Neoplasms of the skin can be hard to differentiate clinically, but nevertheless they can result in entirely different consequences. While the colloquially called “white skin cancer” describes rather harmless changes of the skin, the “black skin” cancer is feared. Since future doctors of specialties other than dermatology are also confronted with diagnostic findings on their patients’ skins, it pays off to know the most common types of skin cancer.
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solarium can cause skin cancer

Image: “Vitamin D Fix” by Evil Erin. License: CC BY 2.0

Basal-Cell Carcinoma – Aggressive and Local

Basal-cell carcinoma

Image: „Basal-cell carcinoma on the cheek“ by Josef Wienand. License: CC BY-SA 3.0

The basalioma or basal-cell carcinoma is the most common neoplasm of the skin. It forms the novo emanating from basal cells, which means not based on a precancerous condition. Basaliomas solely affect haired skin and usually appear in areas that are exposed to sun light. The most common localization is the face: about 80 % of all basaliomas appear on the connecting line between the corner of the mouth and the earlobe.

Mutations, which are evoked by years or decades of chronic UV-exposure, are causal for the formation of basaliomas, whereas people having brighter skin color are particularly threatened. Arsenic-exposure may as well lead to a malignant degeneration of basal cells.

Characteristic for the basalioma is the fact, that it almost never metastasizes, however grows locally destructing, and is able to induce significant damage to the surrounding tissue this way.

Nodular Basal cell carcinoma in 75-year-old man

Image: „Nodular Basal cell carcinoma in 75-year-old man.“ by Klaus D. Peter. License: CC BY 3.0 DE

Encountering morphologic features, there are various types of the basalioma. Quite common is the nodular basalioma, which is characterized by one or multiple central nodules with a string-of-pearls margin and telangiectasias (small dilated blood vessels). Other types are the superficial (situated on skin level), the sclerosing and the ulcerative basalioma.

High magnification micrograph of a basal cell carcinoma

Image: „High magnification micrograph of a basal cell carcinoma. H&E stain.“ by Nephron. License: CC BY-SA 3.0

Gold standard in therapy, subsequent to clinical and histological confirmation of the diagnosis, is the surgical excision of the tumor while adequate safety margins are obtained and a successive histological follow-up check of the cutting edges is performed. In areas where extensive excision is impossible due to aesthetic reasons (i.e. the face), the tumor will be excised under constant intraoperative examination of the margins of resection (so-called micrographic controlled excision).

Superficial tumors alternatively may be treated with cryotherapy, photodynamic therapy or local chemotherapy. In cases of inoperable basaliomas radiotherapy is the treatment of choice. Furthermore hedgehog-inhibitors were admitted in 2013 as an alternative treatment for non-resectable basaliomas.

After curative therapy has taken place, periodic (yearly) follow-ups are suggested, since there is a higher risk for the event of further primary tumors.

Note regarding basalioma:

  • Almost no metastasis, local infiltration of the surrounding tissue
  • The face is the most common localization.
  • String-of-pearls margin and telangiectasias
  • Micrographic controlled surgery as the therapy of choice, yearly follow-up checks

Malignant Melanoma – Silent and Spreading

Not the most common but the most feared is the malignant degeneration of melanocytes – the malignant melanoma. It accounts for over 90 % of the cases of death caused by skin cancer. Chronic UV-light exposure, damages caused by sun light as far as sunburns (especially during childhood and adolescence), bright (Celtic) skin type and cumulative appearance of melanocytic nevi (> 100) or the presence of dysplastic nevi represent significant risk factors.

The malignant melanoma also – unlike the basalioma – appears often on areas of the body that are not exposed to sun light. A noticeable fact is that women more likely get affected on their upper thighs, whereas men rather get a malignant melanoma on their upper body.

Malignant melanoma on the chest

Image: „This image depicts a patient’s chest, which displays numerous darkly-pigmented cutaneous lesions, which had been diagnosed as malignant melanoma (MM).“ by CDC/ Carl Washington, M.D., Emory Univ. School of Medicine; Mona Saraiya, MD, MPH. License: Public Domain

Considering morphological and histological aspects there are 4 types of the malignant melanoma: The most common type is the superficial spreading melanoma (60 %), which first grows in width and later on into depth. The nodular melanoma (20 %) impresses with its nodular growth and primarily tends to grow in depth, which is why it has a worse prognosis.

Lentigo maligna melanoma

Image: „Irregular patch about 10mm square after scrape biopsy which concluded „suspicious of early malignant melanoma“. Post excision pathology was „Lentigo maligna – Melanoma in situ“. Colour before scrape biopsy was light brown.“ by Phanly. License: CC BY-SA 3.0

The lentigo maligna melanoma (10 %) is a common melanoma found in old people. Its causal reason is a hyperpigmentation (lentigo senilis) and they tend to present widespread and initially grow horizontally before growing in thickness (good prognosis).

Acral lentiginous melanomas (5 %) also grow horizontally at first and are usually found in the area of the palm of the hand, the soles of feet or around the affected person’s fingernails. The Hutchinson’s sign, which refers to a spread onto the periungual skin, is a characteristic clinical sign.

Metastasis of the malignant melanoma is either effected by lymphatic or by hematogenous spread. As a consequence of loco-regional spread metastases can appear on the patient’s skin (satellite metastases). Among numerous other organs, skin, liver, skeleton and brain are locations where distant metastases are commonly found.

The ABCDE-mnemonic is a popular method for the early detection of melanomas. Nevi which meet one or more of the following criterions should undergo further evaluation by using a reflected-light microscope (dermatoscopy).

  • A (asymmetry) = asymmetrical shape
  • B (border) = irregular margin and indistinct border
  • C (color) = varying pigmentation
  • D (diameter) = above 5 mm
  • E (elevated, enlarging) = convexness and rapid increase in size

If dermatoscopy approves a primary suspect of a tumor, a complete surgical excision with adequate surgical margins (0,5cm) is performed whereupon the excisional skin undergoes a subsequent histopathological examination. In the case of a histological confirmation of a malignant tumor, skin margins must be resected depending on the tumor’s thickness (see below) and depth of tumor invasion: A melanoma-in-situ (tumor does not penetrate the basal lamina) has to be removed including a safety margin of 0,5 cm (so no resection is necessary). For a melanoma which has grown across the basal lamina, the following safety margins apply (according to the S3-guideline):

  • tumor thickness < 1-2 mm: 1 cm
  • tumor thickness > 2 mm to 4 mm: 2 cm
Note: Breslow’s depth is defined as the histologically determined depth of infiltration in mm, starting from the granular layer of the epidermis. It is a determining criterion for the prognosis of the melanoma and defines the T-stage of the TNM-classification.

After histological analysis of a malignant melanoma is finished, clinical staging should follow, whose extent is determined by the histopathological findings. It includes i.e. the search for lymph node metastases using lymph node sonography, a chest X-ray in two planes, an abdominal sonography and a skeletal scintigraphy. For the exclusion of distant metastases a whole-body CT and MRI should be considered.

Therapy of choice of the malignant melanoma is surgical excision. An adjuvant therapy does not yield higher survival rates. However, patients in progressed tumor stages may benefit from an adjuvant immunotherapy using interferon-alpha.

Present metastases are to be treated using adequate methods (i.e. surgical resection, radiotherapy).

The latest greatest innovation in the therapy of melanoma is immunomodulation. The monoclonal antibody Ipilimumab is accredited since 2011. Ipilimumab reinforces the body’s own immune reaction against tumor cells by blocking their receptors, which induces a downregulation of the immune response. This way, a tolerance, which the body establishes against the growing tumor cells, is impaired. A similar mechanism is used by the PD1-inhibitor Nivulomab. According to current data (ongoing trials) the combination of Nivolumab and Ipilimumab seems to be promising, but also shows significant side effects.

Note regarding melanoma:

  • Early lymphogeneous spreading
  • Most commonly located on women’s thighs or on men’s torso.
  • ABCDE-mnemonic helps in early recognition.
  • T-stage is defined by Breslow’s depth.
  • Excision is therapy of choice, safety margin is depending on the tumor’s depth.
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