Comprehensive Morphological and Immunohistochemical Evaluation of Gastrointestinal Stromal Tumors: Insights From a Tertiary Care Center.

Introduction Gastrointestinal stromal tumors (GISTs) represent the most common mesenchymal neoplasms of the gastrointestinal tract, typically originating from the interstitial cells of Cajal. Accurate histopathological assessment and immunohistochemical profiling are pivotal for diagnosis and risk stratification. This study aimed to evaluate the clinicopathological characteristics and immunohistochemical expression patterns of GISTs diagnosed at a tertiary care center. Methods A retrospective analysis was conducted on 30 histologically confirmed cases of GIST over a seven-year period. Formalin-fixed, paraffin-embedded tissue samples were reviewed using hematoxylin and eosin staining and subjected to immunohistochemistry. Parameters assessed included patient demographics, tumor location, histological subtype, mitotic index, and immunoreactivity for CD117, DOG1, and CD34. Results The cohort comprised 19 men and 11 women, with a mean age of 62.1 years. The small intestine had the most number of cases, i.e., eight cases (26%), followed by the stomach, which had seven cases (24%). Spindle cell morphology was predominant (86%), followed by epithelioid and mixed patterns (7% each). Most tumors were low-grade (60%), with a mitotic rate of <5 per 50 high-power fields. Immunohistochemically, DOG1 showed the highest positivity (97%), followed by CD117 (84%) and CD34 (70%). Smooth muscle actin (SMA), desmin, and S-100 showed variable positivity. Conclusion This study highlights a male predominance and a predilection for gastric and small intestinal involvement in GISTs. Spindle cell morphology and low mitotic activity were common histological features. Immunohistochemistry remains indispensable for diagnosis, with DOG1 demonstrating superior sensitivity. These findings reinforce the critical role of integrated histopathological and immunohistochemical evaluation in the accurate diagnosis and management of GISTs.