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. As other doctors from different specialties, other than dermatologist, are also consulted when discussing diagnostic findings of 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

Basalioma or basal-cell carcinoma is the most common neoplasm of the skin. It forms the novo emanating from basal cells, which means it is 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 and people having brighter skin color are particularly threatened. Arsenic-exposure may as well lead to malignant degeneration of basal cells.

Characteristic of basalioma is the fact, that it almost never metastasizes; however, it distructs and grows locally, 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 nodular basalioma, which is characterized by a single or multiple central nodules having a string-of-pearls margin and telangiectasias (small dilated blood vessels). Other types are superficial (situated on skin level), sclerosing and 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. Adequate safety margins are obtained and a successive histological follow-up of the cutting edges is performed. In areas where extensive excision is impossible due to aesthetic reasons (i.e. the face), the tumor should 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 alternative treatments for non-resectable basaliomas.

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

Notes 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 is the therapy of choice, yearly check-ups

Malignant Melanoma – Silent and Spreading

Not the most common, but the most feared type of skin cancer involves malignant degeneration of melanocytes – the malignant melanoma. It accounts for over 90 % of deaths caused by skin cancer. Chronic UV-light exposure, damages caused by sun light including 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.

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

Malignant melanoma on the chest

Image: „This image depicts a patient’s chest, which displays numerous dark-pigmented cutaneous lesions, which were 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 malignant melanoma: The most common type is the superficial spreading melanoma (60 %), which first grows in width and later on in depth. 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

Lentigo maligna melanoma (10 %) is a common melanoma found in old people. Its causal reason is 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). The liver, skeleton and brain are among other locations where distant metastases are commonly found.

The ABCDE-mnemonic is a popular method for early detection of melanomas. Nevi which meet one or more of the following criterions should undergo further evaluation 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 a dermatoscopy confirms a primary tumor, a complete surgical excision with adequate surgical margins (0,5cm) is performed whereupon the excisional skin undergoes a subsequent histopathological examination. In case of 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 that 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 TNM-classification.
 After histological analysis of a malignant melanoma is completed, clinical staging should follow, whose extent is determined by histopathological findings. It includes 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 for malignant melanoma is surgical excision. Adjuvant therapy does not yield higher survival rates. However, patients in progressed tumor stages may benefit from 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 has been accredited since 2011. Ipilimumab reinforces the body’s own immune reaction against tumor cells by blocking their receptors, which induces a down-regulation 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.

Notes regarding melanoma:

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