Dermoscopy of inflammatory skin diseases

From dermoscopedia

The basic principles of applying dermoscopy in inflammatory diseases are the following: 1. Interpretation of dermoscopic findings should be always context-driven. The diagnosis in dermatology is usually established on the basis of the clinical morphology and distribution of the skin eruption. Sometimes, the clinical manifestations do not allow the establishment of a definite diagnosis and more than 1 diseases are included in the differential diagnosis. Applying dermoscopy and interpreting dermoscopic findings makes sense only within this specific differential diagnosis that has been established clinically.

2. The main parameters that have to be evaluated when applying dermoscopy in general dermatology are the following: i) Vessels morphology ii) Vessels distribution iii) Scale color iv) Scale distribution v) Follicular criteria vi) Pigmented structures vii) Specific clues

3.The selection of equipment that preserves vessels’ morphology is essential because vascular structures represent the most important group of criteria in diagnosing inflammatory skin diseases.[1] Evaluation of vascular structures should be performed with a second-generation hand-held dermatoscope using polarized light. If only a standard dermatoscope requiring direct contact is available, ultrasound gel and an examination with only applying minimal pressure may prevent the alteration or disappearance of vascular structures. Similar if acquiring a dermoscopic image, it is preferable to use new-generation dermatoscopes instead of contact-dermatoscopes for inflammatory lesions.

Dermoscopic criteria of inflammatory skin diseases.jpg


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.[2] The term “red globules” has also been used to describe the same dermoscopic feature. [3] Distinction between dots and globules is based on the diameter of the structure (dots are smaller), and it is important in dermoscopy of melanocytic tumors. In psoriasis, both terms may be used, since the roundish vascular structures can be of various diameters, although they are usually of similar size within a given lesion. Under higher magnifications (x100-x400), the psoriatic vessels appear as dilated, elongated, and convoluted capillaries.[4] Histopathologically, red dots correspond to the loops of vertically arranged vessels within the elongated dermal papillae. Important for differential diagnosis, 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.[2] Scales removal will bring to light the characteristic vascular pattern of psoriasis, possibly together with tiny red blood drops, which can be characterized as the dermoscopic “Auspitz sign”. A specific feature for the diagnosis of psoriasis is the sign of red globular rings, described by Vazquez-Lopez et al. If present, the red globules are arranged in irregular circles or rings. But even if highly specific, this sign is only seen in a minority of psoriatic lesions. Other types of vessels distribution are extremely rare in psoriasis.[2] [5] In addition, light red background color and white superficial scales are two common dermoscopic criteria of plaque psoriasis. In differential diagnosis of erythematosquamous dermatoses, scale color is of particular value: Yellow scales are a negative predictor of plaque psoriasis, therefore argueing for the presence of dermatitis. [2] 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. Contrariwise, in scalp or palmoplantar psoriasis, thick hyperkeratotic plaques hide the typical vascular structures, which may be recognized after removal of the scales.[6]

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.[7]


Despite their variable etiopathologies, all forms of dermatitis show similar histopathologic just as similar dermoscopic characteristics. Dermatitis usually exhibits red dots in a patchy distribution and yellow scales.[2] 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.[2]

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. [2] Belonging to the group of the characteristic yellow scales, the “yellow clod sign” is frequently observed in nummular eczema.[8] Notably, yellow scale color is dermoscopically detected not only in acute, but also in chronic dermatitis. Contact dermatitis, nummular eczema, generalized dermatitis, chronic dermatitis, seborrheic dermatitis and other subtypes were reported to reveal similar findings in dermoscopy, but further investigation on their specific pattern is needed.[2][9][10]

Lichen planus

White crossing streaks (Wickham striae) are the hallmark of lichen planus not only in clinical examination (particularly in mucous lesions), but also in dermoscopy.[3][11] White crossing streaks are a specific, as well as a constant finding for lichen planus, irrespectively of lesion’s duration or subtype.[12] Vessels of mixed morphology (dotted and linear) may be found at the periphery of the lesion.

Pityriasis rosea

The two major dermoscopic features of pityriasis rosea are yellowish 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 lacks the characteristic regular distribution of psoriasis.[13] [14]

Pityriasis rubra pilaris

Whitish keratotic plugs and linear vessels either solely or mixed with dotted vessels on a yellowish background are the most frequent dermoscopic features reported for pityriasis rubra pilaris.[15] This observation suggests that pityriasis rubra pilaris shows no typical characteristics of psoriasis, which is the most common differential diagnosis. [16] [15] [17]


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’’).[18][19][20][21] In disseminated superficial actinic porokeratosis, the peripheral track may be hyperpigmented.[22] [23][24] 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.[25][26] 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.[27][28]

Sarcoidosis and lupus vulgaris

In sarcoidosis [25] and lupus vulgaris[29], 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.[30]

Granuloma annulare

Granuloma anulare may reveal a high variability of dermoscopic findings. Vessels may be dotted, short linear or linear arborizing, while background color displays various combinations of red, white and yellow. In certain cases, pigmented structures may be detected. 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.[28]

Necrobiosis lipoidica

Necrobiosis lipoidica exhibits a characteristic and repetitive pattern, typified by a prominent network of linear arborizing vessels and a yellow background color. The prominent vascular network of necrobiosis lipoidica represent the most valuable feature for differential diagnosis from other granulomatous diseases.[31][27] 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.[28] Ulcerations and yellow crusts represent the most common additional features.[31]

Discoid lupus erythematosus

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.[32] 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.[29]


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.[33] 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

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.[34] [35] In morphea, linear vessels within the lilac ring are a typical finding in dermoscopy.[9] By dermoscopical examination, lichen sclerosus is typified by comedo-like openings and whitish patches, whereas morphea exhibits fibrotic beams.[36]

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.[37] On the contrary, urticarial vasculitis dermoscopically exhibit purpuric dots or globules on an orange-brown background.[38] Both diseases reveal no highly specific criteria, but the presence of purpuric dots is suggestive of an underlying vasculitis.

Pigmented purpuric dermatoses

The term pigmented purpuric dermatoses comprehends the following entities: Schamberg’s disease, Majocchi purpura, eczematoid purpura of Doucas and Kapetanakis, lichen aureus and pigmented purpuric lichenoid dermatitis of Gougerot-Blum. Pigmented purpuric dermatoses are dermoscopically identified by the combination of purpuric dots or globules and orange-brown areas of pigmentation.[39][40] A similar dermoscopic pattern has been described in patients with mycosis fungoides, supporting previous evidence reporting clinical and histopathologic overlap between the two entities.[10] Since the pigmented purpuric dermatoses and mycosis fungoides notably differ in physical course and management, lesions showing a dermsocopic pattern of pigmented purpuric dermatoses should be evaluated carefully.

Darier’s disease

In Darier’s disease, dermoscopical analysis highlights the characteristic pseudocomedones and therefore is an effective additional tool for its clinical recognition. Vascular patterns are unspecific, comprising erythema, dotted and linear vessels.[41]


For cutaneous mastocytosis four dermoscopic patterns have been defined: light-brown blot, pigment network, reticular vascular pattern, and yellow-orange blot. [42] [43] Dermoscopic pattern varies depending on the subtype [43]: 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.


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.[44] In granuloma faciale, the specific dermoscopic features are dilated follicular openings, perifollicular whitish halo, follicular keratotic plugs and linear branching vessels. Clinically, granuloma faciale has to be differentiated from sarcoidosis, discoid lupus erythematosus, lupus vulgaris, lymphoma and basal cell carcinoma. The mentioned dermoscopic patterns simplify clinical differential diagnosis. But the distinction from discoid lupus erythematosus, which exhibits similar findings, remains challenging.[45]

Mycosis fungoides

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). In the assessment of a chronic lesion previously diagnosed as dermatitis, dermoscopic examination is expected to reveal dotted vessels, occasionally combined with yellowish scales. Lesions under long-term treatment with topical steroids represent the only exception to this rule. When, instead, dermoscopy reveals linear vessels, the suspicion of mycosis fungoides rises strongly and in this case, patient’s management should be adjusted accordingly.[10]

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