Version May 2024
INTRODUCTION — A wide variety of cutaneous and systemic disorders present with annular (ring-like) skin lesions (table 1). The careful assessment of lesion characteristics and accompanying clinical features is valuable for narrowing the differential diagnosis.
Diagnostic clues for the identification of disorders that present with annular lesions will be reviewed here. Greater detail on many of the disorders discussed below is available elsewhere in UpToDate.
DEFINITION — Annular skin lesions are figurate lesions characterized by a ring-like morphology. Although plaques represent the most common presentation of annular lesions, lesions may also be macular, nodular, or composed of grouped papules, vesicles, or pustules.
Additional terms that are frequently used to describe the characteristics of annular lesions include:
●Arcuate – Consists of arc-shaped lesions that represent incompletely formed annular lesions (picture 1).
●Polycyclic – Exhibits multiple coalescing arcuate or annular lesions (picture 2A-B).
●Target/targetoid – Demonstrates a dusky red center surrounded by a zone of pallor, which in turn is surrounded by a peripheral erythematous ring (a characteristic feature of erythema multiforme) (picture 3A-B).
●Atypical target – Lacks full criteria for target lesions; only two zones of color change are present (picture 4).
PATIENT ASSESSMENT — The identification of the underlying diagnosis in patients with annular lesions begins with the assessment of several factors. The clinician should consider the following points during the skin examination:
●What are additional physical characteristics of the lesions?
●Are the lesions stationary, expanding, or migratory?
●Where are the lesions located?
●Are there associated systemic or cutaneous signs or symptoms?
If the diagnosis is not apparent after these questions have been answered, additional studies may be considered (see 'Diagnostic tests' below). A table of disorders that may present with annular features and their clinical and pathologic features is provided (table 1).
In some disorders, such as tinea corporis and erythema annulare centrifugum, annular lesions represent the most common clinical presentation. In contrast, other disorders may demonstrate annular lesions only as an occasional or incidental feature. For example, annular lesions are not a classic feature of psoriasis, nummular dermatitis, seborrheic dermatitis, secondary syphilis, sarcoidosis, mycosis fungoides, or malignant skin tumors, but occasionally occur in the context of these diseases. A distinct annular variant of lichen planus has been reported [1].
The concomitant detection of features that are more typical of a particular skin disease can be of value in the diagnosis of annular lesions in conditions in which this morphology is not common. As an example, the identification of classic psoriatic plaques on the scalp or signs of psoriatic nail disease may lead to the inclusion of psoriasis into the differential diagnosis for a scaly and erythematous annular lesion.
Lesion characteristics
Color — Lesion color can be useful for narrowing the differential diagnosis. The vast majority of annular lesions represent inflammatory processes, and thus, manifest with blanchable cutaneous erythema. Of note, in patients with dark skin pigmentation, this erythema may be difficult to appreciate.
Acute inflammatory lesions often present with bright erythema (picture 5A-C). In contrast, erythema tends to be muted in lesions of granuloma annulare, a disorder characterized by annular plaques that persist for months to years (picture 6A-C).
Lesion color may also be influenced by disorder-specific characteristics. Lesions of acute or chronic urticaria characteristically have a pink color that results from the combination of dermal edema and vascular dilation (picture 7A-B). Moreover, a dusky red to violaceous color, which is often seen in the setting of epidermal necrosis, is a common feature in lesions of erythema multiforme (picture 3B). (See "Granuloma annulare: Epidemiology, clinical manifestations, and diagnosis", section on 'Clinical features' and "New-onset urticaria", section on 'Clinical manifestations' and "Erythema multiforme: Pathogenesis, clinical features, and diagnosis", section on 'Clinical manifestations'.)
The color of lesions may shift with lesion age. As acute inflammatory lesions resolve, erythema may become less prominent. Postinflammatory hyperpigmentation, when present, may be the only remnant of resolved lesions.
Scale — The presence, absence, and quality of scale are key diagnostic features for several annular dermatoses. When a rim of fine scale is present, the clinician should take note of whether it is "leading" (present at the advancing edge), or "trailing" (present more centrally):
●Leading scale – The prototypical annular inflammatory skin lesion with leading scale is the dermatophyte infection tinea corporis (picture 5A, 5D). Single or multiple lesions may be present. An uncommon fungal infection, tinea imbricata, presents with concentric, scaly rings (picture 8A-B). (See "Dermatophyte (tinea) infections", section on 'Tinea corporis' and "Dermatophyte (tinea) infections", section on 'Tinea imbricata'.)
●Trailing scale – Trailing scale is most commonly seen in pityriasis rosea and superficial erythema annulare centrifugum:
•Pityriasis rosea – Patients with pityriasis rosea typically present with numerous oval erythematous thin plaques on the trunk and proximal extremities. The long axis of the oval is arranged along lines of skin tension. On the back, this classically results in a "Christmas tree-like" distribution. The scale is typically described as a collarette (picture 9). A larger, oval, erythematous plaque (herald patch) occurs as the initial sign of disease in 50 percent or more of patients. (See "Pityriasis rosea".)
•Superficial erythema annulare centrifugum – Erythema annulare centrifugum is an inflammatory reactive disorder that occurs in both superficial and deep forms. Patients present with single or multiple annular or arcuate erythematous plaques on the face, neck, trunk, or extremities. Trailing scale is a characteristic feature of the superficial form (picture 5B, 5E). In contrast, scale is typically absent in the deep variant of the disease. The cause of the disorder is often unknown; infections and medications are among the possible triggers [2]. An association with malignancy, particularly hematologic, is termed "paraneoplastic erythema annulare centrifugum eruption" (PEACE) [3]. (See "Erythema annulare centrifugum".)
In addition, a very thin, palpable rim of ribbon-like scale known as a cornoid lamella is a pathognomonic feature of lesions of porokeratosis (picture 10A-B). These lesions also have a distinct histopathologic appearance (picture 11). The absence of scale is a relevant feature for granuloma annulare, distinguishing these lesions from the more prevalent diagnosis of tinea corporis. Granuloma annulare presents as single or multiple papules or plaques that exhibit a dull, erythematous color and tend to be slightly firm and smooth to palpation (picture 6A-C). (See "Porokeratosis" and "Granuloma annulare: Epidemiology, clinical manifestations, and diagnosis".)
Vesicles or pustules — Linear IgA dermatosis is an autoimmune subepidermal blistering disorder that may be triggered by medications (particularly vancomycin) [4]. It classically presents with annular clusters of tense vesicles and bullae in a "string of jewels" pattern (picture 12). In the early stages of the condition, the vesicles may be tiny, few in number, and located on an annular erythematous, edematous base. Linear IgA dermatosis may be idiopathic or drug induced. When it occurs in children, the term chronic bullous dermatosis of childhood is also used to describe this condition. (See "Linear IgA bullous dermatosis".)
Flaccid pustules coalescing into annular, polycyclic, or serpiginous configurations are typical of subcorneal pustular dermatosis (also known as Sneddon-Wilkinson disease) (picture 13A-B). Intertriginous areas, skin flexures, and the abdomen are preferred sites of involvement. (See "Subcorneal pustular dermatosis".)
Neutrophilic figurate erythema typically begins with a target-like, erythematous papule that expands to an annular, erythematous patch with vesicles or purpura. It has histologic features similar to other neutrophilic dermatoses with a lesser degree of inflammation [5].
Purpura — Purpura results from the extravasation of erythrocytes from cutaneous vessels. Examples of disorders that characteristically present with purpuric annular lesions include:
●Purpura annularis telangiectodes of Majocchi – Purpura annularis telangiectodes of Majocchi is a subtype of pigmented purpuric dermatosis [6]. Patients present with symmetric, asymptomatic eruptions of pinpoint nonblanchable red to red-brown macules that coalesce to form annular patches (picture 14). The most common site of involvement is the lower extremity. Mycosis fungoides (a form of cutaneous T cell lymphoma) can present with lesions with similar features and should be considered in the differential diagnosis in patients with extensive or chronic involvement. (See "Pigmented purpuric dermatoses (capillaritis)", section on 'Purpura annularis telangiectodes (Majocchi disease)'.)
●Acute hemorrhagic edema of infancy – Acute hemorrhagic edema of infancy is a benign small vessel vasculitis that is characterized by edematous urticarial plaques that progress to purpuric plaques that often have a targetoid appearance (picture 15) [7]. Lesions are primarily distributed on the head, genitals, and distal extremities. Fever may be present, but patients typically do not appear toxic. Children under the age of two represent the population that is usually affected. (See "IgA vasculitis (Henoch-Schönlein purpura): Clinical manifestations and diagnosis", section on 'Differential diagnosis'.)
●Immunoglobulin A vasculitis (Henoch-Schönlein purpura) – Immunoglobulin A vasculitis (Henoch-Schönlein purpura) is an IgA-mediated small vessel vasculitis that occurs in children and adults. Cutaneous features include symmetric palpable purpura that are predominantly distributed in dependent regions (picture 16). Some lesions may have an annular appearance. Systemic involvement can occur, including renal failure. (See "IgA vasculitis (Henoch-Schönlein purpura): Clinical manifestations and diagnosis".)
●Traumatic purpura – Trauma may lead to annular purpuric or ecchymotic lesions on the skin. Skin injury sustained during participation in paintball, a sport that involves shooting nonlethal capsules at other players, is a classic example. Teenagers are common participants in this activity. The impact of the paintball capsule on the skin typically results in an annular purpuric lesion that persists for one to two weeks (picture 17). Suction purpura from the Chinese practice of "cupping" or romantic liaisons may be annular. In general, the diagnosis of traumatic purpura is facilitated by the patient history.
●Urticarial vasculitis – Urticarial vasculitis is another disorder in which purpura may occur in the setting of annular lesions. (See 'Symptoms' below.)
●Dependent purpura in annular inflammatory disorders – Purpura on the lower legs or other dependent areas are common secondary occurrences in nonpurpuric inflammatory disorders. The purpura develop as a result of vascular leakage. This is particularly common in serum sickness-like eruptions in children (picture 5G) (see 'Expanding lesions' below). The most prominent purpura are usually located in areas with the highest hydrostatic forces (eg, lower legs), as blood extravasation is most likely to occur in those sites.
Symptoms — Most annular eruptions are either asymptomatic or mildly to moderately pruritic, and knowledge of associated symptoms may be useful for supporting the diagnosis of specific diseases.
A less commonly observed feature that occurs fairly frequently in urticarial vasculitis is the presence of burning or painful sensations in addition to pruritus. Lesions of urticarial vasculitis often look identical to classic urticaria (edematous pink wheals), but frequently persist beyond 24 hours and may be associated with residual bruising or hyperpigmentation (picture 18A-B) [8]. Such features should prompt consideration for urticarial vasculitis in patients who present with urticarial lesions. Urticarial vasculitis may occur in association with autoimmune diseases, medications, injections, and malignancy. (See "Urticarial vasculitis".)
Annular and polycyclic lesions associated with focal anesthesia or motor neuropathy may be seen in patients with leprosy. (See "Leprosy: Epidemiology, microbiology, clinical manifestations, and diagnosis", section on 'Clinical manifestations and diagnosis'.)
Lesion progression — Several disorders are characterized by transient or migratory features, and asking patients about lesion expansion, lesion migration, and lesion time course can be useful for diagnosis.
Expanding lesions — Outward spread of individual annular lesions is commonly noted in tinea corporis, granuloma annulare, erythema chronicum migrans, and erythema annulare centrifugum. Lesions progressively advance into areas of previously uninvolved tissue, resulting in a progressive increase in size:
●Tinea corporis – Lesions of tinea corporis expand slowly over the course of weeks as the fungal infection spreads outward, often leaving central clearing (picture 5A, 5D). (See "Dermatophyte (tinea) infections", section on 'Tinea corporis'.)
●Erythema migrans – The hallmark feature of early localized Lyme disease is erythema migrans. A set of concentric erythematous rings appears 7 to 14 days after tick detachment and progressively enlarges to form a lesion that is usually at least 5 cm in diameter (picture 19A-B). Lesions may demonstrate a "bulls-eye" appearance, and last approximately four weeks if untreated [9]. In patients with early disseminated Lyme disease, multiple annular lesions may be present (picture 20). (See "Clinical manifestations of Lyme disease in adults".)
The clinical appearance of erythema migrans is indistinguishable from that of the skin findings of southern tick-associated rash illness (STARI); however, the different endemic areas of the vectors assist with diagnosis. (See "Southern tick-associated rash illness (STARI)".)
●Granuloma annulare – In contrast to the fairly rapid outward spread of erythema migrans, lesions of granuloma annulare expand slowly over the course of weeks to months. Solitary or multiple annular plaques with a firm border are seen (picture 6A-C). Lesions are commonly found on distal extremities. (See "Granuloma annulare: Epidemiology, clinical manifestations, and diagnosis".)
●Erythema annulare centrifugum – The annular erythematous scaly or nonscaly plaques of erythema annulare centrifugum tend to expand over the course of days to weeks (picture 5B, 5E). (See 'Scale' above.)
●Serum sickness-like reactions – Serum sickness-like reactions occur due to a variety of medications (most commonly antibiotics [7]) and are most frequently seen in children. Symptoms begin one to three weeks after initiation of the offending agent. (See "Serum sickness and serum sickness-like reactions".)
Patients with serum sickness-like reactions usually present with urticarial lesions that start in the flexures and then become generalized (picture 5C, 5F-G). These eruptions are frequently initially mistaken for acute urticaria, but in contrast to acute urticaria, individual lesions remain for greater than 24 hours. The skin lesions typically gradually expand, leaving central clearing or central faint purpura, which are usually most evident on the abdomen or lower legs. Affected patients commonly also develop fever, arthralgias, and erythematous and edematous hands and feet.
●Erythema gyratum repens – Erythema gyratum repens is a rare, often paraneoplastic eruption characterized by concentric polycyclic, annular, and circinate red plaques that give a characteristic "wood grain" appearance (picture 21A-C). (See "Cutaneous manifestations of internal malignancy", section on 'Erythema gyratum repens'.)
●Erythema papulatum centrifugum (EPC) – EPC, also known as erythema papulosa semicircularis recidivans, is an annular, eczematous eruption that primarily has been described in Japanese and Chinese males. Patients present with tiny, grouped papules on the trunk that spontaneously resolve but frequently relapse. EPC is characterized by histologic evidence of perieccrine inflammation [10].
●Delayed localized hypersensitivity reaction – Pruritic, painful, edematous, large, pink plaques have been described in recipients of coronavirus disease 2019 (COVID-19) vaccination in the site of inoculation. This has been dubbed "COVID arm" [11]. (See "COVID-19: Allergic reactions to SARS-CoV-2 vaccines", section on 'Late local reactions'.)
Migratory or transient lesions — Migratory or transient lesions are characteristic of urticaria, urticaria multiforme, erythema marginatum, eosinophilic annular erythema, and annular erythema of infancy:
●Urticaria – Although an outbreak of urticaria may last days to weeks or more, a hallmark feature of urticaria is that the individual erythematous, edematous plaques last less than 24 hours (picture 7A-C). Marking a few lesions with a pen can be useful for confirming the transient nature in patients with numerous lesions. (See "New-onset urticaria" and "Chronic spontaneous urticaria: Clinical manifestations, diagnosis, pathogenesis, and natural history".)
●Urticaria multiforme (acute annular urticaria) – Urticaria multiforme, also known as acute annular urticaria, is a self-limited urticarial hypersensitivity eruption that primarily occurs in infants and very young children [12,13]. Lesions appear on the face, trunk, and extremities as annular erythematous plaques with central clearing or dusky blue centers. Unlike serum sickness-like reactions and erythema multiforme, the duration of individual lesions does not exceed 24 hours. Myalgias and arthralgias are absent. Pruritus is typically present. Other associated findings may include angioedema of the face or acral areas, dermatographism, and low-grade fever. Viral or bacterial infections, antibiotics, and vaccinations have been proposed as potential triggers. The disorder is treated with antihistamines and discontinuation of a triggering medication, if present.
●Erythema marginatum – The migratory, polycyclic, and nonpruritic erythematous plaques of erythema marginatum typically migrate within minutes to hours (picture 2A, 2C). These annular lesions tend to have a thin border and often display arciform, polycyclic, and other incompletely formed annular lesions. Erythema marginatum occurs in association with rheumatic fever due to group A streptococcal infection. (See "Acute rheumatic fever: Clinical manifestations and diagnosis".)
●Eosinophilic annular erythema – Eosinophilic annular erythema is a rare disorder that presents with recurrent, annular or gyrate, often asymptomatic erythematous plaques on the trunk and extremities [14-16]. Both children and adults may be affected. A hypersensitivity reaction to an unknown antigen has been proposed as an inciting factor for eosinophilic annular erythema; however, the cause of the condition remains unknown [14]. Histopathologic examination of lesional tissue typically reveals a dense perivascular and interstitial lymphocytic infiltrate with many eosinophils. Although some authors have proposed that eosinophilic annular erythema may be a subtype of eosinophilic cellulitis (Wells syndrome) [15,17], the relationship between these disorders remains unclear. Responses to antimalarials or systemic glucocorticoids have been reported; however, the condition also may spontaneously resolve over months to years [14]. (See "Eosinophil biology and causes of eosinophilia", section on 'Disorders with eosinophilic involvement of specific organs'.)
●Annular erythema of infancy – Annular erythema of infancy is a rare disorder of young children characterized by the development of inflamed papules that evolve into enlarging, annular plaques that may coalesce into polycyclic lesions [18]. The disorder most often occurs in children under the age of one year and often has a generalized distribution. Pruritus or scale may be present or absent. Histopathologic examination reveals a superficial and deep, lymphohistiocytic infiltrate with eosinophils [18]. Annular erythema of infancy is a transient disorder that usually resolves spontaneously within days to a few weeks.
Lesion location — The location of annular skin lesions can offer clues for diagnosis. Disorders that frequently present with photodistributed, acral, or genital lesions are reviewed below.
Photodistributed — Photoexacerbated dermatoses tend to occur on sites that are not typically covered by clothing or other adornments such as the balding scalp, forehead, dorsal nose, zygomatic cheeks, posterolateral neck, upper chest, extensor upper extremities, and shins. On the face, the shadow areas of the orbital rim, chin, and nasolabial folds are often spared:
●Lupus erythematosus – Lupus erythematosus is the most common cause of annular lesions in a photodistributed arrangement. Subacute cutaneous lupus erythematosus, tumid lupus erythematosus, and neonatal lupus erythematosus may present with such features:
•Subacute cutaneous lupus erythematosus – Subacute cutaneous lupus erythematosus often presents with annular erythematous scaly plaques (picture 22) [19]. Scaling at the borders of lesions is common. The neck, upper trunk, and arms are typical sites of involvement. (See "Overview of cutaneous lupus erythematosus", section on 'Subacute cutaneous lupus erythematosus'.)
•Lupus erythematosus tumidus – Lupus erythematosus tumidus features smooth, raised, fixed erythematous plaques (picture 23). Lesions may be annular with central clearing or solid plaques. Scale is uncommon.
•Neonatal lupus erythematosus – Neonatal lupus erythematosus is a self-limited condition that results from transplacental transmission of maternal SSA/Ro, SSB/La, or U1RNP antibodies. These infants present with annular, scaly red plaques on the face, arms, or trunk that are triggered by ultraviolet light (picture 24). Diagnosis should prompt evaluation for cardiac manifestations. (See "Neonatal lupus: Epidemiology, pathogenesis, clinical manifestations, and diagnosis".)
●Actinic lichen planus – Photodistributed annular lesions are also a common manifestation of actinic lichen planus (lichen planus actinicus), an idiopathic condition that most commonly occurs in dark-skinned young adults in subtropical climates [1]. Individuals of Middle Eastern descent appear to be most susceptible. Patients present with annular hyperpigmented plaques (picture 25A-B).
●Annular elastolytic giant cell granuloma – Annular elastolytic giant cell granuloma is characterized by annular red plaques with raised borders and an atrophic center and is typically found on sun-exposed skin (picture 26A-B). It closely resembles granuloma annulare and can be differentiated histopathologically. (See "Granuloma annulare: Epidemiology, clinical manifestations, and diagnosis", section on 'Differential diagnosis'.)
Acral — The palms and soles are often spared in generalized eruptions such as urticaria. In contrast, the target or atypical target lesions of erythema multiforme have a predilection for these and other acral sites. Target lesions of erythema multiforme classically demonstrate a dusky red center, surrounded by a zone of pallor, which is in turn surrounded by a peripheral erythematous ring (picture 3A-C). Patients often have a history of oral or genital herpes simplex virus infection. (See "Erythema multiforme: Pathogenesis, clinical features, and diagnosis".)
The dorsal hands and feet are common sites for the nonscaly, erythematous plaques of granuloma annulare (picture 6A-C). (See "Granuloma annulare: Epidemiology, clinical manifestations, and diagnosis".)
Acral and periarticular skin are the most common sites of erythema elevatum diutinum, an unusual form of cutaneous small vessel vasculitis, which may present with annular, dull red to violaceous plaques. (See "Erythema elevatum diutinum".)
Genital
●Erythema multiforme – Erythema multiforme may involve the genitals with either typical target lesions or atypical target lesions that do not include all three color zones (picture 27) (see 'Definition' above). Approximately 20 percent of patients with recurrent erythema multiforme have genital involvement [20]. (See "Erythema multiforme: Pathogenesis, clinical features, and diagnosis".)
●Circinate balanitis – Circinate balanitis associated with reactive arthritis is characterized by serpiginous lesions on the glans penis that may take on an arcuate or annular appearance (picture 28A-B). Conjunctivitis, urethritis, and palmoplantar hyperkeratosis (keratoderma blennorrhagicum) are additional features of reactive arthritis. (See "Reactive arthritis".)
●Annular lichen planus – Annular lichen planus may involve the male genitalia or other body sites (picture 29A-B) [21].
●Syphilis – Secondary syphilis may present with annular, scaly plaques on the penis, face (particularly at the corners of the mouth), legs, and feet [22]. (See "Syphilis: Epidemiology, pathophysiology, and clinical manifestations in patients without HIV".)
Intertriginous — Intertriginous eruptions localize to the flexures (neck, axilla, inguinal folds, inframammary folds, and gluteal cleft):
●Annular lichenoid dermatitis of youth – Annular lichenoid dermatitis of youth typically features smooth, annular, red plaques on the groin or flanks in young people. The histopathology reveals a lichenoid infiltrate with apoptotic cells in the tips of the rete ridges with a polyclonal infiltrate [23].
●Subcorneal pustular dermatosis – Subcorneal pustular dermatosis is characterized by asymptomatic, chronic, recurrent crops of small pustules in annular, arcuate, or serpiginous configurations in intertriginous regions. (See "Subcorneal pustular dermatosis".)
●Reactive granulomatous dermatitis – "Reactive granulomatous dermatitis" is a term that encompasses palisaded neutrophilic granulomatous dermatitis, interstitial granulomatous dermatitis, and interstitial granulomatous drug reaction. These conditions often present with granuloma annulare-like eruptions and may be associated with systemic disease, such as autoimmune diseases, infections, and malignancy. Classically, interstitial granulomatous dermatitis is characterized by linear, "cord-like" eruptions on the trunk. Other variants are recognized, including an annular form that may occur on the proximal limbs or intertriginous areas [24]. (See "Palisaded neutrophilic and granulomatous dermatitis".)
FEBRILE PATIENTS — Several diagnoses should be considered in febrile patients with annular skin lesions:
●Acute febrile neutrophilic dermatosis (Sweet syndrome) – Patients with acute febrile neutrophilic dermatosis present with an abrupt onset of red, well-demarcated, tender, and often annular plaques accompanied by fever and leukocytosis (picture 30A-B). The cutaneous lesions often demonstrate an edematous, almost vesicular (pseudovesicular) appearance, and are typically located on the upper body. Associated factors include inflammatory bowel disease, malignancy, infections, and medications [25]. (See "Sweet syndrome (acute febrile neutrophilic dermatosis): Pathogenesis, clinical manifestations, and diagnosis".)
●Serum sickness-like reaction – Patients with serum sickness-like reactions frequently present with fever. (See 'Expanding lesions' above.)
The possibility of the following disorders also should be considered in febrile children:
●Acute hemorrhagic edema of infancy – This disorder presents as annular purpuric edematous plaques in young children (picture 15). (See 'Purpura' above.)
●Kawasaki disease – Kawasaki disease is a self-limited vasculitis of childhood that presents with fever, conjunctivitis, mucositis, acral edema, lymphadenopathy, and an exanthematous skin eruption. Occasionally, the cutaneous eruption of Kawasaki disease manifests as an annular or targetoid eruption (picture 31) [26]. (See "Kawasaki disease: Clinical features and diagnosis".)
●CANDLE syndrome – Chronic atypical neutrophilic disorder with lipodystrophy and elevated temperature (CANDLE) syndrome is an autoinflammatory disorder due to mutations in PSMB8. Patients typically present with early-onset fever and generalized, annular violaceous plaques as well as other systemic findings associated with chronic inflammation [27]. (See "Autoinflammatory diseases mediated by interferon production and signaling (interferonopathies)", section on 'CANDLE'.)
DIAGNOSTIC TESTS — If after a careful history (including a thorough chronologic drug history) and physical examination, the diagnosis of an annular skin eruption remains unclear, select diagnostic studies may be helpful (table 1). As noted above, circling lesions with a pen or marker can be useful for identifying the migratory nature of certain disorders. (See 'Migratory or transient lesions' above.)
Examples of scenarios in which additional studies can be of value are below:
●Scaly annular eruption – Potassium hydroxide preparation (KOH) is instrumental in diagnosing or ruling out tinea corporis (picture 32). (See "Office-based dermatologic diagnostic procedures", section on 'Potassium hydroxide preparation'.)
●Photodistributed annular eruption – Antinuclear antibody (ANA) testing and skin biopsy can be useful for confirming a diagnosis of cutaneous lupus erythematosus. (See "Overview of cutaneous lupus erythematosus".)
●Target or atypical target lesions – Herpes simplex virus (HSV) is a common trigger of erythema multiforme. If lesions suspicious for active HSV infection are present in a patient with erythema multiforme, the performance of Tzanck smears, direct fluorescent antibody preparations, viral cultures, or PCR studies on specimens taken from the site of suspected HSV infection may be used to confirm the presence of the virus. (See "Erythema multiforme: Pathogenesis, clinical features, and diagnosis", section on 'Diagnosis'.)
●Migratory, serpiginous eruption – In patients with symptoms or signs suggestive for rheumatic fever, throat cultures, rapid streptococcal antigen tests, and antistreptolysin O antibody titers are confirmatory tests for streptococcal pharyngitis, the most common inciting factor for acute rheumatic fever. (See "Acute rheumatic fever: Clinical manifestations and diagnosis", section on 'Diagnosis'.)
Other laboratory tests may be performed based upon suspicion of the underlying disorder.
Skin biopsy — Skin biopsy is always an option when the diagnosis is uncertain. It is most useful when the disorders being considered have different histopathologic findings (table 1). A 4 mm punch biopsy from the active edge of an annular lesion is generally preferred over a shave biopsy, as it allows for evaluation of the full thickness of the epidermis and dermis. (See "Skin biopsy techniques", section on 'Punch biopsy'.)
EMPIRICAL DIAGNOSIS OF TINEA CORPORIS — If performing a KOH is not feasible prior to treatment in a patient who presents with lesions suspicious for tinea corporis, empirical therapy with a topical antifungal agent with activity against dermatophytes (eg, azole antifungals, ciclopirox, or terbinafine) is reasonable, due to the relatively high prevalence of tinea corporis and the low risk for adverse effects of topical agents. Combination products containing antifungal agents and potent corticosteroids (eg, betamethasone dipropionate with clotrimazole, Lotrisone) should be avoided, as the corticosteroid component may exacerbate tinea and cause cutaneous atrophy. A recurrence or a failure of presumed tinea corporis to resolve after treatment may indicate inadequate treatment, reinfection (from autoinoculation or an external source), or an incorrect diagnosis. (See "Dermatophyte (tinea) infections", section on 'Tinea corporis'.)
INDICATIONS FOR REFERRAL — Urgent dermatologic consultation should be performed if the underlying diagnosis is uncertain in systemically ill patients with inflammatory annular lesions. The acute illness or an underlying systemic disorder may be associated with significant morbidity (eg, immunoglobulin A vasculitis [Henoch-Schönlein purpura], acute rheumatic fever, systemic lupus erythematosus, etc).
Infants with annular eruptions should have prompt dermatology referral because of the potential for morbidity even in the absence of obvious signs of systemic illness. As examples, untreated neonatal lupus and immunoglobulin A vasculitis (Henoch-Schönlein purpura) may have serious long-term sequelae.
INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5th to 6th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.
Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)
●Basics topic (see "Patient education: Granuloma annulare (The Basics)")
SUMMARY AND RECOMMENDATIONS
●Overview – Annular skin lesions are characterized by a ring-like morphology. Annular lesions are common in skin disease, and occur in the setting of a variety of disorders (table 1). (See 'Definition' above.)
●Patient assessment – The identification of associated clinical features is often useful for the diagnosis of annular lesions. Physical characteristics such as lesion color and the presence or absence of scale, vesicles, or pustules can be quickly assessed. Other factors to consider include the course of lesion progression, lesion location, and associated cutaneous or systemic symptoms. (See 'Patient assessment' above.)
●Diagnostic tests – If the diagnosis remains uncertain after the patient history and physical examination, diagnostic studies such as potassium hydroxide (KOH) preparations to evaluate for tinea corporis, skin biopsies, and select laboratory studies based upon clinical suspicion of the underlying diagnosis can be useful. (See 'Diagnostic tests' above.)
●Empirical diagnosis of tinea corporis – Whenever feasible the diagnosis of tinea corporis should be confirmed with a KOH preparation prior to treatment. If it is not possible to perform a KOH preparation, empirical treatment with a topical antifungal agent may be prescribed. Combined antifungal and potent corticosteroid agents should not be used. (See 'Empirical diagnosis of tinea corporis' above.)
●Indications for referral – Serious systemic disorders may present with inflammatory annular lesions. Urgent dermatologic consultation should be obtained if the diagnosis remains uncertain in patients who are systemically ill. (See 'Indications for referral' above.)
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