Melanoma: Clinical sciences

Melanoma is a very serious type of skin cancer arising from pigment-producing cells called melanocytes. It’s the fifth most common cancer in the United States and is associated with high rates of mortality. Melanoma can develop anywhere on the body and has a high rate of spread, so early diagnosis and treatment are key to improve overall outcomes.

Alright, when a patient presents with a chief concern suggesting melanoma, the first step is to obtain a focused history and physical. Typically, patients will report noticing a skin lesion with recent changes in size, color, or developing associated symptoms like pruritus. Sometimes they might even notice bleeding from the lesion.

A patient may also experience systemic symptoms that are alarming for malignancy, including fevers, chills, fatigue, bone pain, or weight loss. History might reveal risk factors like a personal or family history of cutaneous malignancy or immunosuppression, as well as fair skin, a tendency to sunburn, chronic sun exposure, or previous sunburns.

On a physical exam, you’ll typically find a pigmented skin lesion like a macule, plaque, or nodule with an irregular border. Make sure to do a full body exam checking for other similar lesions or nevi.

Important findings can be summarized by the mnemonic ABCDE, which stands for Asymmetry; Border irregularities; Color variations, such as brown or black spots with other colors like red, blue, gray, or white; Diameter, often larger than 6 mm; and Evolution, like changes in size, shape, or color, depigmentation, development of streaks, pseudopods or irregular vascularity.

Some of the suspicious characteristics you should look for include bleeding, crusting, or ulceration. If you see a lesion that differs from other nevi, it is called the "ugly duckling sign". Last but not least, remember to check regional lymph nodes for lymphadenopathy, which is concerning for possible metastasis. If you see these findings, be very suspicious of melanoma.

Here’s a clinical pearl! Primary care settings usually perform naked-eye physical examination, while dermatologic settings may also use support diagnostic tools like a dermatoscope, which acts as a magnifying glass to help evaluate the lesion in more detail.

The best way to confirm the diagnosis is with an excisional or incisional biopsy of the lesion, which will provide histopathological information. When possible, an excisional or complete biopsy should be performed to remove the entire lesion. This is done by taking 1 to 3 mm margin of surrounding normal skin, including the depth of the thickest part of the lesion. However, this might not be feasible if the lesion is large or located on the face, palms, or ears.

In these cases, incisional, or partial, biopsy can be performed. The important aspect of incisional biopsy is to ensure the full depth of the lesion is obtained within the sample, which is needed to determine the tumor depth.

Time for a clinical pearl! If you suspect melanoma, never obtain a shave biopsy, as it doesn’t obtain the full depth of the lesion, leading to inaccurate staging and inadequate treatment!

Okay, histopathology findings consistent with melanoma include atypical melanocytes with hyperchromatic nuclei, or other abnormal nuclei or nucleoli characteristics, in addition to asymmetric, poorly circumscribed nests of melanocytes. If findings aren’t consistent with melanoma, consider an alternative diagnosis; but if these findings are present, you can confirm your diagnosis of melanoma.

Here’s a clinical pearl! There are four main subtypes of melanoma. Superficial spreading melanoma is the most common one, accounting for 60% of cases, followed by nodular melanoma, which makes up 15 to 30% of cases. The last two types, lentigo maligna melanoma and acral lentiginous melanoma, are much less common. Other rare subtypes include amelanotic, dermoplastic, and spitzoid melanoma.

Now that you’ve made your diagnosis, your next step is to assess the Breslow thickness as well as ulceration. The Breslow thickness examines the lesion’s depth, meaning its vertical growth in millimeters from the most superficial aspect of the tumor, usually within the epidermis, down to the deepest layer. Depth, along with ulceration, are very important characteristics to help determine the appropriate treatment.