胃肠间质瘤CT和MRI表现及漏误诊分析

目的：探讨胃肠间质瘤CT和MRI表现、分析漏诊和误诊的原因。方法回顾性分析20例经病理证实的胃肠道间质瘤CT和MRI表现,15例行CT检查,5例行MRI检查。结果单发19例(发生于胃12例,小肠4例,直肠1例,肠系膜2例);多发1例(发生于乙状结肠系膜和空肠)。表现为圆形或类圆形肿物,边界清晰,向腔外、腔内或跨壁生长的肿物,长径约2-10cm。CT平扫密度不均匀,多有坏死、囊变,可见Torri-celli-Bernoulli征;T1WI为不均匀低信号,T2WI为不均匀高信号,DWI为高信号。增强扫描肿物实性部分不均匀明显延迟强化。漏诊2例,均位于充盈不佳的胃体部。误诊3例,2例误诊为囊腺癌;1例误诊为直肠癌。结论胃肠间质瘤发生部位多变,充分的肠道准备和掌握其CT和MRI的表现,有助于避免漏诊和误诊。     

Urethral stromal tumor with pacemaker cell phenotype

Penile malignancies are rare in developed countries. The authors present a case of a penile urethral mesenchymal tumor occurring in a 51-year-old Caucasian male and displaying light microscopic, immunohistochemical, and ultrastructural features suggestive of a pacemaker cell type, combined with a lack of diagnostic features of any other established tumor category. The immunohistochemical profile was intensely positive for vimentin, PKC θ, and NSE and weakly positive to nonreactive for CD34 and smooth muscle actin, and entirely negative for CD117 (c-kit), S-100, and other markers. C-kit and PDGFRA gene analysis showed no mutations. Electron microscopy revealed tumor cells with plentiful cytoplasm and cytoplasmic processes/filopodia, both filled with intermediate filaments and occasional solitary focal densities. There were also prominent smooth endoplasmic reticulum cisternae, caveolae, neurosecretory granules, particularly concentrated in cytoplasmic processes, and synaptic-type structures. Poorly formed basal lamina, gap junctions, and intercellular collagen aggregates, consistent with skeinoid-type fibers, were also noted. Interstitial cells with potential pacemaker function have been recently described in the lower urinary tract, including the urethra, and this tumor may be related to this cellular phenotype.     

An oncogenetic tree model in gastrointestinal stromal tumours (GISTs) identifies different pathways of cytogenetic evolution with prognostic implications

To model the cytogenetic evolution in gastrointestinal stromal tumour (GIST), an oncogenetic tree model was reconstructed using comparative genomic hybridization data from 203 primary GISTs (116 gastric and 87 intestinal GISTs, including 151 newly analysed cases), with follow-up available in 173 cases (mean 40 months; maximum 133 months). The oncogenetic tree model identified three major cytogenetic pathways: one initiated by -14q, one by -1p, and another by -22q. The -14q pathway mainly characterized gastric tumours with predominantly stable karyotypes and more favourable clinical course. On the other hand, the -1p pathway was more characteristic of intestinal GISTs, with an increased capacity for cytogenetic complexity and more aggressive clinical course. Loss of 22q, more closely associated with -1p than -14q, appeared to initiate the critical transition to an unfavourable cytogenetic subpathway. This -22q pathway included accumulation of +8q, -9p, and -9q, which could all predict disease-free survival in addition to tumour site. Thus, insights into the cytogenetic evolution obtained from oncogenetic tree models may eventually help to gain a better understanding of the heterogeneous site-dependent biological behaviour of GISTs.     

COVID-19 in patients with gastrointestinal stromal tumors: Recommendations for management and vaccination

The coronavirus disease 2019 (COVID-19) pandemic profoundly affected the management and treatment of patients with malignancies. Based on the progress reported in the literature, we reviewed the recommendations for treatment and vaccination in patients with gastrointestinal stromal tumor (GIST) during COVID-19. We focus on whether there is a risk and what could be the possible effects of vaccinating patients with GIST/cancer. Since the situation is quickly changing, and the health services have been severely disrupted, the diagnosis, treatment and recommendations for vaccination of these patients against COVID-19 are still not updated. The approval of vaccines in the pandemic gave hope that we would soon be able to return to a more normal life. However, the oncology community needs to adapt and provide the most effective treatment and care models for patients with rare cancer, such as GIST. Collecting data on the impact of vaccination in patients with GIST/cancer also will be beneficial in expanding knowledge about the future planning of treatment strategies and optimizing care in the event of a subsequent pandemic.     

Complete pathological response to Imatinib mesylate in an extraintestinal gastrointestinal stromal tumor

INTRODUCTION

Gastrointestinal stromal tumors (GIST) are the most frequent mesenchymal tumors of the digestive tract. Extraintestinal locations (EGIST) have been described showing similar pattern of immunohistochemical markers than GIST. Inhibitors of tyrosine kinases such as Imatinib or Sunitinib are the mainstay treatment in the management of advanced or metastatic GIST. Complete pathological response to these agents is an extremely rare event, especially in the case of EGIST due to its more aggressive behavior reported.

PRESENTATION OF CASE

Here we describe the case of a 61 years old woman, with an advanced GIST, who was operated after 10 months of Imatinib mesylate. The biopsy demonstrated the extra intestinal location of the tumor and a complete pathological response was confirmed.

DISCUSSION

Complete pathological response to Imatinib is a rare event. To our knowledge, this is the first report of complete response in an EGIST. New clinical, radiological and metabolic criteria of tumoral response to neoadjuvant treatment are revised.

CONCLUSION

EGIST complete pathological response to Imatinib can be achieved. However, recommendation of systematic neoadjuvant therapy with Imatinib remains investigational and more studies are warranted in the future.     

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).     

Gastrointestinal stromal tumors with exon 8 c-kit gene mutation might occur at extragastric sites and have metastasis-prone nature

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the human gut. Most sporadic GISTs have somatic gain-of-function mutations of the c-kit gene. The mutations are frequently found at exon 11, sometimes at exon 9 and rarely at exon 13 or 17. Recently, exon 8 c-kit gene mutations were reported in very minor proportion of sporadic GISTs. We also found 3 GISTs with exon 8 c-kit gene mutations in approximately 1,000 sporadic GISTs examined. In the present report, we showed the clinicopathological data of those GISTs. One case had a deletion of codon 419 of aspartate, and 2 cases had a substitution of 3 amino acids of codon 417 to codon 419 to tyrosine. The former was the same mutation recently reported in 2 GIST cases, but the latter has not been reported in any GISTs. All three cases occurred at extragastric sites and two of three showed distant metastasis. Since the remaining case was regarded as high risk for recurrence, imatinib adjuvant treatment has been done without evidence of metastasis. Our results confirmed the idea that exon 8 mutations are minor but actually existing abnormalities in sporadic GISTs, and suggested that such GISTs have a feature of extragastric development and a metastasis-prone nature. Since the exon 8 mutations appeared to be really sensitive to imatinib as shown in the present case study, accurate genotyping including exon 8 of the c-kit gene is necessary in GISTs to predict response to imatinib in both the unresectable/metastatic and adjuvant settings.