History:

A 61-year-old man has noted lower back pain for about a year accompanied by an 18 kg weight loss. You can find nothing notable on physical examination.

Image 5.1:

This is the gross appearance of the neoplasm. The mass is quite large, with a yellow-tan cut surface and irregular borders. It is surrounded by soft tissue and muscle.

Image 5.2:

This is the low power microscopic appearance. Describe it. The cells have a spindly appearance, and the neoplasm is quite cellular.

Image 5.3:

This is the high power microscopic appearance. Describe it. The cells are markedly hyperchromatic and pleomorphic, with mitoses present. There is no discernible pattern.

Answers:

1. What further procedure(s) can be done to determine what his problem is?

A CT or MRI scan may help. In this case, a CT scan revealed a mass in the left thigh region. He was taken to surgery and the mass was removed.

2. What are some reasons for such a profound weight loss?

Most of the time, such profound weight loss is involuntary (i.e., not from going on a diet) and usually points to a neoplasm (though sometimes chronic infectious diseases such as tuberculosis may be associated with weight loss).

3. What use can be made of immunohistochemistry to determine the nature of the neoplasm?

Immunohistochemical stains on tissue biopsies can help to determine the type of neoplasm when the H&E histopathologic appearance is that of an "anaplastic" or "undifferentiated" neoplasm. Staining with intermediate filaments such as vimentin are typical of sarcomas. Staining with cytokeratins point to an epithelial origin (a carcinoma). Staining with leukocyte comman antigen suggests a lymphoma.

4. What features distinguish a carcinoma from a sarcoma? How are tumors classified on the basis of their embryologic origin?

A carcinoma arises from epithelium (embryologic ectoderm) and tends to be composed of cells that are polygonal and form cohesive nests or clusters. Keratin formation in cell clusters suggests squamous cell carcinoma, while mucin production in glandular configurations suggests adenocarcinoma. Carcinomas tend to spread to lymph nodes. A sarcoma arises from mesenchymal cells of mesodermal embryologic origin ("soft tissues"). Sarcomas tend to be composed of spindle cells. They often form big masses.

5. What determines the prognosis with neoplasia?

Prognosis is determined by the cell type, location, grade, and stage. Obviously, a benign tumor such as a lipoma on the trunk can grow slowly for years and produce no problems. However, an oat cell carcinoma that grows quickly and spreads early and has no early signs or symptoms will have a very poor prognosis.