Simple cases

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Case 30

35-year-old woman with a pigmented skin lesion


Totally irrelevant; no hint of allergic contact dermatitis here.

Yes, the pale area at the border seems to have expanded.

Good question. The ABCDE rule is used to assess melanocytic nevi. E stands for “enlarging”.

Back then, no one paid much attention to sunscreens. I got burned at the start of every summer.

Reasonable question. Sun exposure is correlated with the number of melanocytic nevi and severe sunburns in children appear to lead to an increased risk of malignant melanoma.

I am in financial planning at a bank.

Occupational sun exposure also plays a role, although not in this case.


Good question. Patients with a melanoma have a significant risk of developing a second tumor.


There are some families with an increased risk of melanoma. Examples include mutations in CDKN2A on chromosome 9p (autosomal dominant), dysplastic nevus syndrome (site unclear) and xeroderma pigmentosum.


Could be helpful. Patients who are immunosuppressed also develop more melanomas. If excision is planned, one has to know about anticoagulants.

Choose the right efflorescences:

The lesion has a flat or macular component at the periphery.

There is no evidence of a localized thickening of the stratum corneum.

Poikiloderma features atrophy, telangiectases, and pigmentary changes. None are seen here, except for a single pigmented lesion.

There is a papule, as the lesion is raised and palpable.

Choose the right diagnosis:

Dermatofibromas can be pigmented but they can usually be easily distinguished from melanocytic nevi. They are firm, dimple with lateral pressure (Fitzpatrick sign), and show central fibrosis on dermatoscopy.

Seborrheic keratoses are also dark, but look waxy, warty and as if they could be easily scraped away. They have horn pearls and pseudofollicular openings on dermatoscopy.

A café-au-lait macule is flat, and under the microscope has primarily an increase in melan in, rather than in melanocytes.

Melanocytic nevi (or nevus cell nevi) are benign proliferations of melanocytes. Under the microscope, both single cells and nests of melanocytes are seen. Melanocytic nevi are divided into junctional, compound and dermal variants, depending on the histologic location of the melanocytes.

Choose the right therapy(ies):

The main disadvantage to laser destruction is that no specimen is available for histology, in order to exclude a malignant melanoma.

The clinical and dermatoscopic examination both suggest this lesion is benign, so no treatment is needed.

Excision is not mandatory. If any questions exist or if the patient wants the lesion removed for cosmetic reasons, then this is the preferred approach.

It is unwise to curette melanocytic lesions. Usually some nests are left behind in the dermis and they can lead to bizarre clinical recurrences (pseudomelanoma).

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