1. The Skin Biopsy

2. In no other field of medicine is tissue for histologic examination so easily accessible. As a result, the skin biopsy has become an integralcomponent of dermatologic diagnoses

3. Skin biopsies are performed for a multitude of reasons, including: uncertainty about the clinical diagnosis to investigate a poor response to therapy to exclude or investigate the evolution of one condition into another to investigate symptoms in the absence of clinically recognizable disease.

4. the process of securing appropriate tissue involves more than the mere mechanical removal of a specimen

5. Pitfalls of Skin Biopsy: Inappropriate Site SelectionInappropriate Biopsy TechniqueInappropriate Tissue Handeling

6. Site Selection: First step : Identify an unadulterated primary lesion (Exclude lesions with secondary changes) Second Step: choose Well developed but Fresh Lesion (It show the most characteristic and diagnostic histopathology ( Except : LCV)

8. Site Selection: 3rd Step: Obtain from central aspect of a primary lesion (except ulcer or subtle change as anetoderma) 4 th Step: selection of a proper biopsy site may also be influenced by knowledge of the underlying pathology and pathophysiology of the most likely diagnoses.

9. Biopsy techniques: Superficial (tangential shave) deep shave (saucerization) punch incisional/excisional

11. the technique: 1-must obtain tissue from the level of the skin or subcutaneous tissue where the pathologic changes are expected 2- simultaneously balancing concerns of cosmesis and morbidity.

12. Panniculitis: Do not perform shave biopsy Verruca or Skin Tag: Do not perform Excision

14. Curettage a curette 3-5 mm in diameter is held like a pencil and drawn with pressure under the lesion (if epidermal) or through the lesion (e.g. presumed BCC). This type of biopsy assumes that healing will be by second intention. The resulting scar is usually minimal

17. Shave Biopsy: Perform when: 1-the pathologic process is primarily epidermal 2- when removing exophytic benign lesions E.g. intradermal melanocytic nevi or pigmented actinic keratosis or Bowen's disease versus macular seborrheic keratosis )

19. Deep shave/saucerization biopsy Deeper variant of the superficial shave biopsy Often used to biopsy neoplasms (e.g. SCC versus hypertrophic AK) when properly performed, its diagnostic value is nearly equal to most incisional/excisional procedures

21. Punch biopsy: Perform when suspected pathology is within the dermis and when a partial sampling will be representative of the entire lesion or process.

22. Punch Biopsy: Poor Results: assessment of deeply infiltrating tumors or the full thickness of the subcutaneous fat. Partial punch biopsies of melanocytic neoplasms can lead to erroneous diagnoses.

26. Incisional /excisionalbiopsy Incisional: removal of a portion of a lesion (e.g. Panniculitis) Excisional: Removal of the entire lesion via a scalpel and standard surgical techniques (e.g. Melanoma)

33. Post-procedure handling of the biopsy Avoid crush artifact especially for small punch biopsy. Lymphocytes are particularly susceptible to crush artifact, and when present, it may be impossible to render an accurate diagnosis.

34. For routine histologic exam: place the specimen in the formalin container (volume 10x to 20x) Microbial culture: place in the non- bacteriostatic saline container and deliver immediately to LAB. For DIF: Flash Frozen or use Michel Solution

35. Other Information: Age and sex of the patient Anatomic site Pertinent and precise physical findings Differential diagnosis Treatments Drawings or clinical photographs