Histomorphological Spectrum and Immunohistochemical Features of Gastrointestinal Stromal Tumour: A Series of Eight Cases (original) (raw)

2022, Journal of Clinical and Diagnostic Research

The GISTs arise from the interstitial cells of Cajal, the pacemaker cells, comprising <1% of all primary GIT tract neoplasms [1]. The peak age of occurrence is 60-65 years, equally affecting males and females, which may be detected incidentally radiologically or present with abdominal symptoms [2]. More than 60% of them take place in the stomach. EGIST occur in the omentum, mesentery, retroperitoneum, and perineum. Histomorphologically, GISTs are hypocellular to densely cellular lesions [1]. The identification of primary mutations in KIT (tyrosine-protein kinase) (75-80%) or Platelet-derived growth factor receptor alpha (PGFRA) (7-15%) genes by IHC has revolutionised the diagnosis and led to the development of targeted therapy [1]. The diagnosis and treatment of small GISTs are important as surgery is the mainstay of treatment in Asian countries as compared to medical therapy in western countries. Optimal treatment of GISTs requires a team effort, including gastroenterologists, surgical and medical oncologists, pathologists, and radiologists [3]. This case series was done to study the clinicopathological, histomorphological, and IHC spectrum of GISTs along with their risk stratification according to the modified Miettinen and Lasota's algorithm [4]. The American Joint Committee on Cancer (AJCC) Cancer Staging (TNM) 8 th edition was used for staging and grading [5]. Following permission from the Institutional Ethics Committee of Clinical Research (No. 289/2021) was approved, eight patients with GISTs diagnosed between January 2017 and December 2020 are presented in this case series. CASE SERIES Case 1 A 36-year-old man presented to the Department of Surgery with chief complaints of epigastric discomfort for a month and vomiting for five days. A well-defined, spherical, broad-based isoechoic lesion measuring 4.3x3.4 cm with central anechoic cystic regions was seen on Ultrasound Sonography (USG), emerging from the wall of the pylorus producing luminal compression and stomach dilatation. A comparable tumour was detected using Contrast-Enhanced Computer Tomography (CECT), which raised the probability of GIST. Based on clinical findings and radiological investigations, the possibility of GIST or leiomyoma was considered. The histopathology laboratory received a 0.5 cm size upper GI scopy biopsy which microscopically showed mainly moderate chronic inflammation with no submucosal tissue. Eventually, excision of mass with distal stomach, pylorus and omentum was performed. Grossly, a submucosal tumour in region of pylorus measuring 4.0x3.5x3.0 cm was seen. The cut surface of the tumour was well-circumscribed, greyish-white with a few cystic areas. Sections from the tumour showed spindle cells arranged in fascicles and whorls with a round to oval nucleus with minimal pleomorphism and eosinophilic cytoplasm with pointed ends [Table/Fig-1a]. Mitosis was <5 per 20-25 hpf (high power field). Omentum was free from metastasis. A diagnosis of spindle cell tumour, suggestive of GIST, grade G1, very low-risk category was given. Strong, diffuse IHC positivity for CD117 [Table/Fig-1b] and vimentin confirmed the provisional diagnosis. S-100 was weakly positive and desmin was negative, which excluded neural and smooth muscle origin tumours. For six months there was no recurrence after which the patient was lost to follow-up. Case 2 A 75 year-old-male consulted a general surgeon at the Outpatient Department (OPD) for symptoms of increased frequency of stool with difficulty in defecation for six months and weakness for one year. For 20 days he felt a mass in the left iliac fossa. On