Schwannomas are mesenchymal tumors that are characteristically benign and slow growing, which originate from any nerve with Schwann cell sheath. Gastrointestinal schwannomas are rare with distinct morphologic features as compared to schwannomas of soft tissue or central nervous system. A 77-year-old male patient was diagnosed with gastrointestinal stromal tumor based on radiological findings and clinical impression when he presented with worsening abdominal discomfort and pain. He underwent distal gastrectomy however histopathological examination of the tumour revealed schwannoma. This case report presents a rare case of a symptomatic gastric schwannoma, whose definitive diagnosis was established by histopathological and immunohistochemical findings postoperatively.
Gastrointestinal stromal tumour (GIST) is a common mesenchymal tumour arising in the gastrointestinal tract, but not frequently encountered in the rectum. Herein, we describe a case of a rectal GIST which mimicked histomorphological features of a schwannoma; thus, making intraoperative frozen section evaluation challenging. Although subsequent immunohistochemistry and molecular findings readily confirmed the diagnosis of a GIST, we wish to draw attention to three clues that will help the pathologist steer clear of this potential diagnostic pitfall. One, GISTs are relatively more common than schwannomas in the rectum. Two, schwannomas usually have very little mitoses. Three, rectal GISTs commonly exhibit nuclear palisades. We also discuss the diagnostic, prognostic and therapeutic functions of immunohistochemical and molecular investigations. As the surgical intent for rectal GISTs is for en-bloc excision with wide margins, we surmise that the intraoperative consult should include GIST as a possible differential diagnosis for rectal mesenchymal tumours. In view of the potential for neoadjuvant treatment with imatinib before surgical excision to preserve sphincter function, a multidisciplinary approach is recommended for establishing most effective treatment strategy in these rare complex cases.
Gastrointestinal stromal tumour (GIST) is a rare but most common mesenchymal tumour in the gastrointestinal tract. Although GIST research has been carried out extensively worldwide, it has yet to be studied in Malaysia. To establish the immunohistochemical expression pattern of CD117 (c-KIT), CD34, S-100 and Desmin, the incidence of c-KIT and PDGFRA genes mutation in GISTs, and correlate it with clinicopathological parameters. Eleven clinically diagnosed GISTs were stained for CD117, CD34, Desmin and S-100 protein by immunohistochemical technique, and c-KITand PDGFRA gene mutations were studied by PCR-CSGE-DNA sequencing method. All GISTs (7 cases) stain positive for CD117, and co-expressed CD34. None of these cases express Desmin, and only one expressed S-100 protein focally. Fifty-seven percent (4/7 cases) of GIST harboured mutations at exon 11 of c-KIT gene, and they were all high risk and malignant cases. No mutation was detected at exons 9, 13 and 17 of KIT gene, and exons 12 and 18 of PDGFRA gene. Immunohistochemistry using a panel of antibodies shows consistent pattern of CD117 and CD34 expression in GIST, and mutational study may be a useful prognostic marker for kinase inhibitor treatment of GIST.
PURPOSE: To study histomorphological and immunohistochemical patterns of gastro-intestinal stromal tumours (GISTs) in Malaysia.
MATERIALS AND METHODS: A total of 29 GIST cases from Hospital Tuanku Ja'afar, Seremban ,were studied retrospectively over a period of 10 years from January 2002 to December 2011. Patient demographic data like age, sex and etnicity were collected. Tumour characteristics like site, maximum dimension and specimen type were analysed. Evaluation was according to established criteria into very low, low, intermediate and high-risk categories. Immunohistochemical characteristics were also analysed.
RESULTS: The mean age of patients was 59.7 years. Males (59%) were found to be more commonly affected than females (41%). The Chinese (45%) were commonly affected than Malays (41%), and Indians (10%). The most common symptom was pain in the abdomen (13.8%). More than half of the cases were seen in stomach (53%). The tumour size ranged from 1.5 cm to 17 cm with a mean of 6.94cm. Microscopic findings revealed that the spindle cell type was the most common (76%). It was observed that the majority of the cases (48%) were categorised in the intermediate risk group. Immunohistochemical staining showed positivity for CD117 (78.6%), CD34 (71.4%), vimentin (86.2%), S-100 (27.6%), SMA (35.7%), PKC THETA (46.4%) and PDGRFA (67.9%).
AIM: To study the clinical features, histology and immunohistochemical properties of gastrointestinal stromal tumours (GISTs); and establish any parameters that can help prognosticate the malignant potential.
METHODS: Twenty-six patients with GISTs who were seen in Sultanah Aminah Hospital Johor, Malaysia from 1999 to 2003 were selected for study. Patient, clinical characteristics and outcome based on surgical records were analysed. Tumour variables (tumour size, cellularity, mitotic count, necrosis and haemorrhage) were compared between very low to low risk groups and intermediate to high risk groups. The immunohistochemical properties of GISTs were also studied.
RESULTS: Patients with GISTs presented mainly with pain, palpable mass or gastrointestinal tract bleeding. The tumours were seen in stomach (50%) followed by small intestine (38.5%) and rectum (11.5%). In the period of study, six patients had metastasis, mainly in the liver or peritoneum. Immunoreactivity for CD117, CD34, vimentin, S100, neuron specific enolase, alpha-smooth-muscle-actin and desmin were observed in 100%, 76.9%, 61.5%, 46.1%, 80.8%, 11.5% and 0% of tumours respectively. The behaviour of GISTs was largely dependent on tumour size and number of mitosis. Necrosis and haemorrhage were seen in tumours with high risk potential.