Solar lentigines / seborrheic keratoses / lichen planus-like keratosis
|Description||In this chapter we cover the dermoscopyDermoscopy is a non invasive diagnostic method. criteriaThis glossary term has not yet been described. of solar lentiginesThis glossary term has not yet been described., seborrheic keratosesThis glossary term has not yet been described. and lichen planus like keratoses (LKPL)|
|Author(s)||Ralph P. Braun · Stephanie Nouveau · Harold Rabinovitz · Maggie Oliviero|
|Owner||Ralph Braun → send e-mail|
|Status update||May 28, 2017|
|Status by||Ralph P. Braun|
| Subchapter(s): |
Lichen planus-like keratosis
- 1 Solar lentigo
- 2 Seborrheic keratoses
- 3 Lichen Planus-like Keratosis
Solar lentiginesThis glossary term has not yet been described. are sharply circumscribed, uniformly pigmented macules that are located predominantly on the sun-exposed areas of the skinThis glossary term has not yet been described., such as the dorsum of the hands, the shoulders, and the scalp. Lentigines are a result of hyperplasia of keratinocytes and melanocytes, with increased accumulation of melanin in the keratinocytes. They are induced by ultraviolet light exposure. Unlike freckles, solar lentigines persist indefinitely. Nearly 90% of Caucasians over the ageprocess of becoming older of 60 years have these lesions. Due to the increased prevalence of lentigines in the elderly, these lesions are sometimes referred to as “lentigo senilis”. However, younger individuals who tend to burn after ultraviolet exposure can also develop lentigines after acute or prolonged ultraviolet light exposure. Clinically, solar lentigines may be oval, round, or irregular in shape and can vary from a few millimeters to a few centimeters in diameter. Most lesions have a uniform light brown colorColor (American English) or colour (Commonwealth English) is the characteristic of human visual perception described through color categories, with names such as red, yellow, purple, or blue.; however, there are instances when they vary from dark brown to black. One variant of solar lentigoThis glossary term has not yet been described., “ink-spot” lentigo, has a jet-black color. Actinic purpura or other signs of solar damage can frequently be found in the skin surrounding solar lentigines. Solar lentigines are benignThis glossary term has not yet been described. lesions that can evolve to a pigmented seborrheic keratosisThis glossary term has not yet been described.. Histologically, it is characterized by club-shaped rete ridges with small nub-like extensions. In addition, there is an increased number of melanocytes and increased pigmentation in the basal keratinocytes. Although most solar lentigines are easily recognized on clinical examination, some lesions pose diagnostic challenges because their clinical appearance resembles that of melanomaThis glossary term has not yet been described.. DermoscopyDermoscopy is a non invasive diagnostic method. can be helpful in correctly differentiating a solar lentigo from melanoma. The key dermoscopic features of solar lentigines are as follows:
The presence of a sharply demarcated and irregularly curved border is characteristic of solar lentigines. Often, portions of the border are scalloped, giving a motheaten appearance
Homogenous light brown pigmentation
Many lesions have no structures or networks, only containing light brown and structureless areas; the term “jelly sign” had been proposed to describe the pigment quality of these lesions. The pigment appears as if jelly had been smeared on the skin surface.
Pigment networkGrid-like pattern consisting of interconnecting pigmented lines surrounding hypopigmented holes.
There may be an area of faint, reticulation. This correlates with the presence of melanocytes and melanin-filled keratinocytes in the rete ridges.
They are areas consisting of fi ne parallel running lines of light brown to dark brown colors. They resemble the dermatoglyphics of a human fingerprint.
Lentigines located on the scalp and faceThis glossary term has not yet been described. share features of pigmented melanocyticThis glossary term has not yet been described. lesions in this special location revealing a pseudonetworkA structureless pigment area interrupted by non-pigmented adnexal openings pattern. This is created when a diffusely pigmented area is interrupted by nonpigmented adnexal openings
In a solar lentigo the pigment around hair follicles is distributed in a symmetric fashion creating small brown circles. The pigment is usually light brown in color and similar to the color of the rest of the lesion. While the pigment is usually distributed symmetrically around the follicle, some follicles may appear asymmetrically pigmentedThis glossary term has not yet been described.. These asymmetrically pigmented follicles appear as brown crescent shaped structures. However, these asymmetric follicles will also have a brown color like the rest of the lesion. If the color of the pigment around the follicle, whether symmetric or asymmetric, is of a grayish hue or differs from the rest of the lesion then melanoma needs to enter the differential diagnosisThis glossary term has not yet been described.. Ink-spot lentigines have their own distinct dermoscopic pattern.These lesions have a very prominent blackpigmented network, which has an almost three-dimensional quality under dermoscopy. The network lines can be either thin or thick in width, and the network ends abruptly at the edge of the lesion
Seborrheic keratoses are benign epithelial lesions that can appear on any part of the body except for the mucous membranes, palmsThis glossary term has not yet been described., and solesThis glossary term has not yet been described.. The lesions are quite prevalent in people older than 30 years. The etiology of seborrheic keratoses remains unclear. Ultraviolet light exposure may be responsible for the development of some seborrheic keratoses because they appear to evolve from solar lentigines; however, many develop in areas of the skin naturally protected from ultraviolet light exposure, such as the inframammary (intertriginous) areas. Clinically, early seborrheic keratoses are light- to dark brown oval macules with sharply demarcated borders (solar lentigo). As the lesionsprogress, they transform into plaques with a waxy or stuck-on appearance. The surfaces of these lesions have a warty and keratotic appearance. Often, the lesions have follicular plugs scattered over their surfaces. The size of the lesions varies from a few millimeters to a few centimeters. Histologically, there are several distinct forms of seborrheic keratoses. In general, the lesions are characterized by papillomatous epidermal hyperplasia of uniform and monotonous keratinocytes and the presence of pseudocysts. The diagnosis of most seborrheic keratoses is straightforward. However, some seborrheic keratoses, especially the deeply pigmented variant, can simulate malignantThis glossary term has not yet been described. melanomas. Thin, early lesions have moth-eaten borders and fingerprint-like structures as described above for solar lentigines. Thicker pigmented seborrheic keratoses have the typical dermoscopy features as follows:
They are white-to-yellow, round structures that appear very bright when contrasted with their dark brown or black surroundings. The presence of multiple milia-like cystsThis glossary term has not yet been described. in pigmented seborrheic keratoses conjures up an image of “stars in the sky.” Milia-like cysts can also be seen in nonpigmented seborrheic keratosis. Milia-like cysts can also be seen in other lesions such as basal cell carcinomais the most common skin cancer, and one of the most common cancers in the United States. While BCC has a very low metastatic risk, this tumor can cause significant disfigurement by invading surrounding tissues and in melanocytic lesions including congenital neviThis glossary term has not yet been described. and melanoma. However, if the lesion is non-melanocytic and is not a basal cell carcinoma then the presence of milia-like cyst is diagnostic of seborrheic keratoses specially if more then three are seen. It is interesting to note that the quality of milia-like cysts appear somewhat different in seborrheic keratosis and melanocytic lesions. In melanoma and congenital nevi the cysts appear “starry”, which is defined as small, bright and sharp. In seborrheic keratosis they appear “cloudy”, defi ned as larger and hazier in appearance. Histologically, the cysts correspond to intraepidermal, keratin-filled cysts. It is important to be aware that milia-like cysts are more conspicuous with non-polarized dermoscopy and are often diffi cult to visualize with polarized dermoscopy.
They are round to ovoid craters that have black or brown comedo like plugs. Histologically, they correlate with keratin-fi lled invaginations of the skin surface
Fissures (sulci) are comedo-like openings[[Comedo like openings]], which are not round but rather linear and appear as dark brown to black linear to curvilinear structures within the lesion. The presence of numerous fissures and ridgeslines, curved and thick to describe the structural components of the pattern SK can result in the formation of network-like structuresThis glossary term has not yet been described. or result in a cerebriform patternIs a dermoscopy pattern that resembles the aspect of a brain. Commonly seen in seborrheic keratosis.. Histologically, they represent deep invaginations of the epidermis, fi lled with keratin.
Interlacing fissures and ridges can create an appearance of network-like structures. The quality of the grid of network-like structures in a seborrheic keratosis differs from the network grid seen in melanocytic neviThis glossary term has not yet been described. by being significantly larger. However, at times the network-like structure in a seborrheic keratosis can look very similar to that of a nevusThis glossary term has not yet been described.. Examining the lesion clinically via side lighting can make the ridges more evident, thereby making it easier to differentiate networklike ridges in seborrheic keratosis from pigment network seen in melanocytic lesions.
Cerebriform patternIs a dermoscopy pattern that resembles the aspect of a brain. Commonly seen in seborrheic keratosis.:
Multiple fissures (sulci) and ridges (gyri) may produce a cerebriform pattern, where the structures resemble sulci and gyri of the brain (brain-like appearancelines, curved and thick to describe the pattern and fissures and ridges (former synonyms “gyry and sulci” and “fat fingers”) to describe the structural components of the pattern SK). These features are generally associated with an acanthotic seborrheic keratosis.
They are linear and wide dermoscopic structures corresponding to ridges. They often appear as short sausage-shaped structures. Colors of these structures vary from tan/brown, blue and can be hypopigmented. The name has been given to these structures because their shapes can resemble a straight finger (linear), bent finger (curvilinear), or finger tip (oval–circular).
Sharply demarcated borders:
As known from clinical examination, seborrheic keratosis often have sharply demarcated borders.
Some seborrheic keratoses are associated with hairpin vesselsThis glossary term has not yet been described.. These hairpin vessels can appear as perfect “U”-shaped vessels of as “U”-shaped vessels that are twisted upon themselves. Typical hairpin blood vessels have a whitish halo around the blood vessel corresponding to the surrounding keratin. It is important to note that some melanomas can have hairpin vessels, but these vessels generally do not have the surrounding white halo but, rather have a pink halo. Similar hairpin vessels on a pin. background can be seen in irritated seborrheic keratosis.deviceThis glossary term has not yet been described.. The test is performed as follows: once the contact plate of the dermoscope is fi rmly pressed down (pressure in vertical direction) against the lesion, it is then moved slightly back and forth in the horizontal plane (parallel to the skin surface). Seborrheic keratosisThis glossary term has not yet been described. will appear to stick to the glass plate and move en bloc with the movement of the dermoscopic face plate. In other words, they will slide back and forth. In contrast, nevi will not move en bloc but, rather roll back and forth. In other words, intradermal nevi will wobble. Knowledge of the above-described dermoscopic features and patterns seen in seborrheic keratosis will often prove valuable in differentiating seborrheic keratoses from other lesions, including melanoma. However, irritated or traumatized seborrheic keratoses can mimic melanoma or squamous cell carcinomaThis glossary term has not yet been described.. In these cases the history of trauma or the presence of typical criteria for seborrheic keratoses in another part of the lesion might be comforting. However, it is important to remember that skin cancer can develop within a seborrheic keratosis, and thus a biopsy is justified for atypical appearing seborrheic keratosis.
Lichen Planus-like Keratosis
Lichen planusThis glossary term has not yet been described.-like keratosis (LPLK) is a relatively common skin lesion found on actinically damaged skin. Clinically, LPLK usually occurs as a solitary lesion with sharply demarcated borders. It may be macular or slightly raised, and has brown, tan-brown, violaceous, or red-brown color. There is also a pink variant of LPLK that resembles a basal cell carcinoma. Clinical diagnosis of LPLK lesions is often difficultThis glossary term has not yet been described. since they can mimic cutaneous malignancies. Histologically, LPLK shares some of the features seen in lichen planusThis glossary term has not yet been described.. Although the etiology of LPLK remains unknown, it is believed to be mediated by an immunologic or inflammatory response to a pre-existing Figure 5c.15 Seborrheic keratosis with many hairpin blood vessels and a few lesion, such as a seborrheic keratosis, solar lentigo, or actinic keratosisActinic keratosis (also called solar keratosis and senile keratosis; abbreviated as AK) is a pre-cancerous patch of thick, scaly, or crusty skin. These growths are more common in fair-skinned people and those who are frequently in the sun. They usually form when skin gets damaged by ultraviolet (UV) radiation from the sun or indoor tanning beds. AKs are considered potentially pre-cancerous; left untreated, they may turn into a type of cancer called squamous cell carcinoma. Untreated lesions have up to a 20% risk of progression to squamous cell carcinoma, so treatment by a dermatologist is recommended.. Dermoscopy can frequently help differentiate LPLK from other lesions; however, it does not help differentiate most pink or skin colored LPLK lesions from basal cell carcinoma and melanoma because these pink lesions tend to be devoid of any dermoscopic structures (structureless or featureless lesions). To complicate matters, LPLK often reveal crystalline structures, which can also be seen in basal cell carcinoma and melanoma. With that being said, the key dermoscopic features of LPLK are as follows:
Diffuse granular pattern:
This is characterized by the presence of diffuse granularityThis glossary term has not yet been described. (peppering) of brown, grey, bluish-grey, or white grey colors. These granules tend to be coarse are scattered throughout the lesion in a homogenous fashion.
Localized granular pattern:
The presence of grayish-brown granularity (peppering) localized to one focal area within the lesion. Since the regressionThis glossary term has not yet been described. is only occurring in a part of the lesion, the typical dermoscopy features of the original lesion (seborrheic keratosis, solar lentigo, actinic keratosis) can still be found. The coarse granules in LPLK can be confused with the multiple bluegrey dots (also known as regression structures) seen in melanomas. One differentiating feature, however, is the size of the granules. In LPLK, the granules tend to be larger, coarser, and often appear clumped. In contrast, in melanoma, the blue-grey dots are much smaller and finer in size.