Skin Biopsies

What are skin biopsies?

A skin biopsy is a diagnostic procedure that removes a small skin sample for testing. A dermatologist typically conducts a skin biopsy to diagnose illnesses such as skin cancer, skin infections, inflammatory rashes, or even atypical cases of psoriasis and eczema. A biopsy may also aid in diagnosing scalp disorders or nail pathologies.

Biopsies can allow us to make precise diagnoses, leading to targeted treatments for our patients. This ensures both accuracy and efficiency in managing skin health. Biopsies can also be utilised to monitor response to treatment.

The skin is made up of three layers, with each layer varying significantly in both its anatomies and functions:

• Epidermis: the epidermis is the outermost layer of the skin and acts as a barrier against environmental stressors. It is also responsible for water retention and protection against infection.
  The epidermis is mainly composed of keratinocytes, which undergo continuous cycling. Keratinocytes move from the lower layers (basal epidermis) to the top (stratum corneum), where they eventually shed off. The epidermis also contains melanocytes, which are pigment-producing cells that give skin its colour and protect against UV radiation.
• Dermis: the dermis is a thicker layer beneath the epidermis, giving the skin flexibility and strength. It is rich in collagen and elastin, which provide the scaffolding and support for this layer.
  This layer contains various structures, such as sweat glands, oil glands, hair follicles, nerve endings, and blood vessels.
• Hypodermis or subcutaneous fat layer: this is the deepest layer of the skin and consists of fat cells. It helps with insulation, regulates body temperature, and protects internal organs from external impact.

How do skin biopsies work?

There are four main types of skin biopsies:

• Punch biopsy: a punch biopsy requires a sharp and circular instrument. The instrument removes a small, round piece of full-thickness skin sample, providing valuable information about the architecture and pathology of the three layers of the skin. This can be used to diagnose inflammatory skin conditions or skin tumours. We can adjust the size of the skin biopsy to be typically between 2 mm to 6 mm. Sometimes, the size of a punch biopsy is selected to suit the size of the lesion being tested to remove the skin lesion and, at the same time, obtain a diagnosis.

• Shave biopsy: a shave biopsy is a procedure that removes a superficial layer of skin. It requires no stitching and typically lasts between 10 and 15 minutes. This technique can diagnose specific types of skin cancer, such as basal cell carcinoma or squamous cell carcinoma. It is also used to diagnose and remove superficial growths on the skin, such as viral warts or seborrhoeic keratoses.

• Excisional biopsy: an excisional biopsy is a surgical procedure that removes an entire lump or suspicious area. It is often done for suspicious moles, which need to be removed in entirety to examine the lesion as a whole. It is also done for lumps and bumps on the skin, such as dermatofibromas, epidermal cysts, and neurofibromas, all of which can be excised for diagnostic and curative purposes.

• Incisional biopsy: an incisional biopsy is indicated when we need to examine a specific area of a larger lesion where removing the entire lesion would be impractical. It is also utilised for deeper skin conditions where we suspect the pathology is deep in the hypodermis, e.g., medium vessel vasculitis and panniculitis.

What happens during skin biopsies?

The area is cleaned, and local anaesthesia is administered before the procedure.

Punch biopsy

• Step 1: a punch biopsy is positioned over the skin. The instrument then rotates to remove a small piece of tissue.
• Step 2: the sample is lifted from the skin and removed.
• Step 3: depending on the sample size, you may require two or three stitches to close the wound.
• Step 4: the wound is then covered with a waterproof bandage.

Shave biopsy

• Step 1: a scalpel scrapes or shaves a sample from the epidermis at the level of the skin.
• Step 2: once completed, electrocautery is performed to stop bleeding, and pressure is applied.
• Step 3: a bandage is placed over the wound to prevent risks of inflammation and infection.

Excisional or incisional biopsy

• Step 1: an elliptical incision is made around the part of the skin to be removed.
• Step 2: after the sample has been lifted, the wound is closed in layers with stitches.
• Step 3: a waterproof bandage will then be placed over the wound.

What conditions can skin biopsies diagnose?

Skin biopsies can aid in the diagnosis of various skin conditions, such as:

• Skin cancer or premalignant skin conditions
• Eczema
• Psoriasis
• Inflammatory dermatosis, such as autoimmune diseases or vasculitis
• Bacterial or fungal skin infections

Additionally, your dermatologist may encourage a skin biopsy if you have:

• Blistering skin
• Extensive or persistent rashes that do not respond to treatment
• Slow healing wounds
• Mole or skin growths that change in colour, size, or shape
• Mole or new skin growths that correspond to the ABCDEs of skin cancer

What can I expect after a skin biopsy?

Your comfort is our priority at Lumine Dermatology & Laser Clinic. Be rest assured that your skin will be attended to and treated with the utmost care.

Typically, after a skin biopsy, the area is covered with a discreet, skin-coloured, and waterproof bandage to protect it from infections and injury. Leave the bandage on for at least 24 hours. Thereafter, we will provide you with an antiseptic solution to clean the wound and an antibiotic ointment to apply.

Biopsy sites typically heal within 1 to 2 weeks. The wound will initially heal from the outside in and may look pink and slightly raised as new tissue forms. Over time, this area becomes less noticeable, though it may not completely disappear. Taking good care of your biopsy site and keeping your follow-up appointments are essential.

We will discuss the biopsy results as soon as they are available. This typically takes two weeks.

While you can go about your day normally, be sure to avoid the following:

• Swimming in a pool or the sea till the stitches are removed (typically between 1-2 weeks)
• High-intensity exercises that will exert extra tension on the wound (for 2 weeks)

Frequently asked questions

Are skin biopsies painful?

Generally, skin biopsies are quick, safe, and painless procedures performed under local anaesthesia. After the initial sting from the numbing injection, there should be no pain during the procedure. The area remains numb for about 4 hours post-surgery, and there is usually no need for oral painkillers afterwards.

How long do skin biopsies take?

The procedures typically take 15 minutes at most. The results, on the other hand, take an average of about two weeks to return. If additional tests, such as immunostaining, need to be done, this may prolong the turnaround time for the skin biopsies.

How often are skin biopsies cancerous?

The mean percentage of malignant skin biopsies is about 44%. However, most skin cancers are detected early enough to be treated with a high chance of a cure. Skin biopsies on suspicious moles performed by dermatologists trained in dermoscopy and skin cancer detection have been shown to give the lowest numbers needed to treat (NNT), which means the lowest rate of unnecessary biopsies to diagnose skin cancers among various healthcare professionals.

Does insurance cover skin biopsies ?

Yes, most skin biopsies are covered by insurance. Our Lumine Dermatology and Laser Clinic staff can assist you with this process.

How much does a skin biopsy cost?

At Lumine Dermatology and Laser Clinic, skin biopsies cost as follows:

• SGD350 (shave excision)
• SGD 500-600 (punch biopsy- depends on size and location)
• SGD1000- 1200 (excision biopsy- depends on size and location)

This will exclude the cost of histology testing, which typically ranges from SGD 250-300.