GIT liver Q&A

Question 1

A 42-year-old man presented to the hospital with right upper quadrant pain. He was found to have multiple masses in the liver that were found to be malignant on H&E staining of a biopsy sample. Your initial history, physical examination, and laboratory tests, including prostate-specific antigen, are unrevealing. Lung, abdominal, and pelvic CT scans are unremarkable. He is an otherwise healthy individual with no chronic medical problems. Which immunohistochemical markers should be obtained from the biopsy tissue?

A. α-Fetoprotein
B. Cytokeratin
C. Leukocyte common antigen
D. Thyroglobulin
E. Thyroid transcription factor 1

Answer 1

B.

Patients with cancer from an unknown primary site present a common diagnostic dilemma. Initial evaluation should include history, physical examination, appropriate imaging, and blood studies based on gender (e.g., prostate-specific antigen in men, mammography in women). Immunohistochemical staining of biopsy samples using antibodies to specific cell components may help elucidate the site of the primary tumor. Although many immunohistochemical stains are available, a logical approach is represented in Figure III-51. Additional tests may be helpful based on the appearance under light microscopy or the results of the cytokeratin stains. In cases of cancer of unknown primary, cytokeratin staining is usually the first branch point from which the tumor lineage is determined. Cytokeratin is positive in carcinoma because all epithelial tumors contain this protein. Subsets of cytokeratin, such as CK7 and CK20, may be useful to determine the likely etiology of the primary tumor. Leukocyte common antigen, thyroglobulin, and thyroid transcription factor 1 are characteristic of lymphoma, thyroid cancer, and lung or thyroid cancer, respectively. α-Fetoprotein staining is typically positive in germ cell, stomach, and liver carcinoma.