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This article is from the The Biopsy Report: A Patient's Guide, by Ed Uthman uthman@neosoft.com with numerous contributions by others.

07 Biopsy: Glossary Of Important Diagnostic Terms

Finally, it may be useful to present a brief glossary of important
terms used in pathologic diagnoses. Terms in the definition that are
in ALL CAPS have their own entry.

ABSCESS

A closed pocket containing pus. Some abscesses are easily
diagnosed clinically, as they are painful and may "point out"
such that pus becomes visible, but deep and chronic abscesses
may just look like a TUMOR clinically and require biopsy to
distinguish them from neoplasm.

ATYPICAL

The simple, straightforward definition would be "unusual,"
but "atypical" means much more than that. In a diagnosis, the
use of the term atypical is a vague warning to the physician
that the pathologist is worried about something, but not
worried enough to say that the patient has cancer. For
instance, lymphomas (cancers of the lymph nodes) are
notoriously difficult to diagnose. Some lymph node biopsies
are very disturbing but do not quite fulfil the criteria for
cancer. Such a case may be diagnosed as "atypical lymphoid
HYPERPLASIA." Other important atypical hyperplasias are those
of the breast (atypical ductal hyperplasia and atypical
lobular hyperplasia) and the lining of the uterus (atypical
endometrial hyperplasia). Both of these conditions are
thought to be precursor warning signs that the patient is at
high risk of developing cancer of the respective organ
(breast and uterus).

CARCINOMA

A malignant NEOPLASM whose cells appear to be derived from
EPITHELIUM. This word can be used by itself or as a suffix.
Cancers composed of columnar epithelial cells are often
called adenocarcinomas. Those of squamous cells are called
squamous cell carcinomas. The type of cancer typically
recapitulates the type of epithelium that normally lines the
affected organ. For instance, almost all cancers of the colon
are adenocarcinomas, and columnar epithelium is the normal
lining of the colon. There are exceptions, however.

DYSPLASIA

An ATYPICAL proliferation of cells. This may be loosely
thought of as an intermediate category between HYPERPLASIA
and NEOPLASIA. It finds its best use as a term to describe
the phenomenon in which EPITHELIUM proliferates and develops
the microscopic appearance of neoplastic tissue, but
otherwise tends to "behave itself" and continues to line body
surfaces without actually invading them, as a true malignant
neoplasm would do. It may be convenient (but not totally
accurate) to consider dysplasia as a "pre-cancer" or an
incipient cancer. Probably the most commonly occurring type
of dysplasia is that of the cervix of the uterus, where a
progression from dysplasia to neoplasia can be clearly
demonstrated. Other dysplasias, such as those of the breast
and prostate, are more difficult to clearly relate to
neoplasia at this time.

EPITHELIUM

A specialized type of tissue that normally lines the surfaces
and cavities of the body. There are three main types: 1)
columnar epithelium, which lines the stomach, intestines,
trachea and bronchi, salivary and other glands, pancreas,
gallbladder, nasal cavity and sinuses, uterus (including
inner cervix), Fallopian tubes, kidneys, testes, vasa
deferentia, and other ductal structures, 2) stratified
squamous epithelium, which lines the skin, oral cavity,
throat, esophagus, anus, outer urethra, vagina, and outer
cervix, and 3) transitional epithelium (urothelium), which
lines the urine-collecting part of the kidneys, the ureters,
bladder, and inside part of the urethra.

GRANULOMA

A special type of INFLAMMATION characterized by accumulations
of macrophages, some of which coalesce into "giant cells."
Granulomatous inflammation is especially characteristic of
tuberculosis, some deep fungal infections (like
histoplasmosis and coccidioidomycosis), sarcoidosis (a
disease of unknown cause), and reaction to foreign bodies.

HYPERPLASIA

A proliferation of cells which is not NEOPLASTIC. In some
cases, this may be a result of the body's normal reaction to
an imbalance or other stimulus, while in other cases the
physiologic cause of the proliferation is not apparent. An
example of the former process is the enlargement of lymph
nodes in the neck as a result of reaction to a bacterial
throat infection. The lymphocytes which make up the node
divide and proliferate, taking up more volume in the node and
causing it to expand. An example of hyperplasia in which the
stimulus is not known is benign prostatic hyperplasia (BPH),
in which the prostate gland enlarges in older men for no
known reason. While hyperplasias do not invade other organs
or METASTASIZE to other parts of the body, they can still
cause problems because of their local physical expansion. For
instance, in BPH, the enlarged prostate pinches off the
urethra and interferes with the flow of urine. If untreated,
permanent kidney damage can result.

INFLAMMATION

A reaction, usually mediated by the immune system, to noxious
stimuli, manifested clinically by swelling, pain, tenderness,
redness, heat, and/or loss of function of the affected part.
To a pathologist, however, inflammation means the
infiltration of certain immune system cells into the tissue
or organ being examined. These inflammatory cells include 1)
neutrophils, which are the white blood cells that make up pus
and are seen in acute or early inflammations, 2) lymphocytes,
which are typically seen in more chronic or longstanding
inflammations, and 3) macrophages (histiocytes), which are
also seen in chronic inflammation. Some types of inflammation
are readily diagnosable by the primary care physician, such
as an infected skin wound that is tender, hot, and draining
pus. Other types of inflammation are not so readily apparent
clinically and require biopsy to distinguish them from
neoplasms. The suffix "-itis" is appended to a root word to
indicate "inflammation of _____." For example, cervicitis,
pharyngitis, gastritis, and thyroiditis are inflammations of
the cervix, pharynx (throat), stomach, and thyroid gland,
respectively.

LESION

This is a vague term meaning "the thing that is wrong with
the patient." A lesion may be a TUMOR, an area of
INFLAMMATION, or an invisible biochemical abnormality (like
the abnormality of the sensitivity of the body's cells to
insulin in adult-onset diabetes).

METAPLASIA

The phenomenon by which one type of tissue is replaced by
another type. This often results from chronic irritation of
an EPITHELIAL lining. A good example is the cervix, in which
chronic irritation and INFLAMMATION causes the relatively
delicate normal columnar epithelium to be replaced by tougher
squamous epithelium (similar to that which normally lines the
vagina, which is naturally "built tougher" for obvious
reasons). This phenomenon is called "squamous metaplasia." In
it's pure state, metaplasia is not harmful, but some
metaplasias are markers for increased risk of more serious
diseases. For instance, a type of intestinal metaplasia of
the stomach (in which columnar epithelium of the intestinal
type replaces that of the gastric type) is considered a risk
factor for the subsequent development of cancer of the
stomach.

METASTATIC

Of or pertaining to METASTASIS, or the process by which
malignant NEOPLASMS can shed individual cells, which can
travel through the lymph vessels or blood vessels, lodge in
some distant organ, and grow into tumors in their own right.
There are two major routes of metastasis, 1) hematogenous, in
which the cells travel through the blood vessels, and 2)
lymphogenous, in which the lymphatic vessels conduct the
cancer cells. In the case of lymphogenous metastasis, the
metastatic tumors can grow from cancers cells entrapped in
the lymph nodes that collect the lymph draining from the
organ where the original cancer has developed, causing the
nodes to enlarge. In the case of breast cancer, the axillary
(underarm) nodes are the first to become involved. In the
case of cancer of the larynx (voice box), the nodes on either
side of the neck (cervical nodes) are first. Hematogenous
metastases tend to deposit in the lungs, liver, and brain.
Many cancers metastasize both lymphogenously and
hematogenously. Most cancer operations attempt to remove not
only the cancerous organ, but also the lymph nodes that drain
that organ. Some types of cancer, especially the most common
ones (lung, breast, colon, and prostate cancers) tend to
metastasize to lymph nodes first. Pathologic examination of
these nodes is important in "staging" the cancer, which gives
the patient and the doctor some idea as to the odds of curing
the cancer and how to best treat it. A typical diagnosis of a
specimen of a "radical" removal of a cancer may read like,

Breast, left, mastectomy: infiltrating ductal
cancinoma; three of fifteen axillary nodes
contain metastatic carcinoma.

NECROSIS

Death of tissue. Necrosis may be seen in inflammatory
conditions, as well as in NEOPLASMS.

NEOPLASM, or NEOPLASIA

A "new growth" of the body's own cells, a proliferation of
cells no longer under normal physiologic control. These may
be "benign" or "malignant." Benign neoplasms are typically
tumors (lumps or masses) that, if removed, never bother the
patient again. Even if they are not removed, they are not
capable of destroying adjacent organs or "seeding" out to
other parts of the body. Malignant neoplasms, or "cancers,"
are those whose natural history (i.e., behavior if untreated)
is to cause the death of the patient. Malignancy is expressed
by 1) local invasion, in which the neoplasm extends into
vital organs and interferes with their function, 2)
METASTASIS, in which cells from the tumor seed out to other
parts of the body and then grow into tumors themselves,
and/or 3) paraneoplastic syndromes, in which the neoplasm
secretes metabolic poisons or inappropriately large amounts
of hormones that cause problems with functions of various
body systems.

-OMA

This suffix means "tumor" or "lump." It typically, but not
invariably, refers to a NEOPLASM ("GRANULOMA" is an
exception). In referring to neoplasms, benign ones are
typically referred to by a word, the prefix of which refers
to the organ or tissue of origin, followed by the suffix
"-oma." For example, leiomyoma, osteoma, chondroma, adenoma,
and hemangioma, refer to benign neoplasms of smooth muscle,
bone, cartilage, glandular tissue, and blood vessel tissue,
respectively. The analogous terms for malignant versions of
these neoplasms are, leiomyoSARCOMA, osteosarcoma,
chondrosarcoma, adenoCARCINOMA, and angiosarcoma.There are
exceptions to these vocabulary rules. For instance, hepatomas
and melanomas are all malignant. Other tumors, such as those
of the adrenal glands, cannot be classified into benign or
malignant categories based on pathologic appearance. Only
their behavior in time shows their true colors. An example is
pheochromocytoma (a tumor of the adrenal medulla), ten per
cent of which are malignant, but we don't know just by
looking at the tumor if a given case will fall into that ten
per cent.

POLYP

A structure consisting of a rounded head attached to a
surface by a stalk (also called a "pedicle" or "peduncle"). A
mushroom growing from the soil is an excellent example of
what a polyp looks like. Polyps my be HYPERPLASTIC,
METAPLASTIC, NEOPLASTIC, INFLAMMATORY, or none of the above.
The typical polyps removed from the colon of adults during
colonoscopy are benign neoplasms called tubular adenomas or
adenomatous polyps. The typical nasal polyps that develop in
people with allergies are inflammatory. The common benign
polyps removed from the cervix are of uncertain origin.

SARCOMA

A malignant NEOPLASM whose cells appear to be derived from
those other than EPITHELIUM. The connective tissues of the
body (fibrous tissue, muscle, bone, cartilage, fat, and
lining of joints) tend to give rise to sarcomas. In adults,
CARCINOMAS are much more common than sarcomas. This makes
sense, because as we age, our body linings are assaulted by
one noxious substance after the other. So it is no surprise
that those epithelial cells on the forefront of our battle
with the environment are the first to lose control of their
growth and development. In children, sarcomas make up a
greater proportion of cancers. While the connective tissues
of adults are rather stable and protected from environmental
assault, those of children are still growing and developing,
the cells dividing, raising the likelihood that something
will go haywire and cause a cell to lose control over its
growth.

SUPPURATION, SUPPURATIVE INFLAMMATION

A type of acute INFLAMMATION characterized by infiltration of
neutrophils at the microscopic level and formation of pus at
the gross level. ABSCESS is special type of suppurative
inflammation.

TUMOR

A mass or lump that can be felt with the hand or seen with
the naked eye. This may be a NEOPLASM, HYPERPLASIA,
distention, swelling, or anything that causes a local
increase in volume. The thing to remember is that not all
tumors are cancers, and not all cancers are tumors.

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