A 54-year-old male presents with an enlarged left-sided supraclavicular lymph node. The node is painless and stony hard on palpation. The node biopsy reveals anaplastic cells that stain positive for keratin. Which of the following is the most likely origin of the cells detected on the biopsy?

Question

A 54-year-old male presents with an enlarged left-sided supraclavicular lymph node.  The node is painless and stony hard on palpation.  The node biopsy reveals anaplastic cells that stain positive for keratin.  Which of the following is the most likely origin of the cells detected on the biopsy?

Quizplus · Accepted Answer

Keratins are a broad group of intermediate filaments present in epithelial cells. Immunohistochemistry stains that employ keratin markers are used by pathologists in the identification of poorly differentiated tumors or tumors with an unclear site of origin. Tumors that stain positive for keratin include carcinomas, mesotheliomas, thymomas, various sarcomas, trophoblastic tumors, and desmoplastic small round cell tumors. (Choice A) Lymphocytes can be identified immunohistochemically with a special stain for the pan T cell marker CD3, among others. (Choice C) Muscle tissue can be identified immunohistochemically with special stains for smooth muscle actin, caldesmon, or desmin, among others. (Choice D) Endothelium can be identified immunohistochemically with special stains for CD34 and von Willebrand's factor, among others. (Choice E) Glial cells can be identified immunohistochemically with a special stain for glial fibrillary acidic protein. Educational Objective: Keratin is a marker of epithelial cell origin.

A 54-Year-Old Male Presents with an Enlarged Left-Sided Supraclavicular Lymph