Types of Skin Lesions
Skin lesions can be broadly categorized as benign, premalignant, or malignant, with specific diagnostic characteristics that help differentiate them for appropriate management. 1
Primary Categories of Skin Lesions
Pigmented Lesions
- Melanocytic lesions include benign nevi and melanoma, which can be distinguished using the ABCDE criteria (Asymmetry, Border irregularity, Color variation, Diameter >6mm, Evolution) 2
- Non-melanocytic pigmented lesions include seborrheic keratoses, pigmented basal cell carcinomas, and hematomas 1
- Melanoma can be phenotypically diverse and may be mimicked by various benign lesions, making careful assessment critical 1
Inflammatory and Infectious Lesions
- Lichen sclerosus presents with thinned epidermis, hyperkeratosis, and lymphocytic infiltrate 1
- Furuncles are infections of hair follicles typically caused by S. aureus, while carbuncles involve multiple adjacent follicles 1
Nodular Lesions
- Cutaneous abscesses contain pus within deeper skin tissues, while epidermoid cysts contain keratinous material 1
- Keratoacanthomas can simulate squamous cell carcinoma but have distinctive features allowing differentiation 3
Premalignant Lesions
- Actinic (solar) keratoses are precursors to squamous cell carcinoma that can be treated with topical fluorouracil applied twice daily for 2-4 weeks until reaching the erosion stage 4
- These lesions typically appear on sun-exposed areas and require early intervention to prevent malignant transformation 5
Diagnostic Approach
Clinical Assessment
- Lesions that are growing, spreading, pigmented, or occur on exposed skin areas warrant particular concern 5
- For pigmented lesions, the ABCDE criteria help identify potential melanomas:
- A: Asymmetry
- B: Irregular borders
- C: Heterogeneous color
- D: Large diameter
- E: Evolution (recent change) 2
Advanced Diagnostic Techniques
- Epiluminescence microscopy (dermatoscopy) can improve clinical diagnosis by differentiating melanocytic from non-melanocytic pigmented lesions, though its accuracy depends on the examiner's experience 2
- Complete excision rather than partial biopsy is recommended for suspected malignant melanocytic lesions to allow full histological assessment 2
Management Considerations
Surgical Approach
- For melanocytic lesions suspected to be malignant, complete excision with a 2mm margin of normal skin is standard practice 2
- Incisions should be elliptical with the long axis parallel to skin lines for optimal cosmetic results 2
- Tissue should be removed using a scalpel rather than laser or electrocautery to preserve histological features 6
Medical Treatment
- For superficial basal cell carcinomas, 5% fluorouracil cream applied twice daily for 3-6 weeks (up to 10-12 weeks) is recommended until lesions are obliterated 4
- Complete healing may not be evident for 1-2 months following cessation of therapy 4
Histopathological Examination
- All excised tissue must be sent for histopathological examination to confirm diagnosis and assess margins 2
- The histopathological report for melanocytic lesions should include tumor thickness, completeness of excision, level of invasion, and presence of regression or ulceration 2
Special Considerations
Systemic Disease Associations
- Some skin lesions may indicate internal malignancies, such as acanthosis nigricans and dermatomyositis 7
- In patients under 3 years of age with characteristic skin lesions, consider Letterer-Siwe disease (with maculopapular and erosive lesions in seborrheic distribution) or neuroblastoma (with bluish papulonodules) 8
Common Pitfalls
- Several benign lesions can mimic malignancy, including desmoplastic trichoepithelioma, sclerosing hemangioma, and pigmented spindle cell nevus 3
- Avoid tissue destruction techniques for undiagnosed lesions as this compromises histological assessment 2
- Never rely solely on clinical appearance for definitive diagnosis of concerning lesions - biopsy is essential 5