Cutaneous Tumors, Dermoscopy, and Dermatopathology Correlation
Pattern, then proof
Tumor questions test whether you can separate benign from malignant by history, dermoscopy, and histology, and whether you know the management implication of each diagnosis.
Concepts to master
- Basal cell carcinoma: pearly papule with telangiectasia, rolled border, ulceration; dermoscopy shows arborizing vessels and blue-gray ovoid nests. Rarely metastasizes but is locally destructive.
- Squamous cell carcinoma: hyperkeratotic, ulcerated, or crusted lesion on sun-damaged skin; risk of metastasis is higher than BCC.
- Melanoma: asymmetry, border irregularity, color variation, diameter, and evolution; dermoscopy shows atypical network, irregular dots and globules, regression, and blue-white veil. Breslow thickness drives prognosis.
- Benign mimics: seborrheic keratosis (stuck-on, comedo-like openings), dermatofibroma (dimple sign), pyogenic granuloma (friable, bleeds easily).
- Adnexal and vascular tumors: know the common ones and their benign versus malignant behavior.
Traps
The commonest trap is diagnosing melanoma by the ABCDE criteria alone while ignoring dermoscopic pattern and change over time. Another is treating a pigmented lesion as benign because it is small - small melanomas exist. Also remember that biopsy technique matters: an excisional biopsy with narrow margins is preferred for suspected melanoma, not a shave.
Worked example
A pigmented lesion with an atypical network and irregular globules on dermoscopy. The correct next step is a full-thickness excisional biopsy, not cryotherapy or observation. Histology then determines Breslow thickness and margin requirements.