PRL and pituitary adenocarcinoma: Pernicone et al. [4] reported a clinicopathologic study of 15 patients with pituitary carcinomas in which the overall latency period ranged from just over three months to 18 years (median 5 years); the latency was nearly twice as long for ACTH-producing tumors as for prolactin (PRL) tumors (9.5 vs. 4.7 years).