker cell tumor confirmed by immunohistochemistry and electron microscopy in a full-term male newborn.

Type VI collagen immunoreactivity in skeinoid fibers in small intestinal stromal tumors

By immunoperoxidase analysis for types I to VI collagen, elastin, cytoskeletal components and some glycoproteins, we found type VI collagen immunoreactivity in amorphous eosinophilic deposits (skeinoid fibers) in three small intestinal stromal tumors. Negative results were obtained for types I, II, III, IV and V collagen, elastin, laminin, ubiquitin, intracellular filaments such as actin, desmin, vimentin, calponin and caldesmon, and glycoprotein such as lysozyme, factor XIIIa, beta2-microglobulin, alpha1-antitrypsin and alpha1-antichymotrypsin. In two lesions, the periodic acid-Schiff-positive skeinoid fibers were also focally labeled for amyloid P component.

Plexiform neurofibroma of the small bowel infiltrated with metastatic adenocarcinoma

Neurofibromatosis Type 1 (NF1) is not classically associated with gastrointestinal manifestations although these patients are at increased risk of several GI complications. We describe the ultrasound, CT and barium findings in a patient with NF1 who had a huge benign plexiform neurofibroma of the ileum that was infiltrated with metastatic adenocarcinoma.

Numerous eosinophilic globules (skeinoid fibers) in a duodenal stromal tumor: an exceptional case showing smooth muscle differentiation

A unique case of duodenal stromal tumor in a 51-year-old man is reported. The tumor histologically showed spindle cell proliferation and numerous eosinophilic globules. Most globules were composed of tangled 45 nm thick fibrils, which were ultrastructurally identical to 'skeinoid fibers'. The presence of glycogen granules in the tumor cells and the immunoreactivity for alpha-smooth muscle actin suggested smooth muscle differentiation. Focal ultrastructural findings also supported the smooth muscle nature of this tumor. There were no immunohistochemical and ultrastructural features indicating neural differentiation. In previous studies, the presence of such 'skeinoid fibers' was suggested to be a histological marker for neural differentiation in gastrointestinal stromal tumor. However, the findings in the present case suggest that numerous 'skeinoid fibers' can be identified in duodenal stromal tumor with smooth muscle differentiation, although this condition may be rare.

Jejunal stromal tumor with skeinoid fibers or myenteric plexoma: a case report

Small intestinal stromal tumors with 'skeinoid fibers' are uncommon stromal tumors with an associated controversial histogenesis. Although their microscopic appearance is suggestive of a smooth muscle nature, they lack specific smooth muscle features, as evident by electron microscopy and immunohistochemistry. They also appear to lack features of neurogenic origin because they fall to react with neural/neuroendocrine markers such as S-100 protein, neuron-specific enolase and chromogranin. It is interesting, nonetheless, to note that the ultrastructural examination of these tumors may show structures reminiscent of neural differentiation, such as cytoplasmic projections, containing occasional membrane-bound, dense-core, neurosecretory-type granules, which mimick the long cytoplasmic processes seen in tumors of neural origin. Moreover, the association of these tumors with Von Recklinghausen's neurofibromatosis, as well as the presence of 'skeinoid fibers' in proven neurogenic spindle cell neoplasms such as gastrointestinal autonomic nerve tumors and schwannomas, suggests that these tumors might also be neurogenic in origin and enhances the diagnostic value of 'skeinoid fibers' as a possible ultrastructural marker of neural differentiation. Thus, light microscopic evaluation is clearly insufficient to accurately diagnose these tumors and to determine their histogenesis, electron microscopic and immunohistochemical studies being necessary. In this article the histogenesis of small intestinal stromal tumors with 'skeinoid fibers', regarding a jejunal neoplasm in a 63-year-old patient, is reviewed. The light microscopic, immunohistochemical and ultrastructural features are described and compared with findings usually seen in all those stromal tumors which may raise a differential diagnosis, such as smooth muscle stromal tumors, gastrointestinal autonomic nerve tumors, schwannomas, paragangliomas and fibrosarcomas.