Differential diagnosis of gastrointestinal leiomyoma versus gastrointestinal stromal tumor

Differential diagnosis of gastrointestinal stromal tumors versus leiomyomas by special stains

The objective of the study was to investigate whether special stains can differentiate gastrointestinal stromal tumors (GISTs) and gastrointestinal leiomyomas (GILs). In this retrospective study, 39 cases of GISTs (diameter, 0.2-8.8 cm) and 75 cases of GILs (diameter, 0.2-4.5 cm) were recruited, all biopsy specimens were obtained by endoscopic submucosal dissection (ESD) and endoscopic mucosal resection (EMR) excision, and the depth of excision included the whole mucosa, mucosal myometria, and most submucosa. GISTs and GILs were the most common types of mesenchymal tumors found anywhere along the gastrointestinal (GI) tract, from the esophagus to the rectum. GISTs were often associated with a higher risk of malignancy. In this study, the gender, age of onset, size and sites of the lesions, together with the number of mucosal or lamina propria lesions all have significant differences, nevertheless, there was no significant difference in cell morphology of GISTs and GILs tested by hematoxylin eosin (H&E) stain, and all showed low echo areas by EUS examination. In this retrospective study, the GISTs and GILs had been diagnosed by immunohistochemistry combined with clinical morphology. Subsequently, special stains including Masson's trichrome (MT) stain, Alcian blue periodic acid-Schiff (AB-PAS) stain (pH 2.5), Wright-Giemsa (W-G) stain and periodic acid-Schiff (PAS) combined with diastase periodic acid-Schiff (D-PAS) stains were also applied in the diagnosis, the retrospective study results showed that 92.3% GISTs were stained blue with MT stain, 97.3% GILs were stained red with MT stain (P < 0.01), almost all GISTs were PAS-negative (light purple), in contrast, all GILs were PAS-positive (rose red) (P < 0.01), all of these experiments set control using the blood vessels stained by MT and AB-PAS stains. Nevertheless, there was no significant difference between GISTs and GILs stained by W-G stain. These obvious and meaningful differential results were also confirmed in the detection of new GISTs and GILs cases using MT and AB-PAS stains. In conclusion, MT and AB-PAS stains could also identify GISTs and GILs cases, particularly, AB-PAS was more sensitive and more specific, providing a more cost-effective, simple, and high sensitivity and specificity inspection methods, which should be noticed and widely used in the future, especially in resource-limited grass-roots testing institution or in cases with inconclusive immunostains or insufficient material.

Laparoscopic-Assisted Endoscopic Resection of a Gastric Leiomyoma

Leiomyomas are infrequent benign intestinal tumors that can arise at any age and location within the gastrointestinal (GI) tract. These tumors can cause symptoms including abdominal pain, obstruction, intussusception, volvulus, GI bleeding, or a mass and should be resected if symptomatic. Open surgical resection is considered the standard for removing these tumors. However, recent improvements in endoscopic and laparoscopic equipment have made it possible to utilize minimally invasive techniques of tumor removal including complete endoscopic resection or endoscopic-assisted laparoscopic resection. We present the case of an adolescent female with a large mass located at the gastroesophageal junction (GEJ) causing GI bleeding. Given the location of the mass near the GEJ and the morbidity associated with surgical resection, we performed laparoscopic-assisted complete endoscopic resection of tumor. In addition, this tumor had an unusual immunohistochemical-staining pattern, with focal expression of markers more often seen in GI stromal tumors, elucidating a gray area between these two tumor classes with potential implications for patient follow-up. Laparoscopic-assisted endoscopic resection of benign tumors is a useful technique that can be employed to facilitate resection of mucosal and subserosal masses near the GEJ with minimal morbidity.

Genetic analysis of intraoral KIT-positive gastrointestinal stromal tumor (GIST)

Gastrointestinal stromal tumors (GISTs), mesenchymal neoplasms originating from the cells of Cajal, usually appear in the gastrointestinal tract and abdomen. They often mimic other lesions, including smooth muscle cell tumors and neurogenic tumors. This study presents a case in which a GIST appeared over a 2-month period and was treated by excision and curettage, with no sign of recurrence during the next 42 months. The study also aims to characterize the GIST. Histopathologic analysis and KIT gene amplification and sequencing were performed. On mutation analysis of the GIST material, the novel 69338Tdel mutation was found in exon 11, and the diagnosis of intraoral stromal tumor was made. GISTs in the intraoral region display pathologic properties similar to others developed throughout the gastrointestinal system. Diagnosis is the first step of treatment for a patient. The discovery of oncogenic KIT mutations in GISTs has led to the development of targeted molecular therapy using tyrosine kinase inhibitors. This study investigates the histopathologic and molecular diagnostics of GISTs, and, to the authors' knowledge, it represents the first genetic study of a GIST developing in the intraoral region.

Estrogen and progesterone receptors expression in gastrointestinal stromal tumors and intramural gastrointestinal leiomyomas

Gastrointestinal stromal tumors (GISTs) and leiomyomas of the gastrointestinal tract both may present as intramural smooth muscle cell tumors. Immunohistochemically, these tumors demonstrate different spectrums of protein expression, which helps in differential diagnosis. Leiomyomas of the uterine type are similar by the spectrum of protein expression to gastrointestinal leiomyomas, but they express in addition both estrogen (ER) and progesterone (PR) receptors, which makes hormonal therapy possible for these tumors. In the current study, we investigated expression of ER and PR in GISTs and intramural gastrointestinal leiomyomas. Our data demonstrate that none of the 22 cases of gastrointestinal leiomyomas nor 19 cases of GIST were positive for either ER or PR expression. In contrast, leiomyomas of the uterine type were strongly positive for both ER and PR. Our data demonstrate that GIST and gastrointestinal leiomyomas differ from leiomyomas of the uterine type by the expression of ER and PR. Immunostaining for ER and PR may be a useful tool to distinguish these tumors and more precisely to plan further clinical interventions.