Plexiform angiomyxoid myofibroblastic tumor of the stomach

GLI1, CDK4, and MDM2 Co-Amplification Gastric Plexiform Fibromyxoma: A Case Report and Literature Review

Plexiform fibromyxoma (PF) is a rare mesenchymal tumor that primarily occurs in gastric origin with a benign behavior. PF commonly harbors the MALAT1::GLI1 fusion gene. Here, we describe a case of a 36-year-old female with a PF. Abdominal computed tomography (CT) showed a 3.3 cm mass in the stomach. She underwent laparoscopic partial gastrectomy. Immunohistochemistry (IHC) of the tumor revealed strongly positive staining for CD34, SDHB, STAT6, MDM2, and CDK4. And the tumor showed TP53 mutant expression. Next-generation sequencing (NGS) comprehensive genomic profiling identified GLI1, CDK4, and MDM2 co-amplification and TP53 mutations. Here, we first report a case of a young woman with a PF harboring co-amplification of GLI1, CDK4, and MDM2 genes. The patient underwent complete removal of the tumor without the use of radiotherapy or chemotherapy. No recurrence was observed during the follow-up period of 8 months. This study aims to improve our understanding of PF by analyzing the clinicopathological characteristics of this case, including immunohistochemical (IHC) and genetic examination, and reviewing relevant literature.

Plexiform Fibromyxoma in the Stomach: Immunohistochemical Profile and Comprehensive Genetic Characterization

Plexiform fibromyxoma (PF), also referred to as plexiform angiomyxoid myofibroblast tumor, is an exceedingly rare mesenchymal neoplasm primarily affecting the stomach. Herein, we present a case of PF diagnosed in a 71-year-old male with a history of lung cancer, initially suspected to have a gastrointestinal stromal tumor (GIST) of the stomach, who subsequently underwent subtotal gastrectomy. The histopathological and molecular features of the tumor, including mutations in ABL1, CCND1, CSF1R, FGFR4, KDR, and MALAT1-GLI1 fusion, are elucidated and discussed in the context of diagnostic, prognostic, and therapeutic considerations.

Pediatric Plexiform Fibromyxoma: A Case Report

The plexiform fibromyxoma is a rare mesenchymal tumor in adults that generally originates in the antrum of stomach, being its occurrence in pediatric patients exceptional. It was classified as a distinct entity by World Health Organization in 2010. No recurrences and metastases have been documented in many of the reported patients to date, being the surgical treatment curative. We report the case of a 3-month-old infant who presented to the emergency department with an episode of intestinal subocclusion requiring an emergent surgery. During the surgical intervention, a mass was identified in the jejunum, causing partial occlusion of its lumen. The surgical pathology report revealed an infiltrative tumor composed of spindle-shaped cells disposed in a stroma with a plexiform pattern alternating myxoid areas. These findings and the immunohistochemical characteristics of the neoplastic cells led to classify the tumor as a plexiform fibromyxoma. A description of the immunophenotype of this tumor is made and differential diagnosis with other gastrointestinal tumors is also discussed.

A case of asymptomatic gastric plexiform fibromyxoma followed up for 3 years

Plexiform fibromyxoma is a rare mesenchymal tumor identified in recent years and presents as a gastrointestinal submucosal tumor that is typically located in the gastric antrum. We report a case of gastric plexiform fibromyxoma in which the diagnosis was difficult despite repeated tissue sampling. Before visiting our hospital, the patient had been followed up for 3 years without a definitive diagnosis despite serial examinations, including computed tomography, endoscopy, endoscopic ultrasound, and endoscopic ultrasound-guided fine-needle aspiration. Endoscopic ultrasound-guided fine-needle aspiration was reperformed, and endoscopic submucosal dissection for deep biopsy was conducted for differential diagnosis of the tumor. However, histological analysis with immunostaining of tumor samples obtained using these techniques cannot provide a reliable diagnosis. Finally, the tumor was resected surgically because of its increasing size, and subsequent microscopic analysis revealed a multinodular plexiform growth pattern of spindle-like cells with myxoid stroma. Immunohistochemically, the tumor cells were positive for smooth muscle actin but negative for c-kit, CD34, and S100. Based on these findings, the patient was diagnosed with plexiform fibromyxoma. No evidence of residual or recurrent tumors was observed at 24 months postoperatively.

Endoscopic submucosal excavation for gastric plexiform fibromyxoma: A case report and systematic review of literature

Plexiform fibromyxoma (PF) is a rare mesenchymal tumor of which the pathogenesis and molecular changes are still unclear. Histologically, it is characterized by a cluster of bland spindle or ovoid cells growing in the mucoid or fibromyxoid stroma rich in small blood vessels. At present, surgical resection is the primary treatment for PF.

Plexiform angiomyxoid myofibroblastic tumor treated by endoscopic submucosal dissection: A case report and review of the literature

BACKGROUND

Plexiform angiomyxoid myofibroblastic tumor (PAMT) is a rare mesenchymal tumor characterized by multiple nodular plexiform growth patterns and an immunophenotype with myofibroblasts. The pathological characteristics, immunohistochemistry, diagnostic criteria, differential diagnosis, and gene-level changes of PAMT have been reported in many studies. At present, the main treatment for PAMT in the reported cases is surgery; only eight cases were treated via endoscopy (excluding 1 thoracoscopic resection), and the lesions were all smaller than 5 cm. There are no reports on the prognosis and follow-up of young patients with lesion sizes reaching 5 cm who undergo endoscopic submucosal dissection (ESD). Herein, we present the first case of a young patient with a lesion size reaching 5 cm who was diagnosed with PAMT via endoscopic submucosal dissection.

CASE SUMMARY

A 15-year-old young man with upper abdominal pain for 2 years presented to the Gastroenterology Department of our hospital. Painless gastroscopy showed a semicircular bulge approximately 5 cm in size in the lesser curvature near the cardia of the fundus; the surface was eroded, and shallow ulcers had formed. The pathological manifestations of the biopsy were spindle cell proliferative lesions with interstitial mucinous changes, and the surface mucosa showed chronic inflammatory changes with active lesions; immunohistochemistry showed smooth muscle actin (SMA) (+), CD117 (-), CD34 (-), DOG-1 (-), S-100 (-), and Ki67 (LI: < 1%). We performed ESD on the patient. The lesion that we removed was 5 cm × 4 cm × 2 cm in size. Pathologically, the resected tissue displayed typical manifestations, such as fat spindle-shaped fibroblasts and myofibroblast-like cells showing irregular nodular hyperplasia. Immunohistochemistry staining of the tumor cells revealed the following: CD34 (partially +), SMA (weakly +), CD117 (-), DOG-1 (-), S-100 (-), SDHB (+), PCK (-), and Ki67 (labelling index: 2%). There was no recurrence or metastasis during the 3-mo follow-up after the operation, and the treatment effect was good. We also performed a review of the literature on the clinical manifestations, pathological features, immunohistochemistry, and differential diagnosis of PAMT.

CONCLUSION

At present, the diagnostic criteria for PAMT are relatively clear, but the pathogenesis and genetic changes require further study. PAMT is benign in nature, and these patients are less likely to experience local or metastatic recurrence. The main treatment is still surgery if the lesion is in the stomach. Partial gastrectomy and distal gastrectomy are the most frequently performed surgical treatments for PAMT, followed by local resection, subtotal gastrectomy, and wedge resection. But for comprehensive evaluation of the disease, ESD can be considered a suitable method to avoid excessive treatment.

Plexiform fibromyxoma: a clinicopathological and immunohistochemical analysis of two cases with a literature review

OBJECTIVE

This article aimed to study the clinicopathological features, immunophenotypes, and differential diagnoses of plexiform fibromyxoma (PF).

METHODS

We searched clinical and pathology databases of our hospital for patients with histologically confirmed PF from 2007 to 2020 and reviewed the relevant English and Chinese language literature.

RESULTS

Two cases of PF were identified, a 67-year-old woman and a 23-year-old man. Both patients presented with melena and anemia and underwent partial gastrectomy. Histologically, the tumors exhibited a plexiform growth pattern in the gastric submucosa and the presence of bland-looking spindle cells in the fibromyxoid stroma with the formation of small blood vessels. Immunohistochemically, the two cases were strongly positive for vimentin, smooth muscle actin, and muscle-specific actin and negative for CD117, discovered on gastrointestinal stromal tumors protein 1, CD34, CD10, S100, desmin, H-caldesmon, estrogen receptor, progesterone receptor, β-catenin, and cytokeratin.

CONCLUSIONS

PF is a rare mesenchymal tumor of the stomach that can be distinguished from other gastrointestinal mesenchymal tumors based on its distinctive morphology and immunophenotype.

Gastric plexiform fibromyxoma, an uncommon mesenchymal tumor

Plexiform fibromyxoma (PF) is an uncommon primary tumor of the gastrointestinal tract, with a mesenchymal origin and a benign behavior. Herein, we report a case and provide a literature review. A 41-year-old male patient underwent surgery in our unit for a PF at the gastric antrum, after being admitted due to vomiting and weight loss. As illustrated by our case, the mean age at presentation is around 40 years, the antrum is the most common location and abdominal pain the most widely reported manifestation. None of the reviewed cases involved regional or distant spread.

Plexiform fibromyxoma: Review of rare mesenchymal gastric neoplasm and its differential diagnosis

Plexiform fibromyxoma (PF) is a very rare mesenchymal neoplasm of the stomach that was first described in 2007 and was officially recognized as a subtype of gastric mesenchymal neoplasm by World Health Organization (WHO) in 2010. Histologically, PF is characterized by a plexiform growth of bland spindle to ovoid cells embedded in a myxoid stroma that is rich in small vessels. The lesion is usually paucicellular. While mucosal and vascular invasion have been documented, no metastasis or malignant transformation has been reported. Its pathogenesis is largely unknown and defining molecular alterations are not currently available. There are other mesenchymal tumors arising in the gastrointestinal tract that need to be differentiated from PF given their differing biologic behaviors and malignant potential. Histologic mimics with spindle cells include gastrointestinal stromal tumor, smooth muscle tumor, and nerve sheath tumor. Histologic mimics with myxoid stroma include myxoma and aggressive angiomyxoma. Molecular alterations that have been described in a subset of PF may be seen in gastroblastoma and malignant epithelioid tumor with glioma-associated oncogene homologue 1 (GLI1) rearrangement. The recent increase in publications on PF reflects growing recognition of this entity with expansion of clinical and pathologic findings in these cases. Herein we provide a review of PF in comparison to other mesenchymal tumors with histologic and molecular resemblance to raise the awareness of this enigmatic neoplasm. Also, we highlight the challenges pathologists face when the sample is small, or such rare entity is encountered intraoperatively.

Calcifying fibrous tumor of the gastrointestinal tract: A clinicopathologic review and update

Calcifying fibrous tumor (CFT) is a rare mesenchymal lesion that has been documented throughout the gastrointestinal tract. Gastrointestinal CFTs may occur at virtually any age, with a predilection for adults and for females. They occur most commonly in the stomach and the small and large intestines. CFTs are most often found incidentally, cured by local resection, and have a low risk of recurrence. Histology shows three characteristic features: Spindle cell proliferations within a densely hyalinized stroma, scattered calcifications, and lymphoplasmacytic inflammation. CFTs are immunoreactive for CD34, vimentin and factor XIIIa, helping to distinguish them from other benign mesenchymal neoplasms. The differential diagnosis of CFTs includes sclerosing gastrointestinal stromal tumor, leiomyoma, schwannoma, solitary fibrous tumor, inflammatory myofibroblastic tumor, plexiform fibromyxoma, fibromatosis, sclerosing mesenteritis, and reactive nodular fibrous pseudotumor. The pathogenesis of CFTs remains unclear, but some have hypothesized that they may be linked to IgG4-related disease, inflammatory myofibroblastic lesions, hyaline vascular type Castleman disease, sclerosing angiomatoid nodular transformation of the spleen, or trauma.

Frequency of Plexiform Fibromyxoma relative to gastrointestinal stromal tumor: A single center study

Plexiform Fibromyxoma (PF) is an exceedingly rare mesenchymal tumor of the gastric antrum that was first described in 2007. PF is a close mimic of gastrointestinal stromal tumor (GIST) clinically and histopathologically, but the frequency of PF relative to GIST is unknown. Moreover, although likely benign, long-term follow-up of PF is limited due to its recent description and rarity. PF has not been reported in distal jejunum. 118 primary GISTs that were surgically resected at our center (2000-2019) were retrieved. The patients' age, gender, clinical presentation, tumor location, size and number, and the presence or absence of metastasis, were documented. Risk of progressive disease was assessed according to the published GIST risk stratification model. Two unique cases of PF were compared. One gastric PF has been followed-up for 8 years, and the other occurred in the distal jejunum. In the latter, the PF diagnosis was rendered after the case was re-reviewed for the study. Clinical presentation resembled GIST in both PF cases. 14% of GISTs showed high risk features or were clinically malignant, whereas the PF patient with 8-year follow-up was free of disease. Based on this study, PF may be under-recognized, with 1 to 2% (1.7%) of GIST-like tumors possibly representing PF. PF may involve variable segments of intestine similar to GIST. Given the remarkable clinical and histopathologic overlap with GIST but differing outcomes, awareness and cognizance of this rare entity, plexiform fibromyxoma, is required for proper patient care.

A rare case of plexiform fibromyxoma in stomach: FNA diagnosis with histological correlation and differential diagnoses

Plexiform angiomyxoma (PF) is a rare benign mesenchymal neoplasm that arises in the antrum and pyloric region of the stomach. To the best of our knowledge, there are only two prior endoscopic ultrasound guided fine needle aspiration cytology examples have been reported. We report a case of PF which was diagnosed via EUS FNA and later confirmed on resection specimen. Differential diagnoses of this tumor are discussed. Although diagnosis of plexiform fibromyxoma on FNA specimen is difficult, a good FNA specimen with subsequent careful morphological evaluation and immunohistochemical staining work-up makes this task possible.

Uninodular Fibromyxomatous Gastric Tumor Resected by Endoscopic Submucosal Dissection

Esophagogastroduodenoscopy of a 45-year-old woman revealed a submucosal tumor in the gastric antrum. Endoscopic submucosal dissection of the tumor was performed. The histological findings revealed a fibromyxomatous tumor composed of myofibroblastic cells with no evidence of malignancy. The growth pattern of the resected specimen was not multinodular or plexiform. We therefore tentatively referred to the present tumor descriptively as a gastric uninodular fibromyxomatous tumor, stressing its singular nodularity. It was initially roughly 10 mm in size but grew over a period of 4 years. A uninodular plexiform fibromyxoma might increase in size but might not become multinodular if it remains small.

An Update on Clinicopathological and Molecular Features of Plexiform Fibromyxoma

Plexiform fibromyxoma is a rare and newly described gastric mesenchymal tumor with only 121 reported cases in the literature. Our understanding of plexiform fibromyxoma requires updating since the first case has been reported by Takahashi et al. 12 years ago. The present review summarized reported cases in the literature, and both clinical and pathological aspects of plexiform fibromyxoma were comprehensively discussed. Plexiform fibromyxoma usually causes nonspecific or bleeding signs or symptoms, and therefore clinical recognition of the disease is challenging. Plexiform fibromyxoma is of benign nature without any metastasis or recurrence reported, and more conservative surgical treatment should be considered.

Pediatric plexiform fibromyxoma: A PRISMA-compliant systematic literature review

BACKGROUND

Plexiform fibromyxoma (PF) is a rare gastric mesenchymal tumor, with approximately 80 cases reported to date. Gastrointestinal stromal tumor, the most common primary mesenchymal tumor of the stomach, shows different biological and clinical characteristics between adult and pediatric patients.

OBJECTIVES

This systematic literature review was conducted to elucidate the pathological and clinical features of pediatric PF compared to adult PF.

METHODS

MEDLINE (1948 to March 2018) and EMBASE (1947 to March 2018) were searched, and all English articles that reported clinical data on PF patients were identified. Two authors independently reviewed the articles and extracted data to assess immunohistochemistry, sex, chief complaint, tumor size, tumor-related mortality, and tumor recurrence and metastasis.

RESULTS

A total of 41 reports with 80 PF patients (of whom 70 were adult PF and 10 were pediatric PF patients) confirmed by histological and immunohistochemical findings were included. Of a total of 80 tumors, 62 (78%) were located in the gastric antrum, 42 (65%) presented with ulceration, and 48 (74%) were resected by partial gastrectomy. Median tumor size of the resected specimen was larger in pediatric PF than in adult PF cases (5.3 cm vs 4.0 cm, P = .036). However, there was no difference between pediatric and adult PFs in immunohistochemical expression, sex predominance, chief complaint, tumor-related mortality, and tumor recurrence and metastasis during the follow-up periods.

CONCLUSION

Other than increased tumor growth in pediatric PFs, PF is a single disease entity with similar pathological features and benign clinical behavior regardless of onset age.

Plexiform fibromyxoma of the small bowel: A case report

BACKGROUND

Plexiform fibromyxoma is a rare, special type of mesenchymal tumor. The most common presenting symptoms are anemia, hematemesis, and hematochezia, without sex or age predilection. The reported cases have mainly occurred in the gastric antrum and pylorus region, with some cases in the duodenum.

CASE SUMMARY

We report here a case of plexiform fibromyxoma in the upper segment of the jejunum, which was continuously followed up for 3 years after surgical removal. Plexiform fibromyxoma showed multinodular or plexiform growth. The cells in the tumor node were spindle-shaped but few in number and mitotic figures. Small blood vessels and mucous matrix were found among the tumor cells. Immunohistochemistry revealed that the plexiform fibromyxoma cells were positive for smooth muscle actin, focally positive for CD10, and negative for cytokeratin, CD117, DOG-1 (discovered on GIST-1) desmin, S-100, epithelial membrane antigen, and CD34. Ki-67 labeling index was < 5%. Plexiform fibromyxoma showed benign biological behavior. After 3 years of consecutive postoperative follow-up, no obvious signs of metastasis or recurrence were found by imaging examination.

CONCLUSION

Plexiform fibromyxoma is a rare type of mesenchymal tumor. The diagnosis mainly depends on pathological examination, and it should be distinguished from other gastrointestinal mesenchymal tumors.

Endoscopic ultrasound FNA: An illustrated review of spindle cell neoplasms of the upper gastrointestinal tract including a novel case of gastric plexiform fibromyxoma

Plexiform fibromyxoma (PF) is a recently-described and rare mesenchymal neoplasm of the gastric wall. A few small case series reports of this spindle cell entity exist in the surgical pathology literature, but to our knowledge no prior endoscopic ultrasound guided fine needle aspiration cytology examples have been reported. In clinical practice, mural gastrointestinal (GI) lesions are often initially evaluated by endoscopic ultrasound guided (EUS) fine needle aspiration (FNA). In addition, newer EUS fine needle biopsy techniques also allow for reliable retrieval of core tissue samples with intact cellular architecture, making EUS histopathologic analyses possible. We report a combined EUS FNA and core biopsy case of PF and correlate the findings with imaging results. The cytomorphology of PF is described and illustrated, and important entities in the differential diagnosis of upper GI spindle cell lesions (including GI stromal tumor, leiomyoma, schwannoma, carcinoid tumor, desmoid-type fibromatosis, and inflammatory fibroid polyp) are reviewed. Illustrated examples of relevant cytomorphologic, cell block histomorphologic and immunohistochemical characteristics are emphasized.

Imaging findings of gastric plexiform fibromyxoma with a cystic change: A case report and review of literature

RATIONALE

Plexiform fibromyxoma (PF) is an extremely rare mesenchymal tumor of the stomach, and its radiological findings have not been well described. Here, we analyzed the imaging features of a case of PF. To our knowledge, this is a rare reported case with a remarkable cystic change in the imaging literature.

PATIENT CONCERNS

A previously healthy 50-year-old woman presented with a 1-day history of abdominal pain. Then, she underwent computed tomography (CT) and magnetic resonance imaging (MRI). A cystic-solid well-circumscribed extraluminal mass was located in the posterior wall of the gastric upper body. The solid portion appeared as heterogeneous attenuation/intensity with progressive enhancement while the cystic region had no enhancement.

DIAGNOSES

The potential for malignancy could not be excluded.

INTERVENTIONS

Laparoscopic partial gastric resection was performed.

OUTCOMES

Based on pathological findings, a diagnosis of PF was made. The patient was alive without any recurrence or metastasis of the tumor after 2 years of follow-up.

LESSONS

As far as we know, a gastric PF with a remarkable cystic change has never been reported. Additionally, the tumor exhibited a progressive enhancement pattern which is a characteristic radiographic feature in our case. Our report may help increase the awareness of this rare but important new disease entity.

Plexiform fibromyxoma of the stomach: a clinicopathological study of 10 cases

Plexiform fibromyxoma (PF) is a unique mesenchymal tumor of the stomach. The molecular characteristics of these tumors remain unclear. Here, we report 10 cases of PF with clinicopathological features and molecular features in detail. The patients ranged in age from 26 to 72 years (mean, 49 y) and most commonly presented with abdominal pain and distension, black stool, and anemia. Eight tumors were located at the antrum while two in the fundus of stomach. Histologically, tumor cells exhibited a plexiform growth pattern with multiple nodules in the muscularis propria of stomach wall and infiltrative borders. Immunohistochemically, all tumors were strongly positive for vimentin and smooth muscle actin (SMA), some were staining for CD10 (5/10), desmin (5/10), H-caldesmon (6/10) and progesterone receptor (PR, 6/10), however, CD34, S-100, Estrogen Receptor (ER), ALK, CD117 and DOG-1 were all negative in our cases. The glioma-associated oncogene homologue 1 (GLI1) gene translocation was detected in eight cases by FISH with three positive and five negative. Mutation analyses of C-KIT and platelet-derived growth factor receptor alpha (PDGFRA) genes were performed on five cases and all of which were wild-type for mutation. Our follow-up indicated that all of the patients made an uneventful recovery at 24 to 95 months after diagnosis. In summary, the distinctively histological features and immunohistochemical positivity of SMA, CD10 and PR can help differentiate PF from other gastrointestinal mesenchymal tumors. GLI1 gene translocation offers an additional molecular instrument for the diagnosis. The expression of PR and the existence of GLI1 gene translocation in PF highlights of our article.

Rarity among benign gastric tumors: Plexiform fibromyxoma - Report of two cases

Plexiform fibromyxoma is a very rare mesenchymal tumor of the stomach, found almost exclusively in the antrum/pylorus region. The most common presenting symptoms are anemia, hematemesis, nausea and unintentional weight loss, without sex or age predilection. We describe here two cases of plexiform fibromyxoma, involving a 16-year-old female and a 34-year-old male. Both patients underwent complete resection (R0) by distal gastrectomy and retrocolic gastrojejunostomy (according to Billroth 2); for both, the postoperative course was uneventful. Histology showed multiple intramural and subserosal nodules with characteristic plexiform growth, featuring bland spindle cells situated in an abundant myxoid stroma with low mitotic activity. Immunohistochemistry showed α-smooth muscle actin-positive spindle cells, focal positivity for CD10, and negative staining for KIT, DOG1, CD34, S100, β-catenin, STAT-6 and anaplastic lymphoma kinase. One of the cases showed focal positivity for h-caldesmon and desmin. Upon follow-up, no sign of disease was found. In the differential diagnosis of plexiform fibromyxoma, it is important to exclude the more common gastrointestinal stromal tumors as they have greater potential for aggressive behavior. Other lesions, like neuronal and vascular tumors, inflammatory fibroid polyps, abdominal desmoid-type fibromatosis, solitary fibrous tumors and smooth muscle tumors, must also be excluded.

Gastric plexiform fibromyxoma resected by endoscopic submucosal dissection after observation of chronological changes: A case report

A 66-year-old man was diagnosed with a gastric submucosal tumor. Endoscopic ultrasound (EUS) revealed an iso/hypoechoic mass in the third layer. No malignant cells were detected in a histological examination. Yearly follow-up endoscopy and EUS showed the slow growth of the tumor. Endoscopic submucosal dissection (ESD) was performed and a glistening tumor was resected. The lesion showed a multinodular plexiform growth pattern consisting of spindle cells with an abundant fibromyxoid stroma that was rich in small vessels. The tumor was diagnosed as plexiform fibromyxoma (PF) by immunohistochemistry. Although difficulties are associated with reaching a diagnosis preoperatively, chronological changes on EUS may contribute to the diagnosis of PF. ESD may also be useful in the diagnosis and treatment of PF.

Computed tomography and magnetic resonance imaging of a plexiform angiomyxoid myofibroblastic tumor: a case report

Background

Plexiform angiomyxoid myofibroblastic tumor (PAMT) is a very rare mesenchymal tumor of the stomach. Here we report a case of pathologically confirmed PAMT with an unique cyst formation.

Case presentation

A 55-year-old male with a 10-year history of a gastric subepithelial tumor underwent computed tomography (CT) and magnetic resonance imaging (MRI). Two cysts were observed in the tumor, and the cyst wall showed moderately high intensity on T2-weighted images compared with the gastric wall. On dynamic study, the cyst wall showed a gradual enhancement pattern, and prominent enhancement was observed in the delayed phase. Laparoscopic partial gastric resection was performed, and a pathological diagnosis of PAMT was rendered.

Conclusion

We present a rare case of gastric PAMT, which was uniquely presented as cysts. One of the cysts in the tumor had an epithelial wall lining, which had never been reported before in gastric mesenchymal tumor, in addition to partial glandular structure. We reviewed our case, focusing on radiologic-pathologic correlation, and suggested hypothesis of cyst formation. According to our findings, PAMT with cyst formation would be included of differential diagnosis of gastric subepithelial tumors.

Duodenal plexiform fibromyxoma as a cause of obscure upper gastrointestinal bleeding: A case report

RATIONALE

We are reporting the first-to our knowledge-case of duodenal Plexiform Fibromyxoma causing obscure upper gastrointestinal bleeding.

PATIENT CONCERNS

Plexiform fibromyxoma triggered recurrent upper gastrointestinal bleeding episodes in a 63-year-old man who remained undiagnosed, despite multiple hospitalizations, extensive diagnostic workups and surgical interventions (including gastrectomies), for almost 17 years.

DIAGNOSES-INTERVENTIONS

During hospitalization for the last bleeding episode, an upper gastrointestinal endoscopy revealed an intestinal hemorrhagic nodule. The lesion was deemed unresectable by endoscopic means. An abdominal computerized tomography disclosed no further lesions and surgery was decided. The lesion at operation was found near the edge of the duodenal stump and treated with pancreas-preserving duodenectomy (1st and 2nd portion).

OUTCOMES

Postoperative recovery was mainly uneventful and a 20-month follow-up finds the patient in good health with no need for blood transfusions.Plexiform fibromyxomas stand for a rare and widely unknown mesenchymal entity. Despite the fact that they closely resemble other gastrointestinal tumors, they distinctly vary in clinical management as well as the histopathology. Clinical awareness and further research are compulsory to elucidate its clinical course and prognosis.

Gastrointestinal stromal tumor with a PDGFRA mutation masquerading as gastric plexiform fibromyxoma: A comparative clinicopathological study of two cases

Gastric plexiform fibromyxoma (PF) is a rare mesenchymal tumor with a histologically distinctive multinodular pattern, dissimilar to conventional gastrointestinal stromal tumor (GIST). The current study presents one case of gastric PF, and one case of GIST with a platelet-derived growth factor receptor α (PDGFRA) mutation mimicking PF, and discusses their differential diagnoses. The two patients were a 51-year-old male with PF and a 47-year-old female with GIST, each of whom presented with an occupying lesion in the gastric antrum. Histologically, the two cases shared a rare and approximately unanimous morphological pattern of a prominent multinodular and plexiform figuration in the gastric wall, including mucoid matrix, short spindle cells and small caliber vascular elements, and areas of stromal tumor cells exhibited an epithelioid appearance. Immunohistochemistry revealed that the PF tumor cells were positive for smooth muscle actin (SMA), but negative for mast/stem cell growth factor receptor (KIT), GIST-1 (DOG1), cluster of differentiation (CD) 34, S-100, desmin and cytokeratin AE1/AE3. The case of GIST expressed KIT and DOG1, but was negative for SMA, CD34, S-100, desmin and AE1/AE3. In addition, the GIST case, which was observed to harbor a D842V mutation in exon 18 of PDGFRA, was demonstrated to be genetically distinct from PF. The cases presented in the current study were uncommon in that GIST exhibited a plexiform appearance that mimicked the histology of the rare PF tumor; therefore, GIST must be considered and discounted first when determining a differential diagnosis for a gastrointestinal mesenchymal neoplasm.

A rare case of plexiform angiomyxoid myofibroblastic tumor in the stomach which was diagnosed at the earliest stage in the literature

Plexiform angiomyxoid myofibroblastic tumor (PAMT) is a rare gastric mesenchymal entity with a peculiar plexiform pattern, bland spindle cells and myxoid stroma rich in arborizing blood vessels. Here we report a 44-year-old Chinese woman with PAMT. Initially she was admitted for removal of a gastric antral‘polyp’ found on a routine examination 5 months previously. Our gastroscopy showed a 0.8 × 0.8 cm polyp-like mass in the antrum which protruded into the lumen. Endoscopic submucosal dissection (ESD) was performed to remove this mass en bloc. The specimen was carefully examined by pathologists, and the correct diagnosis of PAMT was finally made. The tumor in this case depicted typical histopathological and immunohistochemical features of gastric PAMT. This PAMT was not only the smallest on endoscopic examination in the literature but also—unlike the already reported PAMTs—exhibited a focal hyperechogenic lesion on endoscopic ultrasonography (EUS). This information highlights its value on how to identify a PAMT at its early stage.

Laparoscopy endoscopy cooperative surgery for gastric plexiform fibromyxoma: a case report

Background

Gastric submucosal tumors are commonly treated by partial resection under laparoscopy. However, the surgical resection of gastric submucosal tumors sometimes causes deformation of the stomach, especially in the case of intraluminal tumors located near the pylorus or esophagogastric junction. Such deformations can result in impaired diet intake and reduced quality of life. Laparoscopic endoscopic cooperative surgery has been developed to overcome these problems. This is the first report to describe a case of gastric plexiform fibromyxoma, a rare gastric submucosal tumor, that was successfully resected by laparoscopic endoscopic cooperative surgery.

Case presentation

A 36-year-old Japanese woman presented with epigastric pain and anemia. Gastrointestinal endoscopy revealed a submucosal tumor in the gastric antrum. Because a definitive diagnosis could not be obtained and the tumor was located near the pylorus, we performed laparoscopic endoscopic cooperative surgery as diagnostic therapy. The postoperative course was favorable with no complications, such as delayed gastric emptying or outlet obstruction. The tumor was pathologically diagnosed as gastric plexiform fibromyxoma.

Conclusions

Laparoscopic endoscopic cooperative surgery is a useful approach for diagnostic therapy for rare submucosal tumors to avoid the deformation of the stomach, especially when the tumor is located near the pylorus.

Plexiform angiomyxoid myofibroblastic tumor of stomach: A rare case

Plexiform angiomyxoid myofibroblastic tumor (PAMT) is a rare benign mesenchymal tumor of stomach. Rarity of this kind of tumors and scarce review articles may cause underrecognition of this entity and pose a real diagnostic challenge to gastroenterologists, pathologists and surgeons when encountering such patients and differentiating PAMT from other gastric intramural tumors. We report a case of 28-year-old woman, who presented with epigastric pain after meals, iron-deficiency anaemia and weight loss. Upper gastrointestinal endoscopy revealed submucosal tumor-like elevated lesion in the anterior wall of the antrum with intact overlying mucosa. Endoscopic ultrasound showed a 3-cm hypoechoic homogenous mass, originating from the third layer of the gastric wall. Endoscopic ultrasound-guided fine needle aspiration was not informative. Endoscopic buttonhole biopsy was performed to obtain specimens. Following this, the unexpected prolapse of the tumor occurred into the lumen of the stomach, causing gastric outlet obstruction - the biopsy was obtained. Pathomorphological features suggested the diagnosis of PAMT. Gastric resection of the Billroth I type was performed. Diagnosis was confirmed by histological analysis of the surgical specimen.

Plexiform angiomyxoid myofibroblastic tumor of the stomach: A case report

Plexiform angiomyxoid myofibroblastic tumor (PAMT) is a rare mesenchymal tumor of the stomach. To date, about 40 cases of PAMT have been reported in the literature. This tumor is not specific in clinical manifestations and microscopically characterized by a plexiform growth pattern. Here, we report the case of an 11-year-old male patient who was diagnosed with PAMT. He had a complaint of right epigastric discomfort with episodic pain, gastroscopy displayed a submucosal bulge at the pylorus, and CT showed a mass in the right abdomen with uneven, delayed enhancement, and a partial gastrectomy revealed a tumor at the pylorus. Histologically, the tumor was multinodular and rich in blood vessels with thin wall; the interstitium had abundant myxomatous stroma; the tumor cells were spindle-shaped, star-shaped, or oval. Immunohistochemically, the tumor cells were positive for Calponin, Caldesmon, and SMA, but negative for CD34, ALK, S-100, desmin, CD117, and Dog-1. This patient was followed up for 12 months, and recurrence or metastasis was not observed. Diagn. Cytopathol. 2017;45:55-58. © 2016 Wiley Periodicals, Inc.

Unusual focal keratin expression in plexiform angiomyxoid myofibroblastic tumor: A case report and review of the literature

BACKGROUND

Plexiform angiomyxoid myofibroblastic tumor (PAMT), also known as plexiform fibromyxoma, is a rare distinctive benign intramural tumor, typical of gastric antrum, commonly causing mucosal ulceration with upper gastrointestinal bleeding and anemia, effectively treated by complete surgical resection usually accomplished by distal gastrectomy.

METHODS AND RESULTS

We herein report a 47-year-old man presenting with a syncopal episode, regurgitation and epigastric discomfort, bearing a gastric antral myxoid plexiform tumor positive for α-smooth muscle actin, vimentin and, partially, for caldesmon, desmin, and CD10; CD117, DOG1, CD34, S100, CAM5.2, CK20, CK7, EMA, p53, CDX2, chromogranin A, synaptophysin, anaplastic lymphoma kinase, Melan-A, and HMB-45 were all negative. All these features are typical of PAMT. Of note, focal positivity for AE1/AE3 and pan-CK KL1 was also present.

CONCLUSIONS

The finding of a focal keratin expression in PAMT contributes to enlarge the immunophenotypic spectrum of this tumor type and is relevant for avoiding presurgical misdiagnoses which could ultimately lead to inappropriate overtreatment of patients with PAMT.

Recurrent MALAT1-GLI1 oncogenic fusion and GLI1 up-regulation define a subset of plexiform fibromyxoma

Plexiform fibromyxomas are rare neoplasms, being officially recognized as a distinct entity among benign mesenchymal gastric tumours in the 2010 WHO Classification of Tumours of the Digestive System. Characteristically, these tumours have a multinodular/plexiform growth pattern, and histologically contain variably cellular areas of bland myofibroblastic-type spindle cells embedded in an abundant myxoid matrix, rich in capillary-type vessels. As yet, the molecular and/or genetic features of these tumours are unknown. Here we describe a recurrent translocation, t(11;12)(q11;q13), involving the long non-coding gene metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) and the gene glioma-associated oncogene homologue 1 (GLI1) in a subgroup of these tumours. The presence of the fusion transcript in our index case was confirmed using polymerase chain reaction (PCR) on genomic DNA, followed by Sanger sequencing. We showed that the truncated GLI1 protein is overexpressed and retains its capacity to transcriptionally activate its target genes. A specific FISH assay was developed to detect the novel MALAT1-GLI1 translocation in formalin-fixed, paraffin-embedded (FFPE) material. This resulted in the identification of two additional cases with this fusion and two cases with polysomy of the GLI1 gene. Finally, immunohistochemistry revealed that the GLI1 protein is exclusively overexpressed in those cases that harbour GLI1/12q13 genomic alterations. In conclusion, overexpression of GLI1 through a recurrent MALAT1-GLI1 translocation or GLI1 up-regulation delineates a pathogenically distinct subgroup of plexiform fibromyxomas with activation of the Sonic Hedgehog signalling pathway. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Plexiform fibromyxoma with cotyledon-like serosal growth: A case report of a rare gastric tumor and review of the literature

Plexiform fibromyxoma is a rare, benign mesenchymal neoplasm that predilects the gastric antrum and has potential for misdiagnosis as a gastrointestinal stromal tumor (GIST). The histology of the tumor is characterized by interwoven fascicular growth of cytologically bland spindled cells within a variably myxoid stroma. The current study reports the clinicopathological and immunohistochemical findings of a plexiform fibromyxoma resected from a 28-year-old Vietnamese female. The patient presented with acute, severe abdominal pain and worsening anemia. The initial fine-needle aspiration and needle core biopsy of the gastric antral mass led to an initial diagnosis of GIST. The subsequent distal partial gastrectomy revealed a 5.5-cm transmural antral mass that ulcerated the overlying mucosa and grew as variably elongated, myxoedematous, polypoid (cotyledon-like) excrescences from the serosal surface. Microscopically, the tumor demonstrated plexiform and multinodular growth of cytologically bland spindled cells proliferating in an abundant myxocollagenous stroma with a prominent capillary network. Tumor cells immunohistochemically expressed smooth muscle actin and CD10, but did not express CD117, Discovered on GIST-1 or nuclear β-catenin. Follow-up evaluation 23 months post surgery revealed no evidence of residual tumor. A review the cases of this rare entity reported in the English language literature is also provided.

Plexiform Angiomyxoid Myofibroblastic Tumor (PAMT) of Stomach with Synchronous Bilateral Cystic Ovarian Neoplasms, a Rare Case Presentation

Plexiform Angiomyxoid Myofibroblastic Tumor (PAMT) is a recently identified mesenchymal tumor of the stomach, which was first described in the year 2007 and was added in the 2010 WHO classification of tumors of the digestive system World J Gastroenterol 16(6): 2835-2840, 2010. It closely resembles with other gastric tumors but distinctly varies in clinical management as well as the histopathology. We had a 51 year, female patient, laborer by profession with low socio economic status, who had abdominal pain with vomiting since 6 months. She had similar complaints 3 years ago for which she was evaluated and presumed to have Carcinoma Stomach and underwent laparotomy which ended up only with Gastro- Jejunal anastomosis. She was admitted at our institution. Endoscopy revealed antral bulge with central area ulceration and biopsy was taken which was not confirmatory for malignancy. CT images showed heterogeneous mass with necrotic changes arising from the duodenum favored the diagnosis of perigastric neoplasm. PET CT was done, 8.4 × 5 × 6.1 cm exophytic mass in the pyloric region of stomach with solid and cystic components causing significant gastric outlet obstruction. She underwent exploratory laparotomy and complete excision of mass with achievement of R0 clearance. Histopathology was reported as Plexiform angiomyxoid myofibroblastic tumor (PAMT).

Plexiform angiomyxoid myofibroblastic tumour of the duodenum: a rare entity

Plexiform angiomyxoid myofibroblastic tumour (PAMT) has recently emerged as a new entity among gastrointestinal mesenchymal tumours. All of the 27 cases reported until now originated from the stomach. We report the first case of a duodenal PAMT arising from the first part of the duodenum in a 19-year-old woman presenting with upper abdominal pain and an abdominal lump.

Beyond the GIST: mesenchymal tumors of the stomach

Intramural gastric masses arise in the wall of the stomach (generally within the submucosa or muscularis propria), often with intact overlying mucosa. These tumors are typically mesenchymal in origin and have overlapping radiologic appearances. A combination of features such as location, attenuation, enhancement, and growth pattern may suggest one diagnosis over another. Gastrointestinal stromal tumors (GISTs) account for the majority of intramural tumors and can vary widely in appearance, from small intraluminal lesions to exophytic masses that protrude into the peritoneal cavity, commonly with areas of hemorrhage or necrosis. A well-circumscribed mass measuring -70 to -120 HU is a lipoma. Leiomyomas usually manifest as low-attenuation masses at the gastric cardia. Homogeneous attenuation is a noteworthy characteristic of schwannomas, particularly for larger lesions that might otherwise be mistaken for GISTs. A hypervascular mass in the antrum is a common manifestation of glomus tumors. Hemangiomas are also hypervascular but often manifest in childhood. Inflammatory fibroid polyps usually arise as a polypoid mass in the antrum. Inflammatory myofibroblastic tumors are infiltrative neoplasms with a propensity for local recurrence. Plexiform fibromyxomas are rare, usually antral tumors. Carcinoid tumors are epithelial in origin, but often submucosal in location, and therefore should be distinguished from other intramural lesions. Multiple carcinoid tumors are associated with hypergastrinemia, either in the setting of chronic atrophic gastritis or Zollinger-Ellison syndrome. Sporadic solitary carcinoid tumors not associated with hypergastrinemia have a higher rate of metastasis. Histopathologic analysis, including immunohistochemistry, is usually required for diagnosis of intramural masses.

Presence of smooth muscle cell differentiation in plexiform angiomyxoid myofibroblastic tumor of the stomach: a case report

Plexiform angiomyxoid myofibroblastic tumor (PAMT) is a recently described distinctive gastric mesenchymal entity with a peculiar plexiform pattern, bland spindle cells and a myxoid stroma rich in arborizing blood vessels. In this study, we report a new case of this rare gastric tumor with a subset of tumor cells derived from smooth muscle differentiation. A 32-year-old Chinese man was admitted with a gastric mass. He did not experience any discomfort, and gastroscopy showed an elevated mass in the anterior wall of the gastric antrum. Endoscopic ultrasound examination revealed a focal hypoechoic lesion protruding into the lumen. A partial gastrectomy was performed, and the patient made an uneventful recovery and remains well 3 years later. The tumor in this case depicted all the typical histopathologic and immunochemical features of gastric PAMT, except that a small subset of tumor cells was partially immunoreactive for desmin and H-caldesmon. Based on the findings of this case, we think that PAMT may contain tumor cells derived from smooth muscle differentiation, and therefore this tumor may be more than just purely myofibroblastic in nature.

Plexiform angiomyxoid myofibroblastic tumor (PAMT) of the stomach. A case report focusing on its characteristic growth pattern

Plexiform angiomyxoid myofibroblastic tumor (PAMT) is a rare mesenchymal tumor of the stomach. We report herein a case with CT findings, which illustrate the characteristic growth pattern of PAMT. A 27-year-old female patient visited our hospital because of epigastric pain and anemia. The CT scan showed a heterogeneous tumor in the gastric antrum, which was drastically enhanced with contrast medium, and consisted of a number of highly stained small nodules around the tumor rim. The resected tumor, 4.6 cm in size, was c-kit negative and SMA-positive by immunohistochemistry, and composed of bland spindle cells which were separated by abundant myxomatous stroma. The tumor showed plexiform growth in the entire stomach wall, with multiple nodules protruding outward within the serosa. The CT findings in this case reflect the characteristic PAMT growth pattern, and are distinct enough to differentiate it from gastrointestinal stromal tumor (GIST).

Plexiform fibromyxoma: report of two pediatric cases and review of the literature

Plexiform fibromyxoma is a distinctive mesenchymal neoplasm usually arising in the gastric antrum. We report 2 cases of this entity in pediatric patients, including the first case arising in the esophagus. The patients were a 16-year-old female who presented with chest pain and was found on computed tomographic scan to have a midesophageal mass at the level of the carina, and an 11-year-old female with a gastric mass. Both patients underwent surgical resection of their tumors, which histologically exhibited a plexiform growth pattern with multiple nodules in the muscularis propria and infiltrative borders. The nodules were composed of a rich myxoid stroma with bland uniform spindle cells, no mitoses or necrosis, and delicate blood vessels in the background. Immunohistochemical studies demonstrated that the tumor cells were immunoreactive with smooth muscle actin and not reactive with S-100, CD34, desmin, and c-kit (CD117). We report the first case of plexiform fibromyxoma originating in the esophagus, emphasize its occurrence in pediatric patients, and review the related literature.

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).

Plexiform fibromyxoma (plexiform angiomyxoid myofibroblastic tumor) of stomach: an unusual presentation as a fistulating abscess

Plexiform fibromyxoma (plexiform angiomyxoid myofibroblastic tumor) is a rare benign mesenchymal tumor of stomach. The plexiform growth of bland-looking spindly cells in a richly vascularized fibromyxoid stroma is distinctive. The described cases are solid tumors associated with ulceration, with the patients presenting with symptoms related to the ulcer or mass effect of the tumor. We report an unusual case presenting as a fistulating abscess. A 42-year-old woman presented with abdominal pain, fever, and elevated white cell count. Computed tomography scan revealed a 12-cm cavitating mass in the gastric antrum, with fistulation to the gastric lumen through an ulcer. Histologic examination showed transmural involvement of the stomach by plexiform islands of fibromyxoid tumor with interspersed delicate capillaries. There was a pseudocyst-like component. The unusual presentation therefore broadens the clinical and pathologic spectrum of this rare tumor type.

[Plexiform angiomyxoid myofibroblastic tumour of the stomach]

Recently the so-called plexiform angiomyxoid myofibroblastic tumors (PAMT) have emerged as a new entity of gastric soft tissue tumors and the light microscopic and immunohistological characteristics have now been well described. Until now PAMTs have not yet been reported in the German speaking literature. Worthy of note is that PAMTs can be diagnosed safely in sufficient biopsy material which enables adequate therapeutic steps to be initiated without delay, because PMATs although considered to be benign, can cause serious complications.

Plexiform angiomyxoid myofibroblastic tumor of the stomach: report of two cases and review of the literature

Plexiform angiomyxoid myofibroblastic tumor (PAMT) of the stomach is a recently recognized entity. Because of its rarity, only 22 cases have been reported in the English-language literature and most of these are single case reports. We report two cases of gastric PAMT. The tumor cells were bland and plexiform arranged in a myxoid stroma, which was positive for alcian blue. Immunohistochemically, the tumor cells were positive for smooth muscle actin, but negative for c-kit, CD34, desmin, S-100 protein, epithelial membrane antigen, neurofilament, and protein kinase C-theta. Mutation analyses for exon 9, 11, 13, and 17 of KIT genes and 12, 14, and 18 of the platelet-derived growth factor receptor alpha (PDGFRA) genes were performed and the tumors were wild-type for mutation.

Plexiform angiomyxoid myofibroblastic tumor of the stomach: a case report

Plexiform angiomyxoid myofibroblastic tumor (PAMT) is a recently described mesenchymal tumor of the stomach. We report the first case of PAMT in Korea. A 52-yr-old man underwent esophagogastroduodenoscopy due to dyspepsia for 2 yr. There was a submucosal mass with small mucosal ulceration in the gastric antrum. The tumor measured 3.5 × 2.3 cm in size and showed multinodular plexiform growth pattern of bland-looking spindle cells separated by an abundant myxoid or fibromyxoid matrix rich in small thin-walled blood vessels. The tumor cells were negative for CD117 (c-KIT), CD34 and S-100 protein, but diffusely positive for smooth muscle actin consistent with predominant myofibroblastic differentiation. The patient is doing well without recurrence or metastasis for 5 months after surgery. Although there have been limited follow-up data, PAMT is regarded as a benign gastric neoplasm with histological and immunohistochemical characteristics distinguished from gastrointestinal stromal tumor and other mesenchymal tumors of the stomach.