Author: Anushka Pradhan
Editor: Nicholas Jo
Overview
Nonmelanoma skin cancer (NMSC) can be divided into two forms of carcinoma: (1) a basal carcinoma (BCC), which accounts for 75% of cases, and is a slow-growing, locally invasive tumour or (2) a cutaneous squamous cell carcinoma (SCC), which accounts for the remainder of cases of NMSC (Samarasinghe, 2012). Compared to BCC, SCC has a significant rate of metastasis (Samarasinghe, 2012).
Keywords
Nonmelanoma Skin Cancer, Skin Cancer Biopsy
Epidemiology
NMSC is the most common type of cancer in Caucasians. The incidence of NMSC has increased up to 10% annually, with 2–3 million new cases of NMSC diagnosed worldwide every year (Samarasinghe, 2012).
Etiology
A combination of environmental, genetic and phenotypic factors may be responsible for the development of NMSC (Samarasinghe, 2012). Approximately 90% of NMSCs occur as a result of exposure to ultraviolet (UV) light (Griffin, 2016). BCC and SCC both occur due to malignant transformation of keratinocytes and suppression of the cutaneous inflammatory response (Griffin, 2016).
Symptoms
Common symptoms of Nonmelanoma skin cancer include the following:
- Classical nodular subtype presents as a pink, pearly papule with a rolled edge and central ulceration,
- SCC present as ulcers or indurated keratinizing lesions on sun-exposed sites,
- Superficial BCCs present as slowly enlarging erythematous plaques, frequently found on the trunk (Griffin, 2016).
Risk Factors
Exposure to UV light is the leading risk factor for this disease (Griffin, 2016). HIV infection may also confer a significant risk (Griffin, 2016). Phenotypic features most associated with an increased risk include fair or red hair, blue eyes, an increasing number of melanocytic naevi and Fitzpatrick skin type I (Samarasinghe, 2012).
Diagnosis
Clinical Features
Clinical presentation of this condition is heterogeneous concerning lesion location, size, thickness and pigmentation (Samarasinghe, 2012). The diagnosis of NMSC in classical cases can be made clinically, and most features depend upon the subtype (Samarasinghe, 2012). Nodular BCC is the most common subtype, presenting as pink nodules, with rolled edges, surface telangiectasia, ulceration, or crusting (Samarasinghe, 2012).
Pathological Features
Dermoscopy can be used to diagnose BCC, with leaf-like areas, blue-grey blotches, wheel-spoke like areas, and arborizing blood vessels indicating disease (Samarasinghe, 2012). Additionally, a skin biopsy allows the stratification of tumours into high- and low-risk malignancies (Samarasinghe, 2012). Other non-invasive diagnostic techniques include in vivo reflectance confocal microscopy or optical coherence tomography (Cives, 2020).
Treatment Protocol
Pharmacological Treatment
Topical treatment is generally reserved for the management of patients with low-risk BCC (Cives, 2020). Photodynamic therapy uses a photosensitizing agent to produce photo-active porphyrins in malignant keratinocytes, which results in the release of reactive oxygen species and free radical formation (Cives, 2020).
Non-Pharmacological Treatment
Mohs micrographic surgery (MMS) is the gold standard treatment for high-risk BCC and SCC (Cives, 2020). If the patient is unable to undergo this surgery, excision with wide margins or radiotherapy may be considered (Cives, 2020). Upon complete clearance, the wound is repaired by direct closure, local skin flap or skin graft (Cives, 2020).
Articles on Misdiagnosis
Gao, Y., Yuan, J., Arron, S., & A. Raymond. (2017). Exposed hardware: two cases in patients with invasive non melanoma skin cancer. Journal of the American Academy of Dermatology, 76(6), AB135-AB135. DOI: 10.1016/j.jaad.2017.04.528.
Rees, J.R., Zens, M.S., Gui, J., Celaya, M.O., Riddle, B.L., & M.R. Karagas. (2014). Non Melanoma skin cancer and subsequent cancer risk. Plos One, 9(6), e99674. DOI: 10.1371/journal.pone.0099674.
References
Cives, M., Mannavola, F., Lospalluti, L., Sergi, M. C., Cazzato, G., Filoni, E., Cavallo, F., Giudice, G., Stucci, L. S., Porta, C., & Tucci, M. (2020). Non-Melanoma Skin Cancers: Biological and Clinical Features. International journal of molecular sciences, 21(15), 5394. DOI: 10.3390/ijms21155394.
Griffin, L. L., Ali, F. R., & Lear, J. T. (2016). Non-melanoma skin cancer. Clinical medicine (London, England), 16(1), 62–65. DOI: 10.7861/clinmedicine.16-1-62.
Samarasinghe, V., & Madan, V. (2012). Nonmelanoma skin cancer. Journal of cutaneous and aesthetic surgery, 5(1), 3–10. DOI: 10.4103/0974-2077.94323.
