Skin biopsy techniques

Skin biopsy techniques 

 

Types 

1. Shave biopsy 

2. Punch biopsy

3. Incisional biopsy

4. Excisional biopsy  

 Steps common to all minor procedures

 

SHAVE BIOPSY 

1. Stabilize the lesion between the thumb and forefinger in a direction perpendicular to Resting skin tension lines

2. A vertical cut is put at the periphery of the lesion using 11 or 15 No. scalpel blade attached to No. 3 BP handle

3. Blade is held parallel to the skin surface and then passed through the lesion through the cut that is already made at the periphery 

4. The blade is advanced through the lesion by a smooth sweeping stroke rather than a sawing motion while grasping the lesion with forceps

5. Hemostasis is achieved by firm pressure or with the chemicals
   

6. The procedure can also be performed by using halved razor blade or curved scissors.

7. Antibiotic cream applied and a gauze dressing is given

 

 

PUNCH BIOPSY  

1. Routinely a 3-4 mm punch is chosen

2. Traction given in a direction perpendicular to long axis of resting skin tension lines  

3. Punch is held vertically, and a steady pressure is applied

4. Punch is rotated in a clockwise manner till the punch reaches the subcutis. At this stage there is feeling of give away

5. Punch is withdrawn

6. Tissue cast is lifted with fine forceps while avoiding crushing and damage to epidermis. It is then cut at the base with scalpel blade as shown in figure

7. On releasing the tension, the circular biopsy defect relaxes into ellipse

8. The wound may be sutured for better healing with interrupted sutures for cosmetically important regions, but otherwise only dressing is generally done

 

PRACTICAL TIPS AND TRICKS: 

 Approximately, ½ of the blade of skin punch should be visible when it reaches the subcutis. 

 

  

INCISIONAL BIOPSY 

1. In this type, biopsy is performed from active edge of the lesion in a wedge shape including the normal skin. Alternatively, it can be performed by using biopsy punches of size 5 mm and above 

2. Area is kept taut and scalpel with No. 15 blade is held like a pencil

3. Begin the incision at the apex holding the blade perpendicular to the skin 

4. As the incision progresses blade is angled to 45° to cut the tissue with the belly of the blade

5. At the end of the incision again the scalpel is lifted vertically to prevent the excision from extending beyond the end point 

6. Wedge of tissue separated from underlying tissue with scalpel or dissecting forceps

7. Interrupted suture taken for larger and deeper defects suturing is done in two layers

 

 

EXCISIONAL BIOPSY Different techniques are been used to excise lumps from different parts of the body and different types of the lump. Separate document for the same has been sent.

 

Written by our guest authors Mohit Jain and Kritika Bhatia

Illustration by Devi Bavishi
#Ae(ONE)INTERN