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Clinical presentation of actinic keratoses and squamous cell carcinoma
Clinical presentation of actinic keratoses and squamous cell carcinoma Ronald L. Moy, MD Los Angeles, California Background: Actinic keratosis is a skin lesion that can progress to squamous cell carcinoma but cannot always be clinically distinguished from a squamous cell carcinoma. Objective: The purpose of this article is to describe the clinical presentation of actinic keratoses and squamous cell carcinoma. Methods: The author’s clinical experience and a review of the literature were used to describe actinic keratoses and squamous cell carcinoma. Results: There is a continuum and a progression from actinic keratoses to squamous cell carcinoma so that there is no way to reliably distinguish between the two diagnoses. Conclusion: Because it can be impossible to distinguish between an actinic keratosis and squamous cell carcinoma, treatment of actinic keratoses should be aggressive to stop the progression to squamous cell carcinoma. (J Am Acad Dermatol 2000;42:S8-10.)
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ctinic keratosis is the initial lesion in a disease continuum that progresses to invasive squamous cell carcinoma. In one study, 97% of squamous cell carcinomas were associated with a From the University of California at Los Angeles and the Veterans Administration West Los Angeles Medical Center. Reprint requests: Ronald L. Moy, MD, 100 UCLA Medical Plaza, Suite 590, Los Angeles, CA 90024. 0190-9622/2000/$12.00 + 0 16/0/103343
contiguous actinic keratosis.1 Squamous cell carcinoma accounts for thousands of preventable skin cancer deaths each year. The average person with actinic keratosis is the elderly patient with fair skin and a history of excessive sun exposure. The most important causative factor is long-term sun exposure. Young adults can have actinic keratoses if they have a fair complexion and sufficient sun exposure. Actinic keratosis increases in prevalence with increasing age.2 Other risk factors
4-C Fig 1. Actinic keratosis: Red, scaling plaques on hand.
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J AM ACAD DERMATOL VOLUME 42, NUMBER 1, PART 2
4-C Fig 2. Multiple actinic keratoses of scalp (impossible to distinguish from squamous cell carcinomas).
4-C Fig 3. Cutaneous horn, variant of actinic keratosis.
for actinic keratosis include being immunosuppressed or having certain genetic diseases such as xeroderma pigmentosum. Organ transplant patients who are taking immunosuppressive drugs will be a larger group of the patients who will have actinic keratosis and squamous cell carcinoma. The most common clinical presentation of an actinic keratosis is a red, scaling papule or plaque on a sun-exposed area (Fig 1). It is usually 1 to 3 mm in diameter but can be several centimeters in size and numerous or confluent in sun-exposed areas. The surrounding areas may show evidence of sun damage with broken blood vessels, yellowish discoloration, and blotchy pigmentation. The scaliness can often be felt before it can be seen. The rough, elevated bumps
can be red or skin colored. Actinic keratoses often occur as multiple lesions on a bald scalp, the back of the hand, or the face. Actinic keratoses can progress into thickened or hypertrophic lesions4 (Fig 2). The thickened lesions can progress to squamous cell carcinoma and be clinically indistinguishable from squamous cell carcinoma. The symptoms that a patient may report include tenderness, itchiness, and burning. These symptoms can be the same in either actinic keratosis or squamous cell carcinoma.3 The clinical variants of actinic keratosis include the cutaneous horn, lichen planus–like keratosis, the pigmented actinic keratosis, and actinic cheilitis. The cutaneous horn is a hypertrophic type of actinic keratosis with a hyperkeratotic protuberance that occurs
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4-C
4-C Fig 5. Actinic cheilitis on the lips.
Fig 4. Pigmented actinic keratosis on the cheek.
in a conical shape above the skin surface (Fig 3). A percentage of these cutaneous horns (15.7%) are actually squamous cell carcinoma.5 There is no way to discriminate between a cutaneous horn that is a type of actinic keratosis and a squamous cell carcinoma without performing a biopsy. The pigmented actinic keratosis can resemble a scaling lentigo (Fig 4) that histologically has features of actinic keratosis. Actinic keratosis may also develop on the conjunctiva, called pinguecula or pterygium. Actinic cheilitis is really actinic keratosis occurring on the lower lips (Fig 5). The lips are rough, scaly, and red; they may also exhibit fissuring, scaliness, and ulcerations. Focal hyperkeratosis and leukoplakia may be seen. The patient may complain of a constant dry lip. These are the same findings that can be seen in squamous cell carcinoma of the lip. Squamous cell carcinomas of the lip are particularly worrisome because they have approximately an 11% metastatic rate, which is higher than other cutaneous squamous cell carcinomas.6 There is no definite way to distinguish between an actinic keratosis and a squamous cell carcinoma without performing a biopsy. An increase in thickness, redness, pain, ulceration, and size may suggest a progression to squamous cell carcinoma, but these
are not absolute criteria. Histologically and clinically, there is a continuum and a progression between these two diagnoses that makes reliable distinction between the diseases almost impossible; one evolves into the other without any clear features distinguishing the two. Thus it is impossible to predict the point at which an individual actinic keratosis will evolve into an invasive squamous cell carcinoma. Because it can be impossible to distinguish between actinic keratosis and some squamous cell carcinomas, treatment can be difficult. Many lesions thought to be actinic keratoses are actually squamous cell carcinomas but are treated as actinic keratoses. This forces the clinician to perform biopsies on lesions thought to be actinic keratosis that are not responding to treatment. The fact that many lesions being treated as actinic keratosis could really be early squamous cell carcinomas suggests that treatment should be aggressive and that patients should be monitored closely so that the eventual progression from actinic keratosis to squamous cell carcinoma may be stopped. REFERENCES 1. Hurwitz RM, Monger LE.Solar keratosis: an evolving squamous cell carcinoma: Benign or malignant? Dermatol Surg 1995;21:183-6. 2. Green A, Beardmore G, Hart V, et al. Skin cancer in a Queensland population. J Am Acad Dermatol 1988;19:1045-52. 3. Schwartz RA. The actinic keratosis. Dermatol Surg 1997;23: 1009-19. 4. Billano RA, Little WP. Hypertrophic actinic keratosis. J Am Acad Dermatol 1982;7:484-9. 5. Yu RCH, Pryce DW, MacFarlane AQ, Stewart TW. A histopathological study of 643 cutaneous horns. Br J Dermatol 1991;24:449-52. 6. Picascia DD, Robinson JK. Actinic cheilitis: a review of the etiology, differential diagnosis, and treatment. J Am Acad Dermatol 1987;17:255-64.
A
ctinic keratosis is the initial lesion in a disease continuum that progresses to invasive squamous cell carcinoma. In one study, 97% of squamous cell carcinomas were associated with a From the University of California at Los Angeles and the Veterans Administration West Los Angeles Medical Center. Reprint requests: Ronald L. Moy, MD, 100 UCLA Medical Plaza, Suite 590, Los Angeles, CA 90024. 0190-9622/2000/$12.00 + 0 16/0/103343
contiguous actinic keratosis.1 Squamous cell carcinoma accounts for thousands of preventable skin cancer deaths each year. The average person with actinic keratosis is the elderly patient with fair skin and a history of excessive sun exposure. The most important causative factor is long-term sun exposure. Young adults can have actinic keratoses if they have a fair complexion and sufficient sun exposure. Actinic keratosis increases in prevalence with increasing age.2 Other risk factors
4-C Fig 1. Actinic keratosis: Red, scaling plaques on hand.
S8
Moy S9
J AM ACAD DERMATOL VOLUME 42, NUMBER 1, PART 2
4-C Fig 2. Multiple actinic keratoses of scalp (impossible to distinguish from squamous cell carcinomas).
4-C Fig 3. Cutaneous horn, variant of actinic keratosis.
for actinic keratosis include being immunosuppressed or having certain genetic diseases such as xeroderma pigmentosum. Organ transplant patients who are taking immunosuppressive drugs will be a larger group of the patients who will have actinic keratosis and squamous cell carcinoma. The most common clinical presentation of an actinic keratosis is a red, scaling papule or plaque on a sun-exposed area (Fig 1). It is usually 1 to 3 mm in diameter but can be several centimeters in size and numerous or confluent in sun-exposed areas. The surrounding areas may show evidence of sun damage with broken blood vessels, yellowish discoloration, and blotchy pigmentation. The scaliness can often be felt before it can be seen. The rough, elevated bumps
can be red or skin colored. Actinic keratoses often occur as multiple lesions on a bald scalp, the back of the hand, or the face. Actinic keratoses can progress into thickened or hypertrophic lesions4 (Fig 2). The thickened lesions can progress to squamous cell carcinoma and be clinically indistinguishable from squamous cell carcinoma. The symptoms that a patient may report include tenderness, itchiness, and burning. These symptoms can be the same in either actinic keratosis or squamous cell carcinoma.3 The clinical variants of actinic keratosis include the cutaneous horn, lichen planus–like keratosis, the pigmented actinic keratosis, and actinic cheilitis. The cutaneous horn is a hypertrophic type of actinic keratosis with a hyperkeratotic protuberance that occurs
S10 Moy
J AM ACAD DERMATOL JANUARY 2000
4-C
4-C Fig 5. Actinic cheilitis on the lips.
Fig 4. Pigmented actinic keratosis on the cheek.
in a conical shape above the skin surface (Fig 3). A percentage of these cutaneous horns (15.7%) are actually squamous cell carcinoma.5 There is no way to discriminate between a cutaneous horn that is a type of actinic keratosis and a squamous cell carcinoma without performing a biopsy. The pigmented actinic keratosis can resemble a scaling lentigo (Fig 4) that histologically has features of actinic keratosis. Actinic keratosis may also develop on the conjunctiva, called pinguecula or pterygium. Actinic cheilitis is really actinic keratosis occurring on the lower lips (Fig 5). The lips are rough, scaly, and red; they may also exhibit fissuring, scaliness, and ulcerations. Focal hyperkeratosis and leukoplakia may be seen. The patient may complain of a constant dry lip. These are the same findings that can be seen in squamous cell carcinoma of the lip. Squamous cell carcinomas of the lip are particularly worrisome because they have approximately an 11% metastatic rate, which is higher than other cutaneous squamous cell carcinomas.6 There is no definite way to distinguish between an actinic keratosis and a squamous cell carcinoma without performing a biopsy. An increase in thickness, redness, pain, ulceration, and size may suggest a progression to squamous cell carcinoma, but these
are not absolute criteria. Histologically and clinically, there is a continuum and a progression between these two diagnoses that makes reliable distinction between the diseases almost impossible; one evolves into the other without any clear features distinguishing the two. Thus it is impossible to predict the point at which an individual actinic keratosis will evolve into an invasive squamous cell carcinoma. Because it can be impossible to distinguish between actinic keratosis and some squamous cell carcinomas, treatment can be difficult. Many lesions thought to be actinic keratoses are actually squamous cell carcinomas but are treated as actinic keratoses. This forces the clinician to perform biopsies on lesions thought to be actinic keratosis that are not responding to treatment. The fact that many lesions being treated as actinic keratosis could really be early squamous cell carcinomas suggests that treatment should be aggressive and that patients should be monitored closely so that the eventual progression from actinic keratosis to squamous cell carcinoma may be stopped. REFERENCES 1. Hurwitz RM, Monger LE.Solar keratosis: an evolving squamous cell carcinoma: Benign or malignant? Dermatol Surg 1995;21:183-6. 2. Green A, Beardmore G, Hart V, et al. Skin cancer in a Queensland population. J Am Acad Dermatol 1988;19:1045-52. 3. Schwartz RA. The actinic keratosis. Dermatol Surg 1997;23: 1009-19. 4. Billano RA, Little WP. Hypertrophic actinic keratosis. J Am Acad Dermatol 1982;7:484-9. 5. Yu RCH, Pryce DW, MacFarlane AQ, Stewart TW. A histopathological study of 643 cutaneous horns. Br J Dermatol 1991;24:449-52. 6. Picascia DD, Robinson JK. Actinic cheilitis: a review of the etiology, differential diagnosis, and treatment. J Am Acad Dermatol 1987;17:255-64.