Overview of skin cancer

Related Diseases & Conditions

• Merkel cell carcinoma

  Summary

  Merkel cell carcinoma is a rare, aggressive cutaneous neuroendocrine neoplasm that primarily affects white adults. Incidence increases with age and is highest among those >85 years of age.[5] Two distinct etiologies are recognized: exposure to UV radiation and oncogenic transformation by Merkel cell polyomavirus. Key risk factors are advancing age, immunosuppression, and light skin type. Diagnosis is confirmed with skin biopsy and histopathologic evaluation including immunohistochemistry. Occult metastasis is common, and sentinel lymph node biopsy and imaging are important tools for staging the disease.​ The tumor typically presents as an asymptomatic, rapidly growing, pink-to-violaceous or skin-colored dermal or subcutaneous nodule.[6]
• Basal cell carcinoma

  Summary

  The most prevalent malignancy of the skin in fair-skinned adults in the world.[7] [8]​ It typically presents as pearly papules and/or firm plaques; nonhealing scabs; small crusts and nonhealing wounds; plaques, nodules, and tumors with rolled borders; and/or papules with associated telangiectasias.[9] [10]Image​​ Strong risk factors include UV radiation via frequent sun exposure, x-ray exposure, arsenic exposure, xeroderma pigmentosum, nevoid basal cell carcinoma (Gorlin-Goltz syndrome), and history of transplantation. Metastases and advanced lesions are uncommon. Diagnosis is histologic.
• Squamous cell carcinoma (SCC)

  Summary

  SCC is the proliferation of atypical, transformed keratinocytes in the skin with malignant behavior. Ranges from in situ tumors (Bowen disease) to invasive tumors and metastatic disease. Second most common nonmelanoma skin cancer worldwide, secondary to basal cell carcinoma.[8]​ Patients commonly present with a new or englarging lesion that they are concerned about, which may be tender or itchy, or a nonhealing wound originally caused by some trauma. In situ tumors are typically thin, flesh-colored to erythematous, scaly or hemorrhagic plaques, while invasive SCC may present as an exophytic tumor or ulcer.Image​ Tumors may be friable and bleed easily and are located mostly on sun-exposed areas of skin, such as the head and neck (84%) and extensor upper extremities (13%).[11] Cumulative UV exposure and immunosuppression are major risk factors. Presumptive diagnosis of SCC of the skin is usually based on a thorough history and clinical findings; however, skin biopsy confirms the diagnosis.[12]
• Melanoma

  Summary

  A malignant tumor arising from pigment-producing melanocytes found in the skin, eye, and central nervous system. Several variants exist. Clinical features of lesion asymmetry, border irregularity, color variability, diameter >6 mm, and evolution over time should raise suspicion for melanoma and prompt further assessment with dermoscopy.[13]Image​​ Lesions are often on sun-exposed anatomic locations and more often in people with Fitzpatrick type I (white) skin. Lesions are more common on the trunk in men and on the legs and feet in women.[14] Early melanoma may be asymptomatic. History regarding a new or changing pigmented lesion should be obtained.
• Kaposi sarcoma

  Summary

  A low-grade lymphovascular neoplasm associated with human herpesvirus-8 (HHV-8, also known as Kaposi sarcoma-associated herpesvirus [KSHV]) infection.[15] Lesions frequently involve mucocutaneous sites, but may become more extensive to involve the lymph nodes and visceral organs. Skin lesions evolve from an early patch, to a plaque, and later to ulcerating tumor nodules.Image ​There are four main subtypes: classic (sporadic); endemic (observed in sub-Saharan Africa); HIV-associated (formerly known as epidemic or AIDS-related); iatrogenic (transplant-related).​ Diagnosis is confirmed by biopsy and histopathology.[16]
• Cutaneous T-cell lymphoma

  Summary

  Heterogeneous group of uncommon disorders characterized by clonal accumulation of T lymphocytes primarily or exclusively in the skin. The incidence of cutaneous T-cell lymphomas has been reported as <10 per 100,000 population globally.[17] While the etiology remains unclear, theories include causative genomic alterations and infectious agents.​ Mycosis fungoides and its leukemic variant, Sézary syndrome, are the most common subtypes.[18] Establishing a diagnosis is often difficult, as the disease can manifest in a number of different ways, including flat patches, raised plaques, large tumors, and/or marked erythroderma (intense and widespread reddening of the skin).Image​​​ Diagnosis is based on clinical findings, skin biopsy (specimens should be sent for histology, immunophenotyping, and molecular studies), and laboratory blood tests, and usually requires specialist expertise.[19]​[20]
• Actinic keratosis

  Summary

  Chronic keratotic lesions on adult skin that has been chronically exposed to UV rays. Lesions are skin-colored, yellowish, or erythematous, ill-defined, irregularly shaped, small, scaly macules or plaques localized in sun-exposed areas of the body (e.g., forehead, lower lip, dorsum of the hands and forearms, bald areas of the scalp, and ears).Image​ Typically, they occur in men age >40 years with light-colored skin and a history of chronic sun exposure. Actinic keratosis has the potential to progress into an invasive SCC. The risk of progression to SCC has been calculated to be between 0.025% and 16% per year.[21] [22]​ Although diagnosed clinically, a biopsy may help to rule out SCC.
• Sunburn

  Summary

  Sunburn is an acute inflammatory reaction of the skin induced by overexposure to UV radiation. Skin findings include erythema and edema, with or without vesiculation, followed by desquamation. Key risk factors include Fitzpatrick skin type I-III, photo-sensitizing drug, intentional tanning, and lack of or improper use of sunscreen. Symptoms include pain and/or pruritus. Characteristic history and physical exam findings are usually sufficient to make the diagnosis of sunburn. Primary prevention via sun avoidance, physical protection, and the appropriate use of sunscreen is key to preventing the condition, as cellular damage caused by UV radiation is irreversible and may with time increase the risk of skin cancer.