Cutaneous melanoma can appear anywhere on the skin surface. Melanoma can develop in a pre-existing mole, or arise on normal-appearing skin. It is suspected when a “mole” looks uneven in terms of its border, shape, or color. Diagnosis is confirmed with a simple skin biopsy, which is performed using one of several techniques. More information on the clinical appearance of skin abnormalities, including melanoma and other tumors or benign entities, can be found at www.dermatlas.org.
An excisional biopsy is the removal of an entire skin lesion with a tiny rim of normal-looking skin. It is a common method for collecting a skin sample to determine whether it is cancerous. This technique leaves a small scar.
A common way to sample a larger skin lesion is a punch biopsy. This technique uses a cylinder “punch” which cuts out a core of the thickest section of the lesion for testing.
For rare cases, where a melanoma is suspected in the nail bed, a long narrow excisional biopsy is preformed. In the case of oral or genital mucosal lesions, small biopsies should be performed just like skin lesions.
Fine-needle aspiration is not used for a primary melanoma site, but for a discrete lump of mass that could represent melanoma recurrence or melanoma in a lymph node, particularly in patients who already have a diagnosis of melanoma. In some circumstances, an ultrasound or computed tomography-guided fine needle aspiration may be appropriate if the area is best seen on imaging studies.
Understanding Your Pathology Report
For primary melanoma, one of the most important factors is tumor thickness, which is a surrogate for tumor volume. Tumor depth is the strongest prognostic indicator. The next factors that are additive risk indicators include ulceration over most of the tumor surface, rate of mitosis (cell division), presence of satellite tumor spread and nerve invasion.
At Johns Hopkins, our dermatopathologists accept slides to review prognosis. Our experts apply the full range of diagnostic tools in evaluating cases.