Warning signs of skin cancer

by Verónica Ruiz


Although the incidence of skin cancer has progressively increased over the last century, fortunately its detection is carried out earlier and earlier, thus improving the global prognosis of the disease. This fact has undoubtedly been favored by the skin cancer prevention campaigns that have been carried out in many countries over the last decades.

When should you consult your dermatologist

1. Suspected non-melanoma skin cancer: 

    You should suspect the presence of NMSC when you encounter the following warning signs:

  • Raise or appearance of new lump
  • Appearance of a scab or peeling
  • Appearance of a small ulcer or skin erosion (with probable associated bleeding)

All these changes appear fundamentally in skins or areas that have been exposed to the sun (photo exposed areas) and do not disappear for various months, it even progressively increases in size.

The tools that dermatologists have at our disposal to diagnose non-melanoma skin cancer have not changed much in recent years. 

Although, since a few years, we have some useful technology tools like dermoscopy, which can help us in the diagnosis of a certain injury suspected of malignancy, the realization of a good clinic inspection and taking of a confirmatory biopsy if necessary, it is still essential for the diagnosis of this type of skin injuries.

“Clinical inspection is essential for the early detection and management of skin cancer”.


2. Suspected melanoma:

Unlike NMSC, the diagnosis and treatment of melanoma has evolved significantly in the last century.

In the first place, it has improved the recognition of the clinical characteristics of melanoma in early stages by dermatologists and the awareness of patients regarding the consultation of suspicious injuries and the performance of skin self-examinations.

Secondly, a series of technologies have been developed, suh as a digital dermoscopy and confocal microscopy among others, which have helped to improve the precision in the early detection of melanoma, beyond simple clinical inspection.

The prognosis of melanoma is directly proportional to the thickness of the tumor, hence the importance of its early detection to reduce the incidence of advanced cases and mortality from this type of tumor.

What to look for

The system ABCDE is a set of parameters that can serve as a useful guide, for patients and doctors, to help detect some atypical characteristics that could be suspicious in a pigmented skin injury and, in this way, it would allow to diagnose melanoma in early stages.

You should consult with your dermatologist when you observe the following changes:

  • A Asymmetry. If we draw a dividing line in the center of the injury, the 2 halves do not coincide.
  • B Border Irregularity. The borders are irregular and are not well defined.
  • C Colour Variations. There is one or more colours in the same injury. The most frequent ones are black, Brown and toasted. The least frequent ones are red, white and blue.
  • D Diameter. The majority of melanomas in early stages measure > 6 mm.
  • E Evolving. The injuries are being modified, they shape, are changing shape, colour, size, consistency.

In addition to the ABCDE system, other useful and effective scales have been developed, such as the Glasgow 7-point scale, which was also developed to improve early recognition of melanoma but is less widely implemented in clinical practice.

Other changes in moles (nevus) that may indicate malignancy and that, therefore, dermatologists recommend reviewing are:

  • Recent appearance of new moles
  • Growth of a lump or rise within a nevus
  • Nevus whose surface becomes rough
  • Nevi that itch or bleed
  • Nevus that is different from others around you

In selected cases, such as the presence of multiple nevi, it is recommended to monitor them, using the image-registration technique that allows taking pictures of the different injuries and detecting possible changes in them early.

In our team, Dr Dalmau is the reference specialist in Melanoma and digital dermoscopy monitoring of melanocytic lesions.


  • Rogers HW, Weinstock MA, Feldman SR, et al. Incidence estimate of nonmelanoma skin cancer (keratinocyte carcinomas) in US population, 2012. JAMA Dermatol 2015;151(10):1081–6.
  • Tripp MK, Watson M, Balk SJ, et al. State of the science on prevention and screening to reduce melanoma incidence and mortality: the time is now. CA Cancer J Clin 2016. http://dx.doi.org/10.3322/caac. 21352.
  • Abbasi NR, Shaw HM, Rigel DS, et al. Early diagnosis of cutaneous melanoma: revisiting the ABCD criteria. JAMA 2004;292(22):2771–6.
  • Glazer AM, Winkelmann RR, Farberg AS, et al. Quantitative ABCD parameters measured by a multispectral digital skin lesion analysis device for evaluation of suspicious pigmented lesions strongly correlate with clinical ABCD observations. J Am Acad Dermatol 2017;76(6):AB212(Suppl 1).