Malignant Melanoma

In keeping with our general theme for the summer months, we will continue with our review of skin cancers, in the hopes of providing the average clinician with a rapid fire, clinically relevant review of something we must be comfortable identifying.

Previously, we have covered both basal cell carcinoma and squamous cell carcinoma.

Today, we will cover the most dangerous, and usually most feared by patients, malignant melanoma.

Melanoma is perhaps most feared by patients because patients are aware that melanoma can be fatal. According to Swetter and Geller (2019), melanoma is the 5th most common incidence of type of cancer and in addition, Bryce and Snyder (2016) report that up to 2% of all cancer deaths are attributed to melanoma.

Melanoma is an integumentary system tumor arising the malignant transformation of the melanocyte. There are four main types of melanoma:

  1. Superficial spreading
  2. Acral lentiginous
  3. Nodular
  4. Lentigo maligna

 

Melanoma Epidemiology

Melanoma impacts Caucasian white males most commonly, age of onset is in the 5th to 6th decade of life, but melanoma is now being seen ealier due to lack of sunscreen use and increased use of tanning beds and total sun exposure.

Whites are impacted about 20 times that of dark skinned individuals (Bryce and Snyder, 2016).

The risk factors for melanoma are numerous and are similar to those for BCC and SCC. It is important to note that genetic technology has identified numerous mutations which can run in families, so family history is very important, with up to 12% of patients having a positive family history (Bryce and Snyder 2016).

 

Risk Factors

Other risk factors include UVA/UVB exposure, increased number and severity of previous sunburns, fair complexion, light skin, light eyes, blond/red hair, increased number of nevi, other history of skin cancer, family history, occupation, immunosuppression.

Tanning bed use is highly associated with skin cancer development, these are classified as a Class I carcinogenic by the World Health Organization.

The pathophysiology is multifactorial but stems mainly from DNA damage to the skin based on prolonged UVA/UVB exposure and previous history of sunburn contributes significantly to this.

The initial phase of growth may take months to years and is usually horizontal/lateral, meaning that the lesion will start to enlarge across more surface area of skin. Eventually, the tumor starts to grow vertically, which influences spread and potential for metastasis, growing down into the dermis and further skin layers.

The Breslow depth is a prognostic tool used by measuring the depth of the tumor. The larger the depth, the poorer prognosis and higher potential for metastasis when diagnosing melanoma.

As discussed in our previous articles related to skin cancer, prevention is extremely important.  Parents should be notified of the harms of frequent sunburns during childhood.  Patients should be educated on the use of sunscreen with SPF of at-least 30, re-applied every few hours, especially if sweating or going in the water.

Tanning beds must be avoided. Patients should be counseled to avoid sunlight during peak hours (usually 10 am to 4 pm). In my practice, I commonly discuss use of sunscreen at physicals and well exams because I have a great deal of patients whose occupation requires them to be outside, even in the hot summer months. We as clinicians should not simply assume our patients are wearing sunscreen, as many do not.

 

Understanding the Four Types of Melanoma

There are four main types of melanoma.

The first and most common is a superficial spreading melanoma, which accounts for up to 70% of melanomas. It is described as a pigmented macule or thin plaque and is commonly found on the back, extremities, and trunk. It may be described as a flat, irregularly bordered lesion.  It is pictured below:

superficial melanoma

The second most common type of melanoma is a nodular melanoma.

The incidence of nodular melanoma is estimated to be between 15 and 30% of melanomas. It is commonly thick and pigmented and may be a plaque or papule:

nodular melanoma

Lentigo maligna is another form of melanoma which usually occurs in elderly patients with sun damaged skin. Incidence is increasing due to a lack of sunscreen use and awareness regarding skin cancers. It tends to be slow growing and is seen on the head, neck, forearms.

lentigo melanoma

Acral lentiginous accounts for only 2 to 8 percent of melanomas (Bryce and Snyder 2016) but can commonly be missed due to its’ location. It is commonly seen in dark skinned patients on the palmar, plantar, and subungual areas. Subungual melanoma is a melanoma that is found under the nail bed. It can sometimes present as only a dark streak below the nail surface.

acral lentiginous melanoma

Acral lentiginous melanoma

Subungual melanoma

Subungual melanoma

 

 

Understanding the History of Melanoma

The method for identification of a melanoma or skin lesion that is of concern may come up in a variety of ways. Patients may come in with a specific concern about a mole that is changing or growing rapidly, a friend or hairdresser may have identified a lesion, or the clinician may identify a lesion during a physical exam or routine skin check.

When discussing a lesion with a patient, there are numerous questions that are very important to ask. I typically get 1 to 2 visits in primary care per week that are specifically for a skin lesion.

Our classic OPQRST is important, but we must also assess whether there is a personal or family history of melanoma. History of sun exposure, particularly severity, frequency, and duration are important, as well as immunosuppression and occupational exposure.

In addition, we must do a focused history on the specific lesion.

Depending on the location, the patient may not even be able to see the lesion, thus they may not know how long it has been present. For those that are visible, asking the patient how long it has been present is helpful.

I also find it is helpful to ask how long it has been concerning.

Changes in color must be questioned, in addition to a change in size, shape, and feeling. Bleeding, ulceration, and non-healing status are also helpful. Many times with basal and squamous cell carcinomas, patients will tell me that a razor or friction causes the lesion to fall off, but it comes back.

 

The Physical Exam

After the history, the physical exam is paramount for diagnosis and suspicion. In my practice, my typical simple question to myself is: “Am I worried about this lesion?”.

If the answer is yes, the proceeding is very simple: the patient needs a biopsy or excision. If no, then I am faced with many other questions, such as why am I not worried and what would make me worried?

Thankfully for clinicians and students, there is a mnemonic that most of you will be well acquainted with that can help determine whether a lesion is concerning or not. In my practice, I commonly educate patients about the ABCDE mnemonic in the hopes that they might be able to identify a lesion to be evaluated in the future:

  1. Asymmetry (lesions with asymmetric shapes are more concerning)
  2. Border- lesions with irregular borders, such as smooth on one side, then jagged, are more concerning as well.
  3. Color: brown tend to be benign, while black, red, purple, blue are concerning
  4. Diameter: Greater than 6 mm is more concerning (Larger than the size of a pencil eraser)
  5. Elevation/evolution: Is it raised? Has it grown, evolved, changed color, changed in feeling?

It is important to assure that the clinician does a full and thorough skin examination. In addition, the clinician should be sure to examine the palms, soles, between the fingers and toes, below the nail beds, and body areas covered by hair.

The term ugly duckling sign implies a mole or lesion that is vastly different from the patient’s typical moles and actually has some good predictive value for melanoma/skin cancer.

 

Who Needs a Biopsy?

As discussed within previous articles, the decision to biopsy is an important one and is determined by many factors. Any lesion that a primary care clinician is concerned about should be biopsied. Depending on the level of comfort, this can be accomplished in the office or an urgent referral can be made to a more experienced dermatologist or plastic surgeon.

The decision to perform punch biopsies, shave biopsies, elliptical excisions and other matters associated with the physical procedure of performing a biopsy go beyond the scope of this article and should be referenced elsewhere. 

Clinicians not comfortable with these techniques or for lesions on a cosmetic area (face, nose, ears, etc) should be sent to an experienced dermatologist.

Although suspicion may be very high based on exam, the gold standard for diagnosis is the biopsy. Once the biopsy has been made, an experienced pathologist can make the diagnosis, determine local tumor invasion, and determine whether negative borders have been achieved. It is important to note that if there is a specimen that does not have good borders, and the full lesion is not excised, wider excision will be needed. The level of margins around the lesion depends on stage and dermatologist experience.

 

Managing Melanoma (Staging)

As discussed above, the level of local invasion and thickness of the tumor (Breslow Depth) helps to determine the prognosis. Lesions caught early are very highly curable. According to their 2019 article (Swetter and Geller) on melanoma, the five stages are as follows:

  • Stage 0: In Situ
  • Stage 1+2: local cutaneous disease
  • Stage 3: Local or regional lymph node involvement
  • Stage 4: Distant metastasis.

Overall prognosis and 5 year survival drops significantly once metastasis has presented. Staging can also be performed via the TMN classification.

In stages I through III, surgical excision is usually curative, while Stage IV usually requires extensive chemotherapy.

Plastic surgery may be necessary based on area, location, and cosmetic result.

An experienced oncologist should be involved to dictate the chemotherapy regimen, prognosis, staging, and follow ups. CT scan, MRI, or PET CT may be necessary depending on staging and suspicion of metastasis. The full evaluation for chemotherapy use, choice, and follow up goes beyond the scope of today’s article and is reserved for the specialist.

I am hopeful that our review of skin cancers has provided you with some increased confidence and diagnostic skills for both the students and clinicians out there.

Remember, there are many risk factors for skin cancer and unfortunately skin cancer continues to be on the rise. Make sure your patients are respecting the sun and wearing sunscreen to avoid adding to the nation’s rising skin cancer incidence.

References

  • Bryce, Carl and Matthew Snyder (2016). Melanoma. The 5 minute clinical Consult. Wolters Kluwer.
  • Swetter, Susan and Geller, A.C. (2019). Melanoma: Clinical Features and Diagnosis. UpToDate. Date of Access 10 July 2019, 12 July 2019.
  • Swetter, Susan and Geller, A.C. (2019).Screening and early detection of melanoma in Adults and Adolescents. UpToDate. Date of Access 10 July 2019, 12 July 2019.