Pigmented Basal Cell Carcinoma: Increased Melanin or Increased Melanocytes?
Jessica A Kozel, Edward M Prodanovic, Maria Yadira Hurley. Saint Louis University, Saint Louis, MO
Background: Pigmented basal cell carcinoma (pBCC) often mimics melanoma clinically and occasionally histologically. Although infrequent, there can be collision tumors between pBCCs and melanocytic neoplasms. Melanocytic immunohistochemical stains such as Mart-1/Melan-A may be used in select cases. Therefore, we sought to determine whether pBCC actually contains more melanocytes than non-pigmented basal cell carcinoma (nBCC) or if pBCCs simply have a relative increase in melanin production.
Design: Under an IRB-approved protocol, fifteen pBCCs from the head and neck (sun-exposed) and fifteen pBCCs from the trunk (sun-protected) were obtained from our case files. In addition, fifteen nBCCs (8 from the head and neck, 7 from the trunk) were obtained as controls. All cases were reviewed by a board-certified dermatopathologist to confirm the historical diagnosis prior to inclusion. Patient age and gender were also recorded prior to de-identification. Mart-1/Melan-A staining was performed on cases and controls. An evaluator identified the area of greatest staining density on low-power then manually counted and recorded the number of positively staining cells in a single 400x field in this area.
Results: The mean count of melanocytes/400x HPF in pBCCs from the head and neck was 101.9 compared to 27.4 in nBCCs (p=0.002). The mean count of melanocytes/400x HPF in pBCCs from the trunk was 122.5 compared to 34.9 in nBCCs (p=0.002) (Figure 1).
Age and gender were comparable among the study cases and controls (Figure 2).
Conclusions: Our study concludes that pBCCs have an increased number of melanocytes as compared with nBCCs at site-matched locations. This information may aid in the interpretation of melanocytic immunohistochemical stains in pBCCs especially cases in which malignant melanoma is in the differential or a collision tumor is present.
Wednesday, March 21, 2012 1:00 PM
Poster Session VI # 126, Wednesday Afternoon