Seborrheic Keratosis Including Lichen Planus-Like Keratosis V.6 Robert Johr
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Chapter V6 Seborrheic Keratosis Including Lichen Planus-like Keratosis V.6 Robert Johr Contents V.6.2 Clinical Features V.6.1 Definition . 313 “Warty” and “stuck-on” are adjectives used to V.6.2 Clinical Features . 313 describe these ubiquitous epidermal skin neo- V.6.3 Dermoscopic Criteria. 315 plasms. Characterizations which are not always apparent clinically. V.6.4 Relevant Clinical Differential Most people develop at least one seborrheic Diagnosis. 319 keratosis in their lifetime, usually forming V.6.5 Histopathology. .322 de novo in adults and the elderly. They can also be found in the teens, twenties, and thirties. The V.6.6 Management. .323 number varies from less than 20 in the average V.6.7 Lichen Planus-like Keratosis. 323 person to hundreds of lesions that slowly in- V.6.7.1 Definition . .323 crease in size and number with age. Usually de- V.6.7.2 Clinical Features . .323 veloping on any skin surface except the palms, V.6.7.3 Dermoscopy. .323 soles, mucous membranes, or sun-exposed ar- V.6.7.4 Relevant Clinical Differential eas (Fig. V.6.1) seborrheic keratosis can be skin Diagnosis. 325 colored, tan and various shades of brown, V.6.7.5 Histopathology. .325 alarmingly black, or multicolored. They are V.6.7.6 Management. .326 well-circumscribed round-to-oval macules, papules, and nodules, most often plaques rang- References. .327 ing in size from a few millimeters to centime- ters. The borders can also be irregular and notched with unusual distributions such as along skin-cleavage lines, around the areola, or in a raindrop distribution [1] on the backs of the elderly. The surface can be scaly, crusty, smooth, or greasy (Fig. V.6.2). Most people have many vari- ations on the theme of the possible clinical pre- sentations, and individual seborrheic keratosis can have a combination of clinical characteris- V.6.1 Definition tics. Rough-surfaced lesions can be brittle and crumble into pieces when picked, leaving a raw Along with melanocytic nevi, seborrheic kera- red moist surface. In intertriginous areas espe- tosis is the most common benign cutaneous cially under the breasts, they can be moist, red, neoplasm. The pathogenesis is unknown. There and without scales. Follicular plugs and tiny is a strikingly familiar predisposition probably white, yellow, or dark horn pearls can be seen with an autosomal–dominant inheritance pat- embedded in the surface. The correlation with tern. the dermoscopic criteria of comedo-like open- 314 R. Johr ings and milia-like cysts aids in the clinical di- agnosis before dermoscopy is performed. Stuccokeratosis and dermatosis papulosa nigra are two very common variants of sebor- rheic keratosis. Located on the ankles and feet, stuccokeratosis are numerous small whitish scaly papules typically found in older adults. Dermatosis papulosa nigra is seen in adult dark- er-skinned races and consists of multiple hyper- pigmented soft papules that are often peduncu- lated. They can also be found on the neck and upper trunk. The majority of seborrheic keratosis are as- Fig. V.6.1. This is a typical older patient with multiple ymptomatic, yet they can become sore or pru- seborrheic keratoses that do not develop where there is ritic either spontaneously, or secondary to trau- no sun exposure. Seborrheic keratosis could be sun-in- ma from patient manipulation, articles of duced lesions Fig. V.6.2. Typical scaly, crusty, and seborrheic keratosis that is easily diagnosed clinically V.6 Seborrheic Keratosis Chapter V.6 315 Fig. V.6.3. This irritated seborrheic keratosis lacks the clinical and dermoscopic criteria to make the diagnosis. Histopathological evaluation should be considered clothing, or physical activity. Inflammation can have metastatic disease; however, its recognition be mild, moderate, or severe with edema, ery- can facilitate the early diagnosis of occult ma- thema of the surrounding skin, thick scale, fri- lignancy. Often paralleling the course of the un- able crust formation, oozing, and bleeding. derlying malignancy, it can improve with suc- When severe, the typical clinical characteristics cessful surgery or chemotherapy, and it can are obliterated, and the inflamed seborrheic worsen if the malignancy returns. The sign of keratosis might be indistinguishable from a Leser–Trelat has also been associated with preg- pyogenic granuloma and, if dark, from nodular nancy, heart-transplant recipients, following melanoma (Fig. V.6.3). Another manifestation chemotherapy, in human immunodeficiency vi- of inflammation is the Meyerson phenomenon rus infection, and following erythrodermic pso- with a halo of eczematization surrounding the riasis or drug eruptions. If a clinician makes lesion. Spontaneous regression is not a common this diagnosis, a comprehensive systemic work- occurrence. up is indicated [2–8]. The sudden development, inflammation, or regression of multiple seborrheic keratoses is a clinical scenario that can be a cutaneous mani- V.6.3 Dermoscopic Criteria festation of internal malignancy. It is called the sign of Leser–Trelat. If it is associated with other Most, but not all, seborrheic keratoses can be di- paraneoplastic skin findings, such as acanthosis agnosed clinically or with dermoscopy. A small nigricans, acquired icthyosis, or the develop- percentage require histopathology. Global pat- ment of lanugo hair, it is even more worrisome. terns and local criteria often require a differential The average age of onset is 61 years, and the diagnosis. The gold standard of histopathology most common malignancy is adenocarcinoma, might not be straightforward with collision le- especially of the stomach. Other malignancies sions when seborrheic keratosis is associated with associated with the sign of Leser–Trelat include different benign or malignant pathology. Com- lymphoma, mycosis fungoides, Sezary syn- munication between the dermoscopist and der- drome, leukemia, and cancer of the lung, breast, matopathologist is essential when there is asym- pancreas, and esophagus. Most patients already metrical presentation of dermoscopic criteria. 316 R. Johr Fig. V.6.4. In this seborrheic keratosis the milia-like cysts light up like “stars in the sky.” There are also several pigmented round and oval comedo-like openings. The dark blotch of color has a differential diagnosis that includes a collision-tumor possible melanoma Fig. V.6.5. Are the circular whitish structures the milia- like cysts of a seborrheic keratosis or the appendigeal openings of lentigo maligna? The general dermoscopic principle “if in doubt, cut it out” led to the diagnosis of lentigo maligna that was surrounded by seborrheic keratosis (arrow) The original algorithm used to diagnose seb- asymmetry of color and structure, plus the mul- orrheic keratosis included two classic criteria: ticomponent global pattern with three or more milia-like cysts and comedo-like openings. Ad- distinct areas of dermoscopic criteria as seen in ditional criteria are now used to help make the melanomas. No single criterion by itself is diag- diagnosis [9, 10]. Sharp demarcation and abrupt nostic, and as many criteria as possible should V.6 cut-off of pigmentation and dermoscopic crite- be identified and evaluated before the dermo- ria are routinely seen. There can be significant scopic diagnosis is made. There are innumerable Seborrheic Keratosis Chapter V.6 317 Fig. V.6.6. This well-demar- cated lesion has multiple, ir- regularly shaped comedo-like openings plus a few subtle whitish milia-like cysts. Im- portant dermoscopic criteria are not always easy to find combinations and appearances of what can be ance (Fig. V.6.6). Histopathologically, they rep- seen including black, various shades of brown, resent keratin filled dilated follicular openings gray, red, white, blue, and yellow colors. in the epidermis, black-head like structures. Milia-like cysts (pseudocysts, pseudohorn They can be indistinguishable from the dots cysts, “stars in the sky”) are single or multiple and globules used to diagnose melanocytic le- variously sized and irregular distributed round sions (Fig. V.6.7). Clonal seborrheic keratosis white or yellowish structures that histopatho- lacking the stereotypical dermoscopic criteria logically represent intraepithelial horn cysts. can have small dark-brown or black globular- They can be opaque and dull or appear to light like structures similar to those seen in benign up like “stars in the sky” (Fig. V.6.4). Usually melanocytic lesions and melanoma, or larger small, they can be large and irregular in shape. ovoid nests that are often seen in basal cell car- It is most important to differentiate milia-like cinomas [11, 12]. Pressure and side-to-side cysts from the appendigeal openings of the movement with instrumentation will only pseudonetwork seen on the head and neck so change the shape of comedo-like openings. that lentigo maligna is not misdiagnosed as a Multiple comedo-like openings favor the diag- seborrheic keratosis (Fig. V.6.5). Even experi- nosis of seborrheic keratosis; however, they can enced dermoscopists cannot always make the also be seen in melanocytic nevi and occasion- distinction. Multiple or large milia-like cysts fa- ally in melanoma. A recent history of change vor the diagnosis of a seborrheic keratosis. might be the only reason to excise a lesion that When a few in number, they can also be seen in clinically looks like a seborrheic keratosis and benign melanocytic nevi and occasionally in has multiple comedo-like openings typically melanomas. seen in seborrheic keratosis but with subtle der- Comedo-like openings (pseudofollicular moscopic criteria that diagnoses a melanoma openings, follicular openings, irregular crypts, (melanoma incognito) [13]. keratin plugs) present as variously sized, Fissures and ridges (brain-like pattern) are a roundish, oval, or irregularly shaped sharply global pattern commonly found in seborrheic circumscribed single or multiple yellowish, keratosis. They are formed by dark-brown or brown, or black crater-like openings that can black linear and branching depressions creating have a targetoid or three-dimensional appear- a network or cerebriform pattern resembling 318 R.