
Nonmelanoma Skin Cancers You Need to Know
Nonmelanoma skin cancer (NMSC)—primarily basal cell carcinoma (BCC) and squamous cell carcinoma (SCC)—is the most common form of human neoplasia. NMSC is primarily caused by exposure to the ultraviolet (UV) A and B rays of the sun.[1] The image above shows superficial BCC on the trunk.
An estimated 5.4 million cases of NMSC (80% BCC, 20% SCC) are diagnosed annually in approximately 3.3 million Americans (with some individuals having more than one lesion), with an estimated 2000 deaths each year[1]; therefore, early identification of these lesions is critically important. However, NMSC can be difficult to diagnose because its appearance varies so widely in color, morphology, and texture. Can you correctly diagnose the lesions in our slideshow?
Nonmelanoma Skin Cancers You Need to Know
What is the likely diagnosis for the patient shown here?
Nonmelanoma Skin Cancers You Need to Know
Answer: Actinic keratosis
Actinic keratosis (AK or solar keratosis), a precursor to SCC, is the most common lesion with malignant potential.[2] AK occurs on skin that has been chronically exposed to the sun, such as on the face, ears, scalp, back, forearms, backs of the hands, or legs.[4] The bald area of the scalp or forehead is a common location for AK.[2,3] AK can regress, persist unchanged, or progress to invasive SCC.[2] Another form of AK, actinic cheilitis, develops almost exclusively on the lower lip and may evolve into SCC.[2,3]
Nonmelanoma Skin Cancers You Need to Know
In this patient, multiple AKs have developed on the forearm, a common location for these lesions. AKs present as red, pink, or brown scaly patches.[2-4] Early AKs can be rough and feel like sandpaper; some are easier to feel than to see. The lesions range in size from 2-10 mm.
Nonmelanoma Skin Cancers You Need to Know
What is the diagnosis for the patient shown here?
Nonmelanoma Skin Cancers You Need to Know
Answer: Cutaneous horn
An exaggerated hyperkeratosis has developed into a cutaneous horn, a conical projection above the surface of the skin that resembles a miniature horn.[5] The horn is composed of compacted keratin.[5,6] The cutaneous horn is most commonly found on the dorsum of the hands, but it can also develop on the scalp or other locations, such as the face or the ear.[5] These lesions develop most often in elderly people in their 60s and 70s. The base of the lesion can be a malignancy, usually SCC, a precancerous lesion as an AK, or a benign growth such as a seborrheic keratosis.[5,6] Lesions that are tender at the base and those of larger size are more likely to be malignant.[5]
Nonmelanoma Skin Cancers You Need to Know
What is the likely diagnosis for the patient shown here?
Nonmelanoma Skin Cancers You Need to Know
Answer: Basal cell carcinoma
The hallmark of BCC, the most common form of cancer in the United States, is its waxy, translucent, or pearly appearance.[7,8] There is often a raised, pale, sometimes indistinct border and a central ulceration. A closer look often reveals telangiectasias (tiny, superficial, tortuous blood vessels), a feature that contributes to easy bleeding if the lesion is traumatized. Skin atrophy may be present.[7,8] A slow-growing and generally painless lesion, BCC may take months to reach a size sufficient for a patient to recognize.[8] BCC is friable and prone to ulceration, manifesting as chronic, “non-healing” sores that eventually cause patients to seek medical attention. BCC can be locally invasive and destructive. Although BCCs rarely metastasize, cosmetic disfigurement is not uncommon, because they usually occur on the head and neck.
Nonmelanoma Skin Cancers You Need to Know
The clinical presentation of BCC varies by subtype (eg, nodular, infiltrative, micronodular, morpheaform, superficial).[8] The image shows a superficial BCC on a patient's heavily sun-damaged upper back. Superficial BCC starts out as a scaly patch or papule that varies in color (flesh, pink, red, or brown).[8] Occasionally, minute eschars may appear within the patch. Superficial BCCs usually form on the trunk or shoulders. Erosion of these lesions is uncommon, but they are friable and can bleed easily.
Nonmelanoma Skin Cancers You Need to Know
This image shows another example of a superficial BCC on a sun-exposed area from the same patient as in the previous slide. The lesion is a shiny pink and erythematous, fairly well-circumscribed thin plaque. Sometimes these lesions are scaly, and they can be mistaken for eczema or psoriasis if the patient complains of itching.[8] Superficial BCCs, which progress very slowly,[8] can also appear multicentric, with areas of clinically normal skin interspersed with clinically involved areas.
Nonmelanoma Skin Cancers You Need to Know
This patient has a nodular BCC, just barely visible as an almost translucent nodule on his chin (arrow). On closer examination, telangiectasia is visible on the nodule's surface. As the nodule grows, it can ulcerate and give the appearance of having rolled edges. Nodular BCCs are the most common subtype of BCC[8]; they occur most often on the head (especially paranasal and periauricular areas), neck, and upper back. The lesions usually develop as round nodules that are waxy, pearly, or flesh-colored, with well-demarcated borders.[8] Minor trauma can cause bleeding and crusting.
Nonmelanoma Skin Cancers You Need to Know
This lesion is known as a rodent ulcer,[7,9] named for its resemblance to a rat bite. The rodent ulcer is a nodular BCC.[9] The rat bite morphology is a consequence of central ulceration of nodular BCCs.
Nonmelanoma Skin Cancers You Need to Know
This patient has a morpheaform BCC, an uncommon sclerosing variant of BCC in which tumor cells induce a proliferation of fibroblasts within the dermis, as well as increased collagen deposition (sclerosis).[8] The lesions usually occur on the face. They may clinically resemble thickened pink or flesh-colored scars, or they may appear as white or yellow, waxy, sclerotic (scarlike) plaques. Morpheaform BCCs slowly expand and can grow quite large before they develop nodules and are recognized as BCCs; this slow, difficult-to-visualize course increases the morbidity of the cancer.[9] The margins are also hard to distinguish.[10]
Nonmelanoma Skin Cancers You Need to Know
This morpheaform BCC is a sclerotic plaque with an ill-defined and raised border. Sometimes these lesions are mistaken for scar tissue. The bleeding, ulceration, and crusting that are common with most BCCs are often absent in morpheaform BCCs.[8]
Nonmelanoma Skin Cancers You Need to Know
This lesion has a small, black area, but it also has a pearly appearance, a central ulceration, and telangiectasia—all of which suggest a pigmented BCC, an uncommon variant of nodular BCC,[8] rather than melanoma. However, it is important to assume that these are melanomas until proven otherwise by biopsy.[8-10] Pigmented BCCs can have areas of color varying from shades of brown to black, in all or part of the nodule, making these lesions appear at first glance to be possible melanomas. In some pigmented BCCs, areas of the tumor do not retain pigment.
Nonmelanoma Skin Cancers You Need to Know
This patient's facial lesion has a pearly appearance, raised borders, and a central depression—all features consistent with BCC. However, with its mixture of colors, including brown and black, this growth also has features in common with melanoma.[8-10] Therefore, it is essential to perform a biopsy, as though the neoplasm were melanoma, to clearly establish the histology of this lesion. Above all, a diagnosis should not be made clinically nor should treatment for a pigmented BCC proceed until a biopsy confirms the diagnosis.[8-10]
Nonmelanoma Skin Cancers You Need to Know
What is the likely diagnosis for the lesion shown here?
Nonmelanoma Skin Cancers You Need to Know
Answer: Basosquamous carcinoma
Basosquamous carcinoma, as the name suggests, has features of both BCC and SCC.[9,11,12] This relatively uncommon lesion is sometimes considered a more aggressive variant of BCC,[9] but it has a higher rate of local recurrence and metastasis than BCC because of its infiltrative growth and stromal reaction patterns.[11,12] Because basosquamous carcinoma has no distinctive clinical features, the diagnosis must be made by biopsy.[11] Basosquamous carcinomas occur primarily (80%) on the head and neck, often in the paranasal area. Although most occur on sun-exposed skin, some develop on sun-protected skin.[11] Lesions that develop on sun-exposed skin are usually more aggressive.
Nonmelanoma Skin Cancers You Need to Know
What is the likely diagnosis for the lesion shown here?
Nonmelanoma Skin Cancers You Need to Know
Answer: Bowen disease
Bowen disease is a superficial type of SCC (SCC in situ).[13] The lesion begins as an asymptomatic, slowly enlarging, erythematous, slightly elevated scaly patch or plaque, with irregular and sharply demarcated borders.[13,14] Bowen disease can occur on any mucocutaneous surface, but it is most commonly found on the head, neck, and arms. Occasionally, the lesions are pigmented, especially those in the genital region or under the nails. Lesions in these locations can simulate melanoma. The early features of Bowen disease can be subtle and may be limited to dry surface scaling, resulting in a delay in diagnosis. The scaly, reddened patch can become hyperkeratotic, crusted, fissured, or ulcerated.[13,14] In most cases, Bowen disease presents as a single lesion. Lesions vary in size from a few millimeters to several centimeters in diameter.[14]
Nonmelanoma Skin Cancers You Need to Know
What is the likely diagnosis for the lesion shown here?
Nonmelanoma Skin Cancers You Need to Know
Answer: Keratoacanthoma
Keratoacanthoma is a relatively common skin cancer that originates in the pilosebaceous glands (hair follicle/sebaceous gland)[15] and closely resembles an SCC.[15-17] Some studies support classifying keratoacanthoma as a variant of invasive SCC.[18,19] In most pathology/biopsy reports, dermatopathologists refer to the lesion as "squamous cell carcinoma, keratoacanthoma-type." However, some studies have argued for a distinction between keratoacanthoma and SCC based on gene expression[20] or cutaneous markers.[21]
The keratoacanthoma in this image is located on the patient's helical rim and displays the characteristic features of a round nodule with a central, craterlike depression filled with keratin. The lesions are usually solitary, beginning as firm, round, skin-colored or reddish papules that rapidly progress to dome-shaped nodules with a smooth, shiny surface and a central ulceration or keratin plug that may project like a horn.[15-17] At the base of the tumor, islands and strands of atypical cells may invade the dermis. These lesions are usually located on sun-exposed skin, especially the face, ears, neck, and dorsal surfaces of the hands and forearms. Truncal lesions are less common.
Nonmelanoma Skin Cancers You Need to Know
This image shows a typical keratoacanthoma located on the neck. Keratoacanthomas appear only on hair-bearing surfaces of the skin, which suggests that they might arise from a single hair follicle at a sun-exposed area of injured skin.[22,23]
Nonmelanoma Skin Cancers You Need to Know
What is the likely diagnosis for the patient shown here?
Nonmelanoma Skin Cancers You Need to Know
Answer: Cutaneous squamous cell carcinoma
Cutaneous SCC is the second most common type of skin cancer in light-complexioned individuals,[1,24,25] with an annual estimate of more than 1 million cases diagnosed in the United States.[26] The SCC shown is a round, erythematous plaque that appears inflamed and scaly, with raised edges and a shallow central ulcer. SCC is a malignant disease of epidermal keratinocytes.[24,25] About 50% of SCC cases (range, 40-60%) develop from untreated AKs.[26] SCC is a slow-growing cancer that occurs most often in people with long-term UV exposure, including from the use of tanning beds.[1,25,26] SCC typically develops in areas of preexisting solar skin damage, chronic inflammation, or scars (such as burns). Unlike almost all BCCs, which rarely metastasize, cutaneous SCC is associated with a risk for metastasis.
Nonmelanoma Skin Cancers You Need to Know
About 70% of SCC occurs on the head and neck.[24,25] Clinically, SCC presents as a thickened, enlarging papule, nodule or plaque of skin with a rough, irregular surface that bleeds or crusts easily if traumatized. The lesion often has well-defined, raised borders and a shallow ulcer in the center. When a large SCC is found on the face, cranial nerve function, particularly in the facial trigeminal distribution, should be assessed (numbness, pain, tingling, weakness, and asymmetry).[24,25] Clinical evidence of cranial nerve dysfunction suggests an aggressive tumor that has invaded the perineural area.
Nonmelanoma Skin Cancers You Need to Know
The lesion on this man's ear has all of the typical SCC features: a round, sharply defined, scaly plaque with raised borders, a central ulceration, and an inflamed appearance. SCC is 2-3 times more common in men than in women, and because the risk for SCC is proportional to the extent of cumulative, long-term sun exposure, the risk also increases with age.[24-26] Other risk factors for SCC include ionizing radiation exposure, human papillomavirus infection, thermal injury, immunosuppression, exposure to chemical carcinogens, and diseases such as xeroderma pigmentosum, oculocutaneous albinism, and junctional epidermolysis bullosa. Organ transplantation is another significant risk factor[1,24-26]; for instance, SCC is the most common malignancy in renal transplant recipients.[24,27,28]
Nonmelanoma Skin Cancers You Need to Know
SCC can manifest as a cutaneous horn (shown). A well-defined, cone-shaped hyperkeratotic growth has arisen from the lesion’s base; the growth is a cutaneous SCC, but various other types of lesions can also be found at the base of a cutaneous horn. The keratotic component of these lesions can range in color from yellow to brown to gray; on palpation, they have a hard consistency.[26,29] Following treatment, the rates of local recurrence of cutaneous SCCs range from less than 1% to 23%, depending on the location, size, and type of therapy.
If left untreated, SCC can invade the skin and become disfiguring or even metastasize to the lymphatic system and then to distant tissues and organs (usually the lungs), potentially leading to death. A cutaneous SCC arising from a chronic scar is more likely to metastasize than one originating from an AK.
Nonmelanoma Skin Cancers You Need to Know
About 90% of lip tumors are SCC, with the lower lip usually affected.[30] Lip SCC occurs more often in men than in women, likely because many women use lipstick or lip salve. In addition to sun exposure, smoking is a risk factor for SCC of the lip.[30] The lips are more susceptible to damaging effects of the environment because of a thinner epithelium, lack of keratotic covering, and smaller amounts of melanin.
Nonmelanoma Skin Cancers You Need to Know
SCCs of the lip have a variable presentation. They usually begin as localized and superficial lesions that grow slowly. SCCs of the lip have higher metastatic potential than other cutaneous SCCs.[31] Smaller lesions (<2 cm in diameter) without lymph node involvement have a better prognosis.[24] The patient should be examined for submental and submaxillary lymphadenopathy. SCC of the lower lip may be a consequence of previous solar damage to the lip (actinic cheilitis/solar cheilosis).[24]
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