Adamantinoid basal cell carcinoma: a predictor of more-aggressive clinical behavior.

Background: Identifying histopathologic subtypes of basal cell carcinoma (BCC) associated with an aggressive clinical course helps the surgeon to anticipate the size of the postexcision defect and complexity of repair. During Mohs micrographic surgery (MMS), we have observed that BCC with adamantinoid histopathologic features tend to be clinically more aggressive.

Objective: To characterize the subtype of BCC with adamantinoid histopathologic features and determine whether it is clinically more aggressive than other BCCs.

Methods: A chart review was conducted of consecutive cases of MMS performed at Stanford University Medical Center for BCC from June 2002 through March 2004. Cases had been prospectively categorized as adamantinoid BCC if they met histopathologic criteria, including uniform clear areas around the individual tumor cells within tumor islands. We retrospectively compared adamantinoid and control cases in terms of patient age, sex, tumor location, number of Mohs stages required, area of post-Mohs defect, and type of repair.

Results: Four hundred eighty-nine cases of MMS for BCC were reviewed. Forty-four (9%) were adamantinoid BCC. Patients with adamantinoid BCC did not differ statistically from the control group in terms of sex (23% vs 32% female, p = .20) but tended to be older (median age 73 vs 66, p = .04; mean age 70 vs 65 years, p = .05). The distribution of cases on the head and neck differed significantly between the adamantinoid and control groups (p = .02), with more adamantinoid cases located on the nose and ears. Adamantinoid BCC required more stages for clear histologic margins (median 3.00 vs 2.00, p < .001; mean 3.68 vs 2.34, p < .001) and had larger post-Mohs defects (median 3.00 vs 1.68 cm(2) , p < .001; mean 4.24 vs 2.78 cm(2) , p = .02). Only 4.5% of adamantinoid BCC cases were able to heal by second intention, with 20.4% requiring complex primary closure. Staged flaps were performed in 13.6% of individuals with adamantinoid BCC.

Conclusions: Adamantinoid BCC is an aggressive histopathologic subtype in terms of number of stages for clear margins and size of post-Mohs defect. It may also require more-complex repairs. Recognition of this aggressive variant may benefit future patients by facilitating prediction of the clinical extent of tumors.