Loss anywhere in the CDKN2A region was associated with ulceration (P = 0.002). However, ulceration of the tumor was most significantly associated with reduced gene dosage at CDKN2B (one sided test P = 0.006, two sided P = 0.01) and regions coding for P14ARF (one sided P = 0.002, two sided P = 0.004). There was some evidence of an association between ulceration and reduced gene dosage at CDKN2A coding for CDKN2A, MTAP, and the interferon gene cluster (Table 1).