Fibromixoma plexiforme del antro gástrico: descripción de 2 casos y revisión de la literatura / Plexiform fibromyxoma of the gastric antrum: a report of 2 cases and a review of the literature

El tumor miofibroblástico angiomixoide plexiforme o fibromixoma plexiforme es una neoplasia mesenquimal benigna, rara, recientemente descrita, que afecta al antro gástrico. Histológicamente presenta crecimiento plexiforme y está compuesta por células fibro/miofibroblásticas en un estroma mixoide, variable, con marcada trama capilar. En el presente artículo llevamos a cabo una revisión de la literatura y aportamos 2 casos adicionales en pacientes jóvenes (36 y 46 años) que consultaron por molestias gástricas inespecíficas y hemorragia digestiva alta. Ambas lesiones estaban situadas en la submucosa y en la capa muscular propia y presentaban un patrón de crecimiento plexiforme. Las células tumorales eran fusiformes y se disponían en el seno de una matriz mixoide abundante. La vascularización estaba constituida por numerosos vasos de pared fina y pequeño calibre. Con las técnicas de inmunohistoquímica, las células tumorales fueron positivas para actina de músculo liso, vimentina, caldesmón y desmina (un caso) y negativas para CD117, DOG1, EMA, S100, Beta-catenina y CD34. El estudio molecular no detectó mutaciones en los genes KIT y PDGFRA, en ninguno de los 2 casos. Hasta la fecha (4 años y 8 meses), ninguno de los pacientes ha desarrollado recidivas ni metástasis. El diagnóstico diferencial incluye una gran variedad de lesiones mixoides que pueden asentar o invadir la pared del estómago (GIST, tumor desmoide intraabdominal, pólipo fibroide inflamatorio, leiomioma-leiomiosarcoma, perineuroma, schwannoma y neurofibroma), pero solo el neurofibroma plexiforme comparte su característico patrón de crecimiento. Aunque en la revisión de la literatura hemos encontrado un total de 23 casos bajo la denominación de tumor gástrico miofibroblástico angiomixoide plexiforme o fibromixoma plexiforme, también hemos advertido que antes de la introducción de estos términos se habían descrito lesiones gástricas mixoides semejantes, no muy bien caracterizadas, que comparten mayoritariamente la localización antral gástrica, por lo que cabría especular sobre la posible existencia de una misma entidad con variable grado de diferenciación fibro/miofibroblástica y de patrón plexiforme, desarrollada probablemente en una población celular limitada exclusivamente al estómago(AU)

Plexiform, angiomyxoid myofibrobastic tumour, or plexiform fibromyoma, is a rare, recently described, benign neoplasm that affects the gastric antrum. Histologically the tumour has a plexiform growth pattern and is composed of fibro/myofibroblastic cells in a variable mixed stroma with a prominent capillary network. We have reviewed the literature and present 2 further cases occurring in young patients (36 and 46 years of age) who presented with gastric discomfort and upper gastrointestinal bleeding. Both lesions were located in the submucosa and muscularis and showed a plexiform growth pattern. Fusiform cells were found in an abundant myxoid extracellular matrix. Numerous small fine-walled blood vessels were present. Immunohistochemistry revealed positivity for smooth muscle actin, vimentin, h-caldesmon and desmin (in one case) and negativity for CD117, DOG1, EMA, S100, Beta-catenin and CD34. Molecular studies showed no mutations in the KIT and PDGFRA genes in either case. To date, neither of the patients has recurrences or metastases, 4 years and 8 months after diagnosis. Differential diagnosis includes a wide variety of myxoid lesions that may arise in or invade the stomach wall (GIST, intraabdominal desmoid tumour, inflammatory fibroid polyp, leiomyoma-leiomyosarcoma, perineuroma, schwannoma and neurofibroma), among these, plexiform neurofibroma is the only one showing the characteristic growth pattern. In our review of the literature, we found 23 cases described as gastric plexiform angiomyxoid myofibroblastic tumour, or gastric plexiform fibromyxoma. However, before the introduction of these terms, similar, if not completely characterized, gastric myxoid lesions had been described in the gastric antrum, suggesting that a single entity with a variable degree of fibro/myofibroblastic differentiation and a plexiform growth pattern might exist, perhaps developing in cells found only in the stomach(AU)

Umbilical cord stricture is not a genetic anomaly: a study in twins.

Two recent reports on recurrent cases of umbilical cord stricture (UCS) have opened the debate on the possibility of a genetic basis for this anomaly, traditionally considered to be sporadic. We present a series of 130 cases of UCS located at the fetal insertion, diagnosed among 2067 fetal and infantile autopsies performed during the last 10 years. All cases were macerated stillborn fetuses, and 54.6% were < or =20 weeks of gestational age. Our study is focused on 2 recurrent episodes and 16 cases occurring in multiple pregnancies. Among twins, males were affected more than females (2.2:1), although no statistical significance was found. Associated umbilical cord anomalies were present in 8 of 16 cases, consisting of hypocoiling (3 cases), hypercoiling (2 cases), excessive length (1 case), vascular tortuosity (1 case), and single umbilical artery (1 case). The most frequent placental finding was obliterative endovasculopathy (6 cases), probably indicating a causal relationship with UCS. Zygosity was analyzed by placental histology and/or a panel of 12 microsatellite markers to classify twins as monozygotic (8 cases) or dizygotic (8 cases). Our data prove that UCS is not a genetic condition because all 8 genetically identical twins were discordant for the anomaly and 2 dizygotic twins with UCS had co-twins also affected. Genetic factors are not implicated in UCS pathophysiology, and parents with a fetal demise due to UCS should be counseled as having a low-recurrence risk for subsequent pregnancies. Because there is not a higher incidence of UCS in multiple gestations, twinning should not be considered a risk factor for UCS.