KLK3 and adenocarcinoma: Furthermore, a not-so-insignificant number of malignancies can also present with normal PSA levels; these include the broad group of nonepithelial (stromal and mesenchymal) and neuroendocrine malignancies, adenoid cystic carcinoma, squamous cell carcinoma, adenosquamous carcinoma, and around 10% of higher grade conventional adenocarcinomas [6, 7].