Skin Biopsy in Dermatology: Classification, Technique, and Diagnostic Value

A skin biopsy is an invasive diagnostic procedure in which a small tissue sample is removed for morphological evaluation. Depending on the clinical question, the specimen may include the epidermis, the dermis, and, when needed, subcutaneous fat. Skin biopsy provides a high diagnostic yield and, in some cases, remains the only way to establish a definitive diagnosis.

Microscopic examination of the biopsy specimen provides detailed information about cellular and tissue architecture, the presence of a pathologic process, the nature of a tumor, and the extent of tissue changes. In clinical practice, biopsy supports early diagnosis and helps guide timely management, reducing the risk of complications.

History and Development of PRP Therapy

Early descriptions of skin biopsy date to the 19th century, when microscopy began to be used to support and confirm clinical diagnoses.

In the 20th century, standardized biopsy techniques made specimen collection faster and more reproducible. Today, advances in histopathology and molecular diagnostics make it possible to obtain highly accurate results while minimizing tissue trauma.

Clinical Purpose and Indications for Skin Biopsy

• Diagnostic confirmation: to confirm or refine a clinical diagnosis.
• Differential diagnosis: to distinguish between clinically similar dermatoses.
• Cancer detection: to identify malignant and premalignant condition.
• Staging and activity assessment: to evaluate disease stage and activity.
• Treatment monitoring: to assess response to therapy.

Classification

In current dermatologic practice, skin biopsy can be classified in several ways.

By the amount of tissue removed

• Excisional skin biopsy: complete removal of a lesion, typically with a margin of clinically normal tissue.
• Incisional skin biopsy: removal of a portion of a lesion within the pathologic focus.

By the method of tissue sampling

• Punch biopsy,
• Shave biopsy (superficial shave, razor technique),
• Trephine biopsy,
• Wedge biopsy.

Technique and Indications for Common Biopsy Types

In most cases, no special preparation is required. The procedure typically takes 15 to 20 minutes and is performed in a procedure room or operating room. Before sampling, the clinician performs antiseptic skin preparation and administers local anesthesia. The biopsy technique is selected based on the lesion’s morphology, size, and anatomic location.

Antiseptic skin preparation

Local anesthesia

Biopsy depth should match the suspected diagnosis and the goals of histologic evaluation. For superficial inflammatory processes, sampling may be limited to the dermis. For deep infiltrative processes, the specimen should include subcutaneous fat, as key diagnostic changes may be present below the dermis.

Punch Biopsy

Rotating the biopsy punch

Grasping and removing the specimen

A sterile, single-use biopsy punch is positioned perpendicular to the skin surface and advanced with a rotating motion to the level of the subcutaneous fat. The tissue cylinder is gently lifted with forceps and transected at the base using scissors or a scalpel. If needed, one or two interrupted sutures are placed. The site is then covered with a sterile dressing.

Punch biopsy is widely used for inflammatory, non-neoplastic skin disorders and for evaluation of vasculitis. It allows sampling across skin layers with minimal tissue disruption when performed correctly.

Shave Biopsy (Superficial Shave, Razor Technique)

The lesion is removed parallel to the skin surface using a disposable razor or blade. The sample is superficial and typically does not include the deep dermis. Sutures are usually unnecessary, and the wound is covered with a sterile dressing.

Shave biopsy is most often used for pedunculated lesions, papules, and other raised growths, including seborrheic keratoses and warts. For most inflammatory dermatoses, this technique is less informative because it may not capture the depth needed for diagnosis.

Excisional Skin Biopsy

After antiseptic skin preparation and local anesthesia, an elliptical incision is made with a scalpel. The lesion is removed in full thickness, including subcutaneous fat, with margins extending into clinically normal tissue when appropriate for diagnostic evaluation. After hemostasis is achieved, the wound is closed with simple interrupted or subcuticular sutures, and a sterile dressing is applied.

Excisional biopsy is indicated when benign or malignant neoplasms are suspected, including papillomas, warts, seborrheic and actinic keratoses, pyogenic granulomas, and rhinophyma. It may also be used to remove hypertrophic scars or scars of cosmetic concern.

Specimen Handling, Fixation, and Transport

Placing the specimen in fixative

Histopathologic evaluation

Immediately after sampling, the specimen is placed in a fixative, most commonly 10% neutral buffered formalin. The pathology request form should include essential clinical details, such as lesion location, duration, clinical appearance, relevant history, and the clinician’s differential diagnosis. Clear clinical context improves the accuracy and clinical relevance of the pathologist’s report.

Depending on the clinical indication, the specimen may be submitted for:

• Histological examination;
• Immunohistochemistry (IHC);
• Direct and indirect immunofluorescence (DIF/IIF);
• Molecular genetic testing.

Indications for Skin Biopsy

• Suspected malignant skin neoplasms;
• Inflammatory dermatoses of unclear etiology;
• Bullous disorders and autoimmune skin diseases;
• Chronic ulcers and infiltrative lesions;
• Skin infections with atypical presentation or course.

Contraindications

• Severe coagulation disorders,
• Acute purulent infection at the planned biopsy site,
• Severe overall patient condition that makes the procedure unsafe.

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Complications and Limitations

Complications after skin biopsy are rare. When they do occur, pain is the most common. Bleeding, keloid formation, and infection are less frequent.

Although skin biopsy is highly valuable, it has practical limitations and requires clinical expertise. An incorrect method, suboptimal site selection, or insufficient depth can result in a non-diagnostic specimen.