Nodule development, with or without bleeding, signifies invasion and conversion to lentigo maligna melanoma. Patients should undergo regular follow-up examinations for signs of conversion to melanoma. Some authorities suggest cryotherapy or argon laser therapy to decrease the number of abnormal melanocytes and thus, theoretically, to reduce the risk of developing melanoma. However, both of these procedures have a high recurrence rate. Because conversion to melanoma is usually relatively slow, the decision to excise lentigo maligna should be based on several factors, including the size and location of the lesion, which determines the complexity of the procedure required, and the patient's life expectancy and comorbidities.
Diagnosis is confirmed by biopsy.
In general, shave biopsy is adequate for suspected basal and squamous cell carcinomas, whereas excisional biopsy is recommended for pigmented lesions suspected of being melanomas. A pearly papule that if neglected may evolve into a superficial ulcer, derived from epidermal basal cells, that is generally slow-growing and rarely metastasizes. As the lesion enlarges, it may develop central ulceration, creating the classic rodent ulcer. All basal cell carcinomas should be confirmed histologically by biopsy, preferably before starting therapy. Shave biopsy is usually preferred.