How are basal and squamous cell skin cancers diagnosed?

If an abnormal area of skin raises the possibility of skin cancer, certain medical exams
and tests such as a biopsy may be used to find out if it is cancer or some other skin
condition. If there is a chance the skin cancer may have spread to other areas of the body,
other tests may be done as well.
Signs and symptoms of basal and squamous cell skin 
cancers 
Skin cancers rarely cause bothersome symptoms until they become quite large. Then they
may bleed or even hurt. But typically they can be seen or felt long before they reach this
point.
Basal cell carcinomas often appear as flat, firm, pale areas or small, raised, pink or red,
translucent, shiny, waxy areas that may bleed after a minor injury. They may have one or
more abnormal blood vessels, a lower area in their center, and/or blue, brown, or black
areas. Large basal cell carcinomas may have oozing or crusted areas. They usually
develop on areas exposed to the sun, especially the head and neck, but they can occur
anywhere on the body.
Squamous cell carcinomas may appear as growing lumps, often with a rough, scaly, or
crusted surface. They may also look like flat reddish patches in the skin that grow slowly.
They commonly occur on sun-exposed areas of the body such as the face, ear, neck, lip,
and back of the hands. Less often, they form in the skin of the genital area. They can also
develop in scars or skin sores elsewhere.
Both of these types of skin cancer may develop as a flat area showing only slight changes
from normal skin.
Skin cancers other than melanoma, basal cell carcinoma, and squamous cell carcinoma
are much less common, and may look different.

• Kaposi sarcoma generally starts as small bruise-like areas that develop into reddish or
purplish tumors under the skin.
• Mycosis fungoides (a type of lymphoma that starts in the skin) usually begins as a
rash, often on the buttocks, hips, or lower abdomen. It can look like skin allergies and
other types of skin irritations.
• Adnexal tumors appear as bumps within the skin.
• Skin sarcomas appear as large masses under the skin surface.
• Merkel cell tumors are usually firm, pink, red, or purple nodules or ulcers (sores)
found on the face or, less often, the arms or legs.
If your doctor suspects you might have skin cancer, he or she will use one or more of the
following tests or exams.

Medical history and physical exam 
Usually the doctor's first step is to take your medical history (asking questions about
symptoms and risk factors). The doctor will ask when the mark on the skin first appeared
and whether it has changed in size or appearance. You may also be asked about past
exposures to possible causes of skin cancer (including past sunburns and tanning
practices) and whether you or anyone in your family has had skin cancer.
During the physical exam, the doctor will note the size, shape, color, and texture of the
area(s) in question, and whether there is bleeding or scaling. The rest of your body may
be checked for spots and moles that may be related to skin cancer.
The doctor may also check nearby lymph nodes, which are bean-sized collections of
immune system cells that can be felt under the skin in certain areas. Some skin cancers
may spread to lymph nodes. When this happens, the lymph nodes may become larger and
firmer than usual.
If you are being seen by your primary doctor and skin cancer is suspected, you may be
referred to a dermatologist (a doctor who specializes in skin diseases), who will look at
the area more closely.
Along with a standard physical exam, some dermatologists use a technique called
dermatoscopy (also known as dermoscopy, epiluminescence microscopy [ELM] or
surface microscopy) to see spots on the skin more clearly. The doctor uses a
dermatoscope, which is a special magnifying lens and light source held near the skin.
Sometimes a thin layer of oil is used with this instrument. A digital or photographic
image of the spot may be taken.
When used by an experienced dermatologist, this test can improve the accuracy of
finding skin cancers early. It can also often help reassure you that a lesion is likely benign
(non-cancerous) without the need for a biopsy.

Skin biopsy 
If the doctor thinks that a suspicious area might be skin cancer, he or she will take a
sample of skin from the area to be looked at under a microscope. This is called a skin
biopsy. If the biopsy removes the entire tumor, it is often enough to cure basal and
squamous cell skin cancers without further treatment.
Different methods can be used for a skin biopsy. The choice depends on the suspected
type of skin cancer, where it is on your body, the size of the affected area, and other
factors. Any biopsy is likely to leave at least a small scar. Different methods produce
different scars, so if you are concerned ask your doctor about possible scarring before the
biopsy is done.
Skin biopsies are done using a local anesthetic (numbing medicine), which is injected
into the area with a very small needle. You will likely feel a small prick and a little
stinging as the medicine is injected, but you should not feel any pain during the biopsy.
Shave biopsy 
A shave biopsy is one way to take a skin biopsy. After numbing the area with a local
anesthetic, the doctor shaves off the top layers of the skin (the epidermis and the most
superficial part of the dermis) with a surgical blade.
Punch biopsy 
A punch biopsy removes a deeper sample of skin. The doctor uses a tool that looks like a
tiny round cookie cutter. Once the skin is numbed with a local anesthetic, the doctor
rotates the punch biopsy tool on the surface of the skin until it cuts through all the layers
of the skin, including the dermis, epidermis, and the upper parts of the subcutis.

Incisional and excisional biopsies 
To examine a tumor that may have grown into deeper layers of the skin, the doctor may
use an incisional or excisional biopsy technique. After numbing the area with a local
anesthetic, a surgical knife is used to cut through the full thickness of skin. A wedge or
sliver of skin is removed for examination, and the edges of the wound are stitched
together.
An incisional biopsy removes only a portion of the tumor. An excisional biopsy removes
the entire tumor.
Examining the biopsy samples 
All skin biopsy samples are looked at under a microscope by a pathologist, a doctor
trained in the examination and diagnosis of tissue samples. Often, the sample is sent to a
dermatopathologist, a doctor who has special training in making diagnoses from skin
samples.

Lymph node biopsy 
In uncommon cases where skin cancer spreads, it usually goes first to nearby lymph
nodes, which are small, bean-shaped collections of immune cells. If your doctor feels
lymph nodes near the tumor that are too large and/or too firm, a lymph node biopsy may
be done to determine whether cancer has spread to them.
Fine needle aspiration biopsy 
A fine needle aspiration (FNA) biopsy uses a syringe with a thin, hollow needle to
remove very small tissue fragments. The needle is smaller than the needle used for a
blood test. A local anesthetic is sometimes used to numb the area first. This test rarely
causes much discomfort and does not leave a scar.
An FNA biopsy is not used to diagnose a suspicious skin tumor, but it may be used to
biopsy large lymph nodes near a skin cancer to find out if the cancer has spread to them.
FNA biopsies are not as invasive as some other types of biopsies, but they may not
always provide enough of a sample to find cancer cells.
Surgical (excisional) lymph node biopsy 
If the doctor still suspects spread of cancer to a lymph node after an FNA does not find
cancer, the lymph node will be removed by surgery and examined. This can often be
done in a doctor's office or outpatient surgical center using local anesthesia and will leave
a small scar.