Inflammoscopy

0.00

(0 votes)

→ cite chapter  → become an author   version history • page credits

Annotations
Description	This chapter describes dermoscopy of inflammatory diseases
Author(s)	N. N.
Responsible author	N. N. → send e-mail
Status	open
Status update	March 25, 2023
Status by	Ralph Braun

Glossary:Lichen planus, Glossary:Psoriasis, Glossary:Dermatitis, Glossary:Porokeratosis, Glossary:Discoid lupus, Glossary:Pityriasis rubra pilaris Cite:08-Inflammoscopy Message:08-Inflammoscopy Participate:08-Inflammoscopy

User=

Selection of the optimal equipment

In inflammatory and infectious diseases, the main histopathologic alterations are usually not associated with pigment, but include cellular infiltrations, vascular structures and alterations of the thickness or the anatomy of the epidermis. Therefore, the selection of an equipment that preserves vessels’ morphology and enhances their optimal visualization is much more crucial when evaluating skin eruptions than tumors. The non-polarized hand-held dermatoscopes require direct contact of the optical lens to the skin surface, which may result in alteration of the morphology, or even disappearance, of the underlying vascular structures. The polarized hand-held dermatoscopes, not requiring contact to the skin, offers a better projection of vascular structures and allows the visualisation of white shiny structures, which are hardly, or not at all, seen with non-polarized light. In conclusion, we strongly advice the use of non-contact polarised dermatoscopes when applying dermoscopy in general dermatology.

Main categories of dermoscopic criteria

The most frequent structures seen in inflammatory skin diseases are vessels, scales or crusts and criteria associated to the hair follicle. Therefore, the most important parameters to be evaluated when dermoscopically examining skin eruptions are the following:

Morphology of vessels

We propose a simplified categorisation when applying dermoscopy in general dermatology

1. Dotted vessels. This category includes roundish vessels of any size, without discriminating among pinpoint, dotted and globular vessels, which anyhow differ only in the diameter. Dotted vessels can be seen in the majority of the common inflammatory skin diseases, including dermatitis (all types), lichen planus, pityriasis rosea, porokeratosis et al.
2. Linear vessels, not curved and without branches. Linear vessels are very frequently present in sun-damaged skin. They are also seen in lesions of any disease treated with topical steroids for long periods. The most frequent skin disease characterised by linear vessels is rosacea, which is typified by a specific arrangement the vessels in polygons (polygonal vessels).
3. Linear vessels with branches. They are somehow similar to the typical vessels seen in basal cell carcinoma. They can be seen in granulomatous skin diseases (sarcoidosis, tuberculosis) and at the late stage of discoid lupus erythematosus.
4. Linear curved vessels. They are similar to the so-called comma vessels that are frequently seen in dermal nevi. They can be found in lichen planus, granulomatous disorders and also in mycosis fungoides

Distribution of vessels

1. Regular. This means that the vascular structures are equally and homogeneously distributed all over the surface of the lesion. This vascular arrangement typifies psoriasis.
2. Peripheral. Vascular structures are distributed mainly at the peripheral part of the lesion. This arrangement is frequently seen in lichen planus.
3. Patchy. The vascular structures are arranged randomly without following any specific pattern. It is also called asymmetric or unspecific distribution. It can be seen in many diseases, such as dermatitis and pityriasis rosea.
4. In plexus. The vascular structures form a kind of network. This arrangement can be seen in psoriasis (dotted vessels) and is also very characteristic of rosacea (linear vessels).

Color of scales

1. White. This is the most frequent scale colour and can be found in most of the erythematosquamous and papulosquamous skin diseases, such as psoriasis or lichen planus.
2. Yellow. Yellow crusts are a result of serum extravasation and yellow scales a result of serum mixed with keratin. Yellow crusts and scales represent the dermoscopic hallmark of all types of dermatitis, corresponding histopathologically to the underlying spongiosis.

Distribution of scales

1. Diffuse. Scales covering all the surfaces of the lesion. It cannot be considered specific of any diagnosis, since diffuse scales can be seen in several hyperkeratotic dermatoses.
2. Central. Scales accentuated in the centre of the lesion. Again, this scaling pattern cannot be considered as specific, although it is quite frequently seen in psoriasis.
3. Peripheral. Scales sparing the center and distributed mainly at the periphery. It is a classic sign of pityriasis rosea, but can also be seen in tinea corporis and other entities.
4. Patchy. Random and asymmetric distribution of scales. May be seen in several diseases.

Follicular criteria

1. Follicular plugs. Keratin plugs of white or yellow color filling the follicular openings. It can be found in several diseases, but is considered as the dermoscopic hallmark of early stage discoid lupus erythematous
2. Perifollicular white halo. A white-colored circle surrounding each hair follicle and/or filling the space between follicles. It might correspond either to perifollicular fibrosis (ex. discoid lupus erythematosus) or to epidermal hyperplasia (ex. hypertrophic lichen planus).
3. Perifollicular pigmentation. Pigment accentuated around the hair follicles. It can be seen in some alopecias, but also represents the first sign of re-pigmentation in vitiligo.
4. Follicular depigmentation. Loss of pigment in the hair follicles, as compared to the surrounding skin. It represents an early sign of active vitiligo, but can also be found in other causes of hypopigmentation.

Specific clues

Specific clue is considered a feature that, when present, is very strongly suggestive of one only diagnosis. Specific clues have been suggested for several diseases, but only a few have been investigated in appropriately designed studies that included control groups. Examples of specific clues are the white crossing lines of lichen planus (Wickham striae) and the peripheral keratotic rim of porokeratosis.

Psoriasis

caption text

Dotted vessels represent the most frequent dermoscopic feature of psoriasis, being present in every single psoriatic plaque. Detection of any other morphologic type of vessels excludes the diagnosis of PP.

caption text

The uniform distribution of the red dots within the lesion represents the dermoscopic hallmark of psoriasis. Dotted vessels may be detected in several inflammatory dermatoses, but no other disease exhibits the symmetrical and homogenous arrangement of vessels all over the lesion that characterizes psoriatic plaques, unless thick superficial scales cover them. Scales removal will bring to light the characteristic vascular pattern of psoriasis, possibly together with tiny red blood drops (“Auspitz sign”). A specific feature for the diagnosis of psoriasis is the sign of red globular rings. If present, the red globules are arranged in irregular circles or rings, the sign is highly specific, but it is only seen in a minority of psoriatic lesions. Other types of vessels distribution are extremely rare in psoriasis. In addition, light red background color and white superficial scales are two common dermoscopic criteria of plaque psoriasis. Yellow scales are a negative predictor of plaque psoriasis, therefore argueing for the presence of dermatitis. Dermoscopic findings of psoriasis may vary dependent of the body site and the various amounts of scaling. In psoriatic balanitis and inverse psoriasis lesions that lack scaling, the regularly distributed red dots are prominent. In scalp or palmoplantar psoriasis, thick hyperkeratotic plaques hide the typical vascular structures, which may be recognized after removal of the scales.

Dermoscopic transformation of psoriatic plaques under treatment

Regular dermoscopic examination is of avail in patients under treatment with topical steroids or systemic biological agents, because additional morphologic information might be helpful for early detection of a relapse. Additionally, steroid-induced skin atrophy is earlier detected by dermoscopy (by revealing characteristic linear vessels) than in the clinical setting.

Dermatitis

caption text

Dermatitis usually exhibits red dots in a patchy distribution and yellow scales. The red dots are identical to the vessels in psoriatic lesions, but unlike psoriasis, their distribution is not homogenous and regular, but rather clustered, generating an irregular, “patchy” pattern.

Superficial scaling is a frequent characteristic of dermatitis, but opposed to psoriasis and other erythematosquamous skin diseases, the scales in dermoscopy of dermatitis reveal a yellow color either alone, or in combination with white. The “yellow clod sign” is frequently observed in nummular eczema. Notably, yellow scale color is dermoscopically detected not only in acute, but also in chronic dermatitis.

Lichen planus

caption text

White crossing streaks (Wickham striae) are the hallmark of lichen planus not only in clinical examination (particularly in mucous lesions), but also in dermoscopy. White crossing streaks are a specific, as well as a constant finding for lichen planus, irrespectively of lesion’s duration or subtype. Vessels of mixed morphology (dotted and linear) may be found at the periphery of the lesion.

Pityriasis rosea

caption text

The two major dermoscopic features of pityriasis rosea are yellowish-red background color and peripheral whitish scales. Besides, dotted vessels may be detected in dermoscopy of most pytiriasis rosea lesions, as seen in psoriasis and dermatitis. However, the vascular pattern is arranged randomly and it lacks the characteristic regular distribution of psoriasis.

Pityriasis rubra pilaris

caption text

Yellowish areas mixed with dotted and linear are the most frequent dermoscopic features reported for pityriasis rubra pilaris, moreover central keratin plugs may also be observed. This observation suggests that pityriasis rubra pilaris shows no typical characteristics of psoriasis, which is the most common differential diagnosis.

Porokeratosis

caption text

In porokeratosis, the cornoid lamella, known as the histopathologic hallmark of porokeratosis, is revealed by dermoscopic examination as a well-defined, white-yellowish peripheral annular structure (“white track”, ‘‘the outlines of a volcanic crater as observed from a high point’’).

In disseminated superficial actinic porokeratosis, the peripheral track may be hyperpigmented. Depending on the disease subtype and the stage of progression, the central part of porokeratotic lesions can demonstrate a brownish pigmentation, dotted or linear vessels, or a structureless whitish area. By dermoscopy, the diagnosis of porokeratosis is performed without difficulty, even in clinically atypical cases.

Granulomatous skin diseases

In dermoscopy, the presence of orange-yellowish globules or areas and linear vessels are highly suggestive of dermal granulomas and therefore easily allows the diagnosis of granulomatous skin diseases. However, their differential diagnosis remains challenging due to identical dermoscopic presentation produced by several causes. Notably, the plaque form of cutaneous sarcoidosis may resemble necrobiosis lipoidica. The longer and more branching telangiectasias of necrobiosis lipoidica, caused by atrophic changes not present in cutaneous sarcoidosis, were reported to be an important feature for discrimination from other granulomatous diseases.

Sarcoidosis and lupus vulgaris

caption text

In sarcoidosis and lupus vulgaris, orange-yellowish translucent globular-like or structureless areas in combination with linear vessels have been described, which are suggested to correspond to the underlying granulomas.

Cutaneous leishmaniasis

In cutaneous leishmaniasis, dermoscopy reveals generalized erythema, yellow tears (follicular plugs), hyperkeratosis and central erosion/ulceration. The characteristic translucent orange-yellowish color of sarcoidosis may additionally be present.

Granuloma annulare

caption text

Vessels may be dotted, short linear or linear arborizing, while background color displays various combinations of red, white and yellow. Pigmented structures may be detected sometimes. The observation that granuloma anulare rarely exhibits features of other granulomatous skin diseases, such as necrobiosis lipoidica or sarcoidosis, might help clinicians rule out the latter conditions.

Necrobiosis lipoidica

caption text

Necrobiosis lipoidica pattern is typified by well-focused vessels and a yellowish-orangish background. The arborizing vessels of necrobiosis lipoidica represent the most valuable feature for differential diagnosis from other granulomatous diseases. This typical vascular morphology should be differentiated from the classical ‘arborizing' vessels of nodular-cystic basal cell carcinoma. Classical arborizing vessels usually reveal ramifications into finest capillaries, while vessels in necrobiosis lipoidica exhibit only few diameter variegations and reveal multiple anastomosing ramifications.

Discoid lupus erythematosus

caption text

Dermoscopic criterias differ depending on the stage of progression of discoid lupus erythematosus. In early lesions, perifollicular whitish halo, follicular plugging and white scales are the predominant features, while in longer-standing lesions telangiectatic vessels, pigmentation structures and whitish structureless areas prevail. This distinct dermoscopic pattern is useful for discriminating discoid lupus erythematosus from lupus pernio (cutaneous sarcoidosis) and lupus vulgaris (cutaneous tuberculosis). The latter diseases lack the predominant follicular abnormalities of discoid lupus erythematosus, and display a characteristic pattern consisting of orange-yellowish areas/globules and branching arborizing vessels.

Rosacea

caption text

Rosacea is characterized by a unique dermoscopic vascular pattern of polygonal vessels. Since this pattern of dermoscopic vascular polygons is not present in any other skin disease, this is a sensitive criterion for the diagnosis of rosacea. Regarding the accuracy in evaluation of vascular alterations by dermoscopy, the technique may be additionally useful for follow up of rosacea. Additional dermoscopic findings of rosacea include follicular plugs, white scales, features related to the presence of demodex (“demodex tails”) and whitish amorphic follicular material. However, the frequency of these additional criteria is relatively low. In papulopustular rosacea, clinically non-visible pustules provide a useful dermoscopic clue for discrimination from lupus erythematosus, but this requires further investigation.

Lichen sclerosus and morphea

caption text

The predominant dermoscopic feature of lichen sclerosus are white-yellowish structureless areas, independently of the location. Genital lichen sclerosus commonly appear with linear vessels while extragenital lesions rather exhibit keratotic plugs, surrounded by an erythematous halo. This halo represents a marker of disease activity. In morphea, linear vessels within the lilac ring are a typical finding in dermoscopy. By dermoscopical examination, lichen sclerosus is typified by comedo-like openings and whitish patches, whereas morphea exhibits fibrotic beams.

Urticaria and urticarial vasculitis

Common urticaria is dermoscopically characterized by a red, reticular network of linear vessels, which may be surrounded by an area devoid of vessels, corresponding to dermal edema. On the contrary, urticarial vasculitis dermoscopically exhibit purpuric dots or globules on an orange-brown background. Both diseases reveal no highly specific criteria, but the presence of purpuric dots is suggestive of an underlying vasculitis.

Pigmented purpuric dermatoses

caption text

Pigmented purpuric dermatoses are dermoscopically identified by the combination of purpuric dots or globules and orange-brown areas of pigmentation. A similar dermoscopic pattern has been described in patients with mycosis fungoides, supporting previous evidence reporting clinical and histopathologic overlap between the two entities. Lesions showing a dermoscopic pattern of pigmented purpuric dermatoses should be evaluated carefully.

Darier’s disease

caption text

In Darier’s disease, dermoscopical analysis highlights the characteristic central star-shaped/branched polygonal/roundish-oval brownish area surrounded by a whitish halo.. Other relevant findings are pseudocomedones. Vascular patterns are unspecific, including erythema, dotted and linear vessels.

Mastocytosis

For cutaneous mastocytosis four dermoscopic patterns have been defined: light-brown blot, pigment network, reticular vascular pattern, and yellow-orange blot. Dermoscopic pattern varies depending on the subtype : In maculopapular mastocytosis, light-brown blot and pigment network predominate. In solitary mastocytoma, a yellow orange blot is typical. In all cases of telangiectasia macularis eruptiva perstans, a reticular vascular pattern is present. The reticular pattern of the vessels is even proved associated with an increased risk of need for daily use of anti-mediator medication. Therefore, dermoscopy in combination with other variables could provide additional help in the identification of patients at risk for more severe symptoms.

Vasculitides

Scarce evidence exists on the dermoscopic pattern of vasculitides. Henoch-Schonlein purpura has been shown to dermoscopically reveal irregularly shaped red patches with blurred borders. Reported findings of urticarial vasculitis are described above. In granuloma faciale, the specific dermoscopic features are dilated follicular openings, perifollicular whitish halo, follicular keratotic plugs and linear branching vessels over a pinkish background.

Mycosis fungoides

caption text

Even if being a neoplastic disease, mycosis fungoides is listed in this article as a major differential diagnosis from several inflammatory skin disorders. In particular, differentiation between chronic dermatitis and early stage mycosis fungoides is often highly problematic. In dermoscopical studies, significant differences have been shown: in contrast to the dotted vessels in dermatitis, mycosis fungoides reveal short linear vessels and orange-yellowish areas. In addition, in mycosis fungoides a peculiar vascular structure is frequently observed consisting of a dotted and a linear component (spermatozoon-like structure).

References