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

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 fibromyxoma: Case report and literature review

Plexiform fibromyxoma (PF) is a rare mesenchymal neoplasm which can be misdiagnosed as the gastrointestinal stromal tumor. This tumor almost formed a lobulated intramural/submucosal mass in the gastric antrum and prepyloric area. It was considered as a benign tumor that exhibited no recurrence, metastasis, or tumor-related mortality. In this study, we reported 2 cases of gastric PF. The first case was a PF patient coexisting with gastric adenocarcinoma. The second case occurred in the gastric upper body close to gastric fundus. They underwent distal gastrectomy and laparoscopic partial gastric resection, respectively. Both of them exhibited a plexiform growth pattern in the submucosa, muscularis propria, and subserosal adipose tissues. The nodules were composed of abundant myxoid or fibromyxoid matrix riching in small thin-walled blood vessels and bland-looking spindle cells. The first case partially showed staggered growth pattern of PF and adenocarcinoma. Immunohistochemically, the spindle cells were diffusely immunoreactive for SMA and vimentin, and focally immunoreactive for CD10. It was important to distinguish the PF from other spindle cell tumors involving the stomach.

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.

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.

Loss of the PTCH1 tumor suppressor defines a new subset of plexiform fibromyxoma

BACKGROUND

Plexiform fibromyxoma (PF) is a rare gastric tumor often confused with gastrointestinal stromal tumor. These so-called "benign" tumors often present with upper GI bleeding and gastric outlet obstruction. It was recently demonstrated that approximately one-third of PF have activation of the GLI1 oncogene, a transcription factor in the hedgehog (Hh) pathway, via a MALAT1-GLI1 fusion protein or GLI1 up-regulation. Despite this discovery, the biology of most PFs remains unknown.

METHODS

Next generation sequencing (NGS) was performed on formalin-fixed paraffin-embedded (FFPE) samples of PF specimens collected from three institutions (UCSD, NCI and OHSU). Fresh frozen tissue from one tumor was utilized for in vitro assays, including quantitative RT-PCR and cell viability assays following drug treatment.

RESULTS

Eight patients with PF were identified and 5 patients' tumors were analyzed by NGS. An index case had a mono-allelic PTCH1 deletion of exons 15-24 and a second case, identified in a validation cohort, also had a PTCH1 gene loss associated with a suspected long-range chromosome 9 deletion. Building on the role of Hh signaling in PF, PTCH1, a tumor suppressor protein, functions upstream of GLI1. Loss of PTCH1 induces GLI1 activation and downstream gene transcription. Utilizing fresh tissue from the index PF case, RT-qPCR analysis demonstrated expression of Hh pathway components, SMO and GLI1, as well as GLI1 transcriptional targets, CCND1 and HHIP. In turn, short-term in vitro treatment with a Hh pathway inhibitor, sonidegib, resulted in dose-dependent cell killing.

CONCLUSIONS

For the first time, we report a novel association between PTCH1 inactivation and the development of plexiform fibromyxoma. Hh pathway inhibition with SMO antagonists may represent a target to study for treating a subset of plexiform fibromyxomas.

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.

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: A Rare Gastric Tumor

Plexiform fibromyxoma is a rare and distinctive benign mesenchymal neoplasm that occurs in the gastric antrum. This tumor has a potential for misdiagnosis as gastrointestinal stromal tumor (GIST). It causes mucosa and vascular ulcerations without advancement of the tumor. Cytological bland spindle cells within a variably myxoid stroma characterize the histology of the tumor. We report the case of a 41-year-old African Tanzanian lady who presented with melena and recurrent anemia. Endoscopy and imaging studies revealed antral mass with initial suspicion of a GIST. However, immunohistochemically it turned to be a plexiform fibromyxoma. Follow-up evaluation 12 months after surgery revealed no evidence of recurrence or metastasis. This is a very uncommon tumor, which, to our knowledge, has been reported only once in Africa. The clinicians need to be aware of this rare occurrence to avoid misdiagnosis as GIST tumor.

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.

Gastroblastoma harbors a recurrent somatic MALAT1-GLI1 fusion gene

Gastroblastoma is a rare distinctive biphasic tumor of the stomach. The molecular biology of gastroblastoma has not been studied, and no affirmative diagnostic markers have been developed. We retrieved two gastroblastomas from the consultation practices of the authors and performed transcriptome sequencing on formalin-fixed paraffin-embedded tissue. Recurrent predicted fusion genes were validated at genomic and RNA levels. The presence of the fusion gene was confirmed on two additional paraffin-embedded cases of gastroblastoma. Control cases of histologic mimics (biphasic synovial sarcoma, leiomyoma, leiomyosarcoma, desmoid-type fibromatosis, EWSR1-FLI1-positive Ewing sarcoma, Wilms' tumor, gastrointestinal stromal tumor, plexiform fibromyxoma, Sonic hedgehog-type medulloblastomas, and normal gastric mucosa and muscularis propria were also analyzed. The gastroblastomas affected two males and two females aged 9-56 years. Transcriptome sequencing identified recurrent somatic MALAT1-GLI1 fusion genes, which were predicted to retain the key domains of GLI1. The MALAT1-GLI1 fusion gene was validated by break-apart and dual-fusion FISH and RT-PCR. The additional two gastroblastomas were also positive for the MALAT1-GLI1 fusion gene. None of the other control cases harbored MALAT1-GLI1. Overexpression of GLI1 in the cases of gastroblastomas was confirmed at RNA and protein levels. Pathway analysis revealed activation of the Sonic hedgehog pathway in gastroblastoma and gene expression profiling showed that gastroblastomas grouped together and were most similar to Sonic hedgehog-type medulloblastomas. In summary, we have identified an oncogenic MALAT1-GLI1 fusion gene in all cases of gastroblastoma that may serve as a diagnostic biomarker. The fusion gene is predicted to encode a protein that includes the zinc finger domains of GLI1 and results in overexpression of GLI1 protein and activation of the Sonic hedgehog pathway.

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.

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.

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.