Juthamas Ngamwiseschaikul, MD1, Juthamas Wongphum, BSc1, Somboon Keelawat, MD1 1Departments of Pathology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand, Corresponding author: Somboon Keelawat, M.D. Department of Pathology, Faculty of Medicine, Chulalongkorn University,
Pathumwan, Bangkok, Thailand 10330 Tel: 662-256-4235 Fax: 662-652-4208 Email: email@example.com Received: 6 April 15; Accepted : 5 June 15
Objective: To evaluate the usefulness of α-smooth muscle actin (α-SMA) expression of reactive myofibroblastic cells within desmoplastic reaction tissue for distinction between invasive squamous cell carcinoma (SCC) and pseudoepitheliomatous hyperplasia (PEH). Materials and Methods: Twenty-one cases of SCC and 20 cases of PEH were immunologically stained with α-SMA antibody. The immunohistochemical staining is evaluated and recorded in percentage of staining area in stromal tissue per the total stroma obtained in each slide (excluding blood vessels’ wall, muscle, inflammatory
and reparative tissue areas). Results: The average percentage of positive staining is significantly higher in the reactive stroma of SCC compared to the stroma of PEH (18.57% VS 1.75%) (p=0.014). With the cut off value at 10% staining, the sensitivity of staining for diagnosis of SCC is 52.38%, specificity 95%, PPV 91.67%, NPV 65.52%. Conclusion: The α-SMA staining is highly specific for detection of desmoplastic reaction in SCC. However,
the weakness of this marker is its low sensitivity.