The Sal-like protein 4, SALL4 is a zinc finger transcription factor located on chromosome 20q13.13-13.2. It is essential during development by maintaining embryonic stem cell pluripotency and self-renewal. Mutations in SALL4 lead to acro-renal-ocular and Okihiro syndromes, a disorder of the eyes and abnormalities of bones in the arms and hands.

Recently, SALL4 has been identified as a novel sensitive diagnostic marker for germ cell tumors. Strong SALL4 staining was observed in all seminoma/dysgerminoma/germinomas, embryonal carcinomas, and yolk sac tumors, yielding 100% sensitivity for these malignancies. Compared with _-fetoprotein and glypican-3, SALL4 demonstrated superior sensitivity in detecting yolk sac tumors. Focal SALL4 staining was also observed in choriocarcinomas (66-71%) and teratomas (50-64%).

In non-germ cell tumors, SALL4 is expressed in all cases of acute myeloid leukemia, and majority of precursor B-cell acute lymphoblastic lymphomas (79%). In a large immunohistochemical study of >3200 cases, SALL4 was also detected in ~20% of cases of ovarian, urothelial and gastric adenocarcinomas, and <5% in mammary, colorectal, prostatic and squamous cell carcinomas.