Diagnosis of Desmoplastic Reaction by Immunohistochemical Analysis, in Biopsy Specimens of Early Colorectal Carcinomas, Is Efficacious in Estimating the Depth of Invasion

The aim of our study was to evaluate the diagnosis of desmoplastic reaction (DR) by immunostaining for alpha-smooth muscle actin (alpha SMA) and desmin, for predicting the depth of submucosal invasion in biopsy specimens of early colorectal carcinomas (CRCs). Thirty-eight cases of non-pedunculated early CRCs were included in this study. Positive for DR was defined as alpha SMA-positive and desmin-negative stroma in the CRC. The depth of submucosal invasion was measured in endoscopically or surgically resected specimens and the lesions were subsequently divided into two groups: Group A (carcinoma in situ/intramucosal carcinoma and submucosal invasive carcinoma with a depth <1000 mu m) and Group B (submucosal invasion with a depth >= 1000 mu m). Twenty-one cases were DR-positive and 17 were DR-negative. No statistical significance was found between the DR with regard to tumor size, location and histological type. All DR-positive cases belonged to Group B whereas 14 (82.4%) DR-negative lesions belonged to Group A (p < 0.001). The sensitivity, specificity, positive and negative predictive values and accuracy of DR positivity for diagnosis of Group B were 87.5%, 100%, 100%, 82.4% and 92.1%, respectively. Conclusively, detection of DR in biopsy specimens with ancillary immunohistochemistry (aSMA/desmin) would help in preoperative diagnosis for the depth of submucosal invasion of early CRC.