Although the terminology applied to neoplasms can be confusing for a number of reasons, certain
generalizations can be made. The suffix oma, applied by itself to a tissue type, usually indicates
a benign tumor. Some malignant neoplasms, however, may be designated by the oma suffix
alone; these include lymphoma, melanoma, and thymoma. Rarely, the oma suffix is used to describe
a nonneoplastic condition such as granuloma, which is often not a true tumor, but a mass
of granulation tissue resulting from chronic inflammation or abscess. Malignant tumors are
indicted by the terms carcinoma (epithelial in origin) or sarcoma (mesenchymal in origin) preceded
by the histologic type and followed by the tissue of origin. Examples of these include adenocarcinoma
of the breast, squamous cell carcinoma of the lung, basal cell carcinoma of skin,
and leiomyosarcoma of the uterus. Most human malignancies arise from epithelial tissue. Those
arising from stratified squamous epithelium are designated squamous cell carcinomas, whereas
those emanating from glandular epithelium are termed adenocarcinomas. When a malignant
tumor no longer resembles the tissue of origin, it may be called anaplastic or undifferentiated. If a
tumor is metastatic from another tissue, it is designated, for example, an adenocarcinoma of
the colon metastatic to liver. Some tumors arise from pluripotential primitive cell types and may
contain several tissue elements. These include mixed mesenchymal tumors of the uterus, which
containcarcinomatousandsarcomatous elements, and teratocarcinomas of the ovary, which may
contain bone, cartilage, muscle, and glandular epithelium.
Neoplasms of the hematopoietic system usually have no benign counterparts. Hence the terms leukemia and lymphoma always refer to a malignant disease and have cell-type designations
such as acute or chronic myelogenous leukemia, Hodgkin’s or non-Hodgkin’s lymphoma,
and so on. Similarly, the term melanoma always refers to a malignant neoplasm derived
from melanocytes.
