Immunolabeling Pattern of Podoplanin (D2-40) May Distinguish Basal Cell Carcinomas from Trichoepitheliomas: A Clinicopathologic and Immunohistochemical Study of 49 Cases
P Ortega, S Suster, D Stockman, C Bengana, JA Plaza. Medical College of Wisconsin, Milwaukee, WI
Background: Basal cell carcinomas (BCC) and trichoepitheliomas, most of the time are effectively distinguished based on defined histologic criteria; however, they may pose diagnostic challenge in rare occasions when the morphologic distinction between these two neoplasms are not clear. Their distinction is clinically important because the risk of progressive disease in BCC can be problematic, and trichoepitheliomas misinterpreted as BCC burdens the patient with an inaccurate diagnosis that may result in inappropriate surgery. Podoplanin (D2-40) is a well known lymphatic endothelial surface marker that has also been postulated to be upregulated in the outer root sheath of hair follicles and cutaneous neoplasms, such as adnexal tumors, squamous cell carcinomas, etc.
Design: We studied the expression of podoplanin (D2-40) by immunohistochemistry to determine if this marker can reliably separate these neoplasms. Immunolabeling for podoplanin was scored as negative, focally positive or diffusely positive (cytoplasmic membrane staining). We defined negative as no reactivity, focally positive as staining in 1% to 25% of the tumor cells and greater than 25% was defined as diffuse staining. A total of 49 cutaneous tumors, including 22 cases of trichoepitheliomas and 27 cases of follicular BCC were examined. Of the 27 cases of BCC, 18 cases were located in the head and neck area, 5 in upper extremities, and 4 in the back. Of the 22 cases of trichoepitheliomas, all the 22 cases were located in the head and neck area.
Results: Podoplanin expression was present in 21/22 cases or trichoepitheliomas; 11 cases were diffusely positive (50%), 10 cases were focally positive (45.45%), and 1 case was negative (4.54%). Podoplanin expression was present in 6/27 cases of BCC; 2 cases were diffusely positive (7.40%), 4 cases were focally positive (14.8%), and 21 cases were negative (77.7%).
Conclusions: In summary, podoplanin expression was only weakly and focally positive in BCC (22% of cases) and diffusely and weakly positive in trichoepitheliomas (95.45% of cases). The sensitivity and specificity of podoplanin immunoreactivity to separate trichoepitheliomas from BCCs was 95.5% and 77.8% respectively. This data suggests that podoplanin expression could be a useful and potential marker to distinguish BCC from trichoepitheliomas, especially when there is a high index of histologic suspicion for either of these tumors.
Wednesday, March 24, 2010 1:00 PM
Poster Session VI # 88, Wednesday Afternoon