Utility of IL-36 immunostaining in distinguishing psoriasis from pityriasis rosea and pityriasis lichenoides.

BACKGROUND: Psoriasis is an inflammatory skin disease driven by upregulation of cytokines in the Th17 pathway, including interleukin-36 (IL-36). Previous studies have highlighted the utility of IL-36 immunostaining for psoriasis compared to spongiotic dermatitis and other psoriasiform dermatoses; however, no study has examined the role of IL-36 staining in distinguishing psoriasis from pityriasis rosea (PR) and pityriasis lichenoides (PL), known histologic mimickers of psoriasis. METHODS: We compared the immunostaining pattern of IL-36 for 21 PR cases, 22 PL cases, and 10 psoriasis cases. We graded the immunostaining as 0, negative; 1, focal weak; 2, diffuse weak; 3, focal, strong; or 4, diffuse strong. We further categorized stains as negative (0-2 score) or positive (3-4 score) and utilized Fisher's exact test to compare the immunostaining pattern of these entities. RESULTS: All psoriasis specimens were positive for IL-36, whereas all PR specimens were negative (p = 0.00000002). Twenty PL specimens were negative (p = 0.000001). Nine of 10 pityriasis lichenoides et varioliformis acuta cases were negative (p = 0.00012), and 11 of 12 cases of pityriasis lichenoides chronica were negative (p = 0.00003). CONCLUSIONS: Our findings highlight the potential role of IL-36 immunostaining in distinguishing psoriasis from other psoriasiform dermatoses, including PR and PL.

Clinicopathologic features of pityriasis rosea-like drug eruption secondary to imatinib: A case report and review of the literature.

Pityriasis rosea is an acute, self-limited exanthem that typically occurs in adolescence and young adulthood, classically featuring ovoid erythematous and scaly lesions on the trunk and proximal extremities. While its cause is not definitively known, the classic form of pityriasis rosea may result from the reactivation of latent human herpesvirus (HHV) infections (HHV-6 and HHV-7). Interestingly, drug eruptions that clinically and/or histopathologically resemble pityriasis rosea have also been reported. These pityriasis rosea-like drug eruptions tend to occur at an older age and have a shorter duration than the classic type. As there are different management paradigms, the distinction between classic pityriasis rosea and the mimicking drug eruption is important to recognize. Herein, we report a case of a pityriasis rosea-like drug eruption that occurred in association with imatinib mesylate treatment for chronic myeloid leukemia. We also review the clinicopathologic features of reported cases of pityriasis rosea-like drug eruption, including those due to imatinib. While the clinical morphology of the cutaneous drug-related eruption mimics the lesions seen in classic pityriasis rosea, the presence of unique histopathologic findings, including necrotic keratinocytes, interface dermatitis, and eosinophils, may aid in distinction.

Pityriasis Rosea in Kaduna, North-West Nigeria: A 20-Year Experience.

BACKGROUND: Pityriasis rosea (PR) is an acute, self-limiting papulosquamous skin disease which predominantly affects children and young adults. Pityriasis rosea appears to be more common in West Africa. Reports about PR from northern Nigeria are few. OBJECTIVES: To present the relative prevalence, demographic and clinical characteristics of PR. METHODS: We conducted a retrospective review of records of consecutive patients attending two dermatology clinics in Kaduna, North-West Nigeria between September 2001 and November 2021. RESULTS: Of 39,037 patients, 922 (2.4%) presented with PR: Median age was 15 years (range 3 months to 63 years) and 24% < 10 years, 60% < 18 years, 87% < 30% years. 62% were female. In patients < 20 years, males were significantly more in number than females (69.6% vs. 60.9%, P = 0.007) while in those >20 years, females were more in number (39.1% vs. 30.4%, P = 0.007). The mean duration of disease at presentation was 14 days (range 1 - 240 days). Majority (60%) were seen during the rainy season. A herald patch was present in 67.8%, usually occurring 7 days before the main rash. The trunk was affected by the main rash in 94% while the neck and face were affected in 19.2% and 23.6%, respectively. Itching was reported by 80%. The classic disease constituted 80.2%. Oral involvement was rare. CONCLUSION: Pityriasis rosea is a common disease in Kaduna. It mostly affects children, adolescents and young adults. Clinical presentation is typical in the majority of patients. Rarely an atypical disease occurs. Oral involvement was rare.

CONTEXTE: Le pityriasis rosé (PR) est une dermatose papulosquameuse aiguë spontanément résolutive qui touche principalement les enfants et les jeunes adultes. Le pityriasis rosea semble être plus courant en Afrique de l'Ouest. Les rapports sur la RP du nord du Nigeria sont peu nombreux. OBJECTIFS: Présenter la prévalence relative, les caractéristiques démographiques et cliniques de la RP. METHODES: Nous avons effectué un examen rétrospectif des dossiers de patients consécutifs fréquentant deux cliniques de dermatologie à Kaduna, dans le nord-ouest du Nigeria, entre septembre 2001 et novembre 2021. RESULTATS: Sur 39 037 patients, 922 (2,4 %) ont présenté une RP : l'âge médian était de 15 ans (intervalle de 3 mois à 63 ans) et 24 % < 10 ans, 60 % < 18 ans, 87 % < 30 % ans. 62 % étaient des femmes. Chez les patients de < 20 ans, les hommes étaient significativement plus nombreux que les femmes (69,6 % contre 60,9 %, P = 0,007) tandis que chez ceux de > 20 ans, les femmes étaient plus nombreuses (39,1 % contre 30,4 %, P = 0,007) . La durée moyenne de la maladie au moment de la présentation était de 14 jours (fourchette de 1 à 240 jours). La majorité (60%) ont été observées pendant la saison des pluies. Un patch annonciateur était présent chez 67,8%, survenant généralement 7 jours avant l'éruption principale. Le tronc était touché par l'éruption principale dans 94 % tandis que le cou et le visage étaient touchés dans 19,2 % et 23,6 %, respectivement. Des démangeaisons ont été signalées par 80 %. La maladie classique constituait 80,2 %. L'atteinte orale était rare. CONCLUSION: Le pityriasis rosé est une maladie courante à Kaduna. Elle touche principalement les enfants, les adolescents et les jeunes adultes. La présentation clinique est typique chez la majorité des patients. Rarement une maladie atypique survient. L'atteinte orale était rare. Mots clés: Pityriasis rosé, Kaduna-Nigeria, Épidémiologie, Présentation clinique, Africains.

Impact of COVID-19 on Clinicopathological Spectrum of Pityriasis Rosea in Korea.

BACKGROUND: Pityriasis rosea (PR) is a papulosquamous eruption with generally unknown origin but suspected to be related to viral etiologies. The clinicopathological spectrum of several disorders with viral etiologies has been altered after the coronavirus disease 2019 (COVID-19) pandemic. The author group could experience coherent histological alterations in PR after the COVID-19 pandemic. This study aimed to investigate how the clinicopathological findings of PR were changed after the COVID-19 pandemic. METHODS: Patients (n = 11) diagnosed with PR based on the clinical manifestations and skin biopsies between February 2018 and October 2019 and 11 patients in February 2020 and October 2021 were retrospectively analyzed by investigating the medical records. RESULTS: The patients with PR during the COVID-19 pandemic demonstrated statistically significant histopathological alterations from classic brisk and dense infiltration pattern to dormant and sparse infiltration and psoriasiform-dominant patterns (P = 0.019). PR was associated with more frequent pruritus during the pandemic period (P = 0.027). CONCLUSION: In conclusion, PR demonstrated a significant histopathological alteration with more frequent pruritus during the COVID-19 pandemic. The comparative results about clinicopathological findings of PR will provide a useful reference for dermatologists in the diagnostic process of PR in the COVID-19 pandemic.

Pityriasis Rosea-like eruptions following COVID-19 mRNA-1273 vaccination: A case report and literature review.

Pityriasis rosea (PR) is a self-limited disease with exanthematous papulosquamous rashes mostly associated with reactivation of human herpesvirus (HHV)-6 or HHV-7. PR-like eruptions, which occur along with peripheral eosinophilia, interface dermatitis, and eosinophils on histopathology, may result from medications or vaccinations. Previously, PR-like eruptions had been noted following vaccination for influenza or other vaccines. During this pandemic, acute COVID-19 infection has been related to PR or PR-like eruptions in several cases. Various COVID-19 vaccines associated with PR-like eruptions were rarely reported. Herein, we report a case of cutaneous PR-like eruptions following COVID-19 mRNA-1273 vaccination.

Pityriasis rosea in pregnancy: A case series and literature review.

BACKGROUND AND OBJECTIVE: Pityriasis rosea (PR), a common skin disease in young adults, may adversely affects the course of pregnancy and the unborn child. PATIENTS AND METHODS: Data from forty-six pregnant women with PR seen in the dermatological university clinic between 2003 and 2018 were analyzed and compared with patient data (n = 53) from previously published studies to determine the incidence and risk factors for an unfavorable pregnancy outcome after PR infection. RESULTS: Unfavorable pregnancy outcomes (defined as miscarriage, preterm delivery before week 37 of gestation, or birth weight < 2,500 g) were significantly less frequent in our study population than in a pooled cohort obtained from previously published studies (10.9 % vs. 39.6 %; P = 0.0012). Analysis of pooled data from our study and from previous studies revealed that the week of pregnancy at onset of PR was inversely associated with an unfavorable outcome (odds ratio [OR] = 0.937; 95 % CI 0.883 to 0.993). In addition, duration of PR (OR = 1.432; 95 % CI 1.129 to 1.827), additional extracutaneous symptoms (OR = 4.112; 95 % CI 1.580 to 10.23), and widespread rash distribution (OR 5.203, 95 % CI 1.702 to 14.89) were directly associated with unfavorable outcome. CONCLUSION: In most cases, PR does not influence pregnancy or birth outcomes.

Pigmented purpuric dermatosis: Ten years of experience in a tertiary hospital and awareness of mycosis fungoides in differential diagnosis.

BACKGROUND: Pigmented purpuric dermatoses (PPD) can clinically mimic many diseases. Histopathology provides a definitive diagnosis. The aim of the study is to reveal the features of patients with PPD and to determine the disease frequency in the differential diagnosis, especially mycosis fungoides (MF). METHODS: We retrospectively reviewed records of patients with PPD admitted to our hospital from January 2010 to May 2019. We studied the histopathological features of 127 patients, and performed pattern analysis on cases with a confirmed histopathologic diagnosis of PPD. Among the cases presenting with clinical features of PPD, but displaying different histopathological diagnoses, we focused on MF and tried to clarify the features of PPD-like MF. RESULTS: Overall, 389 patients were admitted to our hospital with PPD symptoms. Of them, 262 patients were diagnosed clinically and a histopathological examination was performed in 127 patients. Of 127, 87 were diagnosed with PPD, and in the remaining 40, non-specific features (9.4%), vasculitis (6.2%), pityriasis rosea (4.7%), MF (3.9%), suspected-MF (1.5%), and other dermatoses (%5.5) were detected. The biopsy findings of two patients showed PPD, but during follow-up, the diagnosis of MF was established. CONCLUSIONS: MF should be included in the differential diagnosis of PPD cases presenting with longstanding and widespread involvement.

Pityriasis rosea-like cutaneous eruption as a possible dermatological manifestation after Oxford-AstraZeneca vaccine: Case report and brief literature review.

Pityriasis rosea (PR) has been manifested in patients suffering from COVID-19 as well as after vaccine protocols against SARS-CoV-2. It has a possible association with the HHV-6B virus (roseola infantum) and can be controlled by antivirals such as acyclovir as well as by the amino acid l-Lysine that showed a positive result in reducing the number of lesions and healing time. The aim of this study was to report a case of PR after a second dose of Oxford-AstraZeneca, the adopted therapy and a brief literature review. A 53-year-old woman, phototype II, presented an erythematous lesion in the posterior right thigh 15 days after the second dose of Oxford-AstraZeneca vaccine. Eight days after the initial injury, new injuries appeared in the calf, buttocks and thighs. The diagnosis was PR with a 5-week eruption cycle. The treatment consisted of the use of l-Lysine, 3 grams loading dose and 500 mg for 30 days and moisturizing/healing lotion, starting 14 days after the herald patch. After the 5th week of the disease cycle, there were no new eruptions and the repair cycle continued for up to 8 weeks leaving some residual skin spots. It is concluded that the patient may be a carrier a latent virus, HHV-6, and the vaccine administration with immune system stimulation, would have activated the possible virus causing PR. l-Lysine helped to control the manifestation by limiting the number of lesions and their location, which were restricted to the legs, thighs and buttocks.

L-lysine therapy to control the clinical evolution of pityriasis rosea: Clinical case report and literature review.

Pityriasis rosea (PR) is a dermatological disease with an erythemato-papulosquamous manifestation, distributed on the trunk and extremities affecting healthy people, especially children and young people between 10 and 35 years of age. The evolution is 6 to 8 weeks and may remain for 3 to 6 months. It regresses spontaneously and can leave changes in the skin color but reversibly. Acyclovir is indicated to minimize clinical manifestations with the suspected of viral association (HHV-6 and 7). Another group of the human herpesvirus family (HHV-1 and 2), causes herpes simplex that is controlled with the antivirals, including acyclovir, as well as the amino acid L-lysine, both showing positive and similar results in reducing the number of annual manifestations and the healing time of the lesions. The aim of this study is to report a case of PR in a child, to review the literature on the etiopathogenesis of the disease and on the effects of L-lysine as well as another amino acid in the treatment. An 11-year-old girl, phototype II, presented lesions diagnosed as PR. The cycle would be 6 to 8 weeks on average. A solution of L-lysine was prescribed for 30 days, on an empty stomach. After the fourth day of therapy, the cycle of new eruptions was interrupted, initial lesions regressed, accelerating the repair of larger lesions resulting in an improvement of the clinical condition. We concluded that the administration of L-lysine, in therapeutic doses, can be a safe alternative for the PR control.

Dermoscopic characterization of guttate psoriasis, pityriasis rosea, and pityriasis lichenoides chronica in dark skin phototypes: An observational study.

Dermoscopy as a diagnostic tool is attaining impetus in inflammatory dermatoses with the cumulative description of characteristic findings in most dermatoses obviating at times the need of biopsy. In this retrospective observational study, 20 histopathology confirmed cases each of pityriasis rosea (PR), guttate psoriasis (GP), and pityriasis lichenoides chronica (PLC) seen over a period of 3 years were included. Dermoscopy images were extracted from photography archives for evaluation and three lesions from each patient (60 lesions each) were analyzed. Comparison of dermoscopy characters was done among PR, GP, and PLC in pairs using chi-square test and a P-value of less than .05 was considered significant. Most common background color in PR (86.7%) and PLC (96.7%) was yellow to yellow-orange and in GP was dull red to pink (70%). Vessels were visualized in all lesions of GP and most characteristic pattern was regular (93.3%), dotted vessels (95%). In PR 63.3% lesions had dotted vessels mostly in a patchy distribution (56.7%). Most prominent scale color in PR was yellow-white (88.3%) and in GP was white-gray (80%). In PLC varying colors were seen, most prominent being brown (53.3%). Characteristic findings seen only in PLC were hypopigmented areas (13.3%), brown dots and globules (53.3%) and orange-yellow structureless areas (61.7%) GP, PR, and PLC reveal specific dermoscopic findings that can help in differentiating them. Further, the known dermoscopic criteria for GP, PR, and PLC also apply for dark skin phototypes.

Skin manifestations of COVID-19 in children: Part 3.

The current COVID-19 pandemic is caused by the SARS-CoV-2 coronavirus. The initial recognized symptoms were respiratory, sometimes culminating in severe respiratory distress requiring ventilation, and causing death in a percentage of those infected. As time has passed, other symptoms have been recognized. The initial reports of cutaneous manifestations were from Italian dermatologists, probably because Italy was the first European country to be heavily affected by the pandemic. The overall clinical presentation, course and outcome of SARS-CoV-2 infection in children differ from those in adults as do the cutaneous manifestations of childhood. In this review, we summarize the current knowledge on the cutaneous manifestations of COVID-19 in children after thorough and critical review of articles published in the literature and from the personal experience of a large panel of paediatric dermatologists in Europe. In Part 1, we discuss one of the first and most widespread cutaneous manifestations of COVID-19, chilblain-like lesions, and in Part 2 we expanded to other manifestations, including erythema multiforme, urticaria and Kawasaki disease-like inflammatory multisystemic syndrome. In this part of the review, we discuss the histological findings of COVID-19 manifestations, and the testing and management of infected children for both COVID-19 and any other pre-existing conditions.

Symmetric blaschkoid pityriasis rosea in a child.

Pityriasis rosea (PR) is a common papulosquamous disorder that may be related to primary infection or endogenous reactivation of human herpesvirus 7 and 6. Based on morphology, distribution, and size of lesions, several atypical variants of PR have been described. PR following the lines of Blaschko represents an atypical variant that has seldom been described in the literature. Here, we describe a child with diabetes who developed PR in a symmetrical, blaschkolinear configuration.

Cutaneous manifestations of COVID-19.

The severe acute respiratory syndrome coronavirus two (SARS-CoV-2), which causes the 2019 coronavirus disease (COVID-19), has infected patients worldwide. Physicians have increasingly identified cutaneous findings as a significant clinical manifestation of COVID-19. In this review, we describe the clinical presentation, onset, duration, associated symptoms, treatment, and outcome of cutaneous manifestations thus far reported to be related to COVID-19. We have included data from 63 studies and subdivided reported cutaneous manifestations into the categories of viral exanthem, urticarial, vesicular, chilblains/chilblains-like, non-chilblains vasculopathy-related, pityriasis rosea-like, erythema multiforme-like, Kawasaki/Kawasaki-like disease, and others. Physicians should be aware of the known common cutaneous manifestations of COVID-19 and future research is required to better understand the pathophysiology and prognosis of each COVID-19-related skin manifestation.

Acute exanthemas: a prospective study of 98 adult patients with an emphasis on cytokinic and metagenomic investigation.

BACKGROUND: Acute exanthemas (AEs) are frequently seen; they can be caused by drugs or viruses but often the cause is unknown. OBJECTIVES: To describe the clinical, virological and histological aspects of AEs and explore their cytokinic and metagenomic profiles. METHODS: This prospective study examined 98 patients with AE, from February to July 2014. Clinical data were recorded in a standardized chart. Virological investigation and skin biopsies were performed. In addition, blood and skin samples were analysed for cytokines and then by a shotgun metagenomic approach. We identified five groups of patients: those with maculopapular exanthemas (MPEs) that were virally induced (group 1); those with drug-induced MPEs (group 2), those with MPEs that were both viral and drug induced (group 3), those with idiopathic MPEs (group 4) and those with pityriasis rosea (group 5). RESULTS: A virus was identified in 29 cases (human herpesvirus 6, 72%). Cytokinic analysis of the skin (n = 23 MPEs) showed higher levels of interferon-γ and interleukin-1 receptor-α in viral MPEs, higher interleukin-33 levels in idiopathic MPEs, and higher macrophage inflammatory protein 1α levels in drug-induced MPEs. By metagenomics analysis (n = 10 MPEs), viruses identified with routine practice methods were not found in group 1 (n = 4 MPEs). However, Enterovirus A was detected in two cases, especially in a group 1 patient for whom metagenomic analysis rectified the diagnosis of the culprit agent. CONCLUSIONS: Human herpesvirus 6 was the virus most frequently identified, and histology did not discriminate MPEs. In addition, the level of interleukin-33 seen in idiopathic MPEs suggests that an environmental factor may be the trigger for these. The results bring into question the utility of routine polymerase chain reaction analysis and viral serology for determining cause in AE. What's already known about this topic? Acute exanthemas, especially maculopapular exanthemas, are a frequent reason for patients consulting emergency and dermatology departments. It is difficult to evaluate the aetiology of acute exanthema based on the clinical aspects. Few data are available on the investigations needed in routine practice, and no prospective series have been published. What does this study add? Our study provides a global and prospective description of acute exanthemas. Cytokine analysis could help to investigate the pathophysiology of idiopathic eruptions. Metagenomic analysis provides new insights about the value of routine practice virological investigations. We show for the first time the feasibility of metagenomics analysis in the skin, which results question the interest of routine PCR and viral sérologies for the exploration of such acute exanthemas.

Histopathologic features distinguishing secondary syphilis from its mimickers.

BACKGROUND: Syphilis is often misdiagnosed clinically, and biopsies might be required. OBJECTIVE: To determine histopathologic features that distinguish secondary syphilis from pityriasis lichenoides (PL), pityriasis rosea (PR), and early mycosis fungoides (MF). METHODS: Histopathologic features of 100 cases of syphilis, 110 cases of PL, 72 cases of PR, and 101 cases of MF were compared. RESULTS: Elongated rete ridges and interstitial inflammation favor syphilis over PL (likelihood ratios 3.44 and 2.72, respectively), but no feature reliably distinguishes between them. Secondary syphilis and PR can be distinguished by neutrophils in the stratum corneum, plasma cells, interface dermatitis with lymphocytes and vacuoles, and lymphocytes with ample cytoplasm. Plasma cells and lymphocytes with ample cytoplasm are rare in early MF and can be used as distinguishing features. CONCLUSIONS: Histopathologic features characteristic of syphilis can be seen in PL, PR, and early MF. Distinguishing syphilis from PL can be difficult histologically, and a high index of suspicion is required. Although elongation of rete and interstitial inflammation favor syphilis, plasma cells (historically considered a significant feature of syphilis) are often encountered in PL. Vacuolar interface dermatitis with a lymphocyte in every vacuole is considered characteristic of PL, but this feature appears to be more common in syphilis.

Pityriasis rosea during omalizumab treatment for chronic spontaneous urticaria.

Pityriasis rosea (PR) is an exanthematous disease whose etiology is related to reactivation of herpes human herpesviruses 6 (HHV-6) and 7 (HHV-7). We observed two cases of PR arising during omalizumab therapy for chronic spontaneous urticaria (CSU). Here we report for the first time PR occurring during omalizumab treatment. After PR diagnosis, viral serology was performed. Data in literature about omalizumab mechanism of action, PR and HHV-6/7 infection were analyzed in order to identify possible correlations. In both our cases IgM against HHV-6 and HHV-7 were negative. The first patient presented altered IgG titers for both viruses (1:160 and 1:80, respectively) while only HHV-6 IgG (1:320) were detected in the second patient. From data in literature, we consider it presumable that apoptotic immune cells due to omalizumab immunomodulation could release viral proteins produced from integrated DNA. This could elicit cutaneous cross-reactivity and PR onset. In conclusion, we think there is a link between omalizumab therapy and PR occurring in patients with CSU. Our case history is too small to draw firm conclusions. Data collection of similar cases could be helpful to improve our knowledge.

The clinics of HHV-6 infection in COVID-19 pandemic: Pityriasis rosea and Kawasaki disease.

A new type of coronavirus family (SARS-CoV-2), which can be found in humans and animals, with many varieties and clinical symptoms, was first seen in Wuhan, China in late 2019, under the name novel Coronavirus Disease 2019 (COVID-19). In the literature, cutaneous symptoms related to the disease are generally emphasized. However, it is not yet known whether this new SARS-CoV-2 virus, which has entered our lives, plays a role in the etiopathogenesis of dermatological diseases. The patients who were admitted to the dermatology outpatient clinic between 1 April and 15 May 2019, and on 1 April and 15 May 2020 were retrospectively analyzed by searching the hospital automation system and patient files. The reason for the same months to be included in the study was to exclude seasonal effects on the diseases. After pandemic, the number of patients with Pityriasis rosea and Kawasaki disease increased significantly in patients who applied to the dermatology outpatient clinic. Our study is the first study showing Pityriasis rosea increase during the pandemic period. We think that this increase is related to HHV-6 reactivation. Herein, we wanted to draw attention to two diseases in which Human Herpes 6 (HHV-6) was accused in etiopathogenesis: Kawasaki disease and Pityriasis rosea.

HHV 6-7 reactivation causing Pityriasis Rosea and labyrinthitis: A case report.

Pityriasis Rosea (PR) and labyrinthitis are most commonly caused by viral infections. PR presents with a characteristic rash while labyrinthitis presents with vertigo, tinnitus and hearing loss. However, the coexistence of PR and Labyrinthitis remains an uncommon event. Human Herpes Virus (HHV) 6 and 7, are common infections in childhood, and their reactivation causes Pityriasis Rosea. But these viruses are not known to have any involvement with the inner ear or the 8th cranial nerve (CN).

Erythematotelangiectatic rosacea may be associated with a subclinical stage of demodicosis: a case-control study.

BACKGROUND: Facial densities of Demodex mites have been observed to be greater in patients with demodicosis and papulopustular rosacea than in healthy control patients. In patients with erythematotelangiectatic rosacea (ETR), this density has been observed to be similar to or greater than that of healthy controls. Erythema and telangiectasia, characteristics of ETR, are often observed among patients with pityriasis folliculorum, a discreet demodicosis, suggesting a possible link between these conditions. OBJECTIVES: To compare the facial Demodex densities of patients with clinical ETR and patients with healthy skin, demodicosis, rosacea with papulopustules, and other facial dermatoses. METHODS: In this retrospective study, we recorded Demodex densities measured using two consecutive standardized skin surface biopsies (SSSB1 and SSSB2) in 23 patients with ETR, 20 healthy control patients, 590 patients with demodicosis, 254 with rosacea with papulopustules and 180 with other facial dermatoses. RESULTS: Patients with ETR had higher Demodex densities (D cm-2 ) than did the healthy controls (mean ± SEM; SSSB1: 15·7 ± 6·3 vs. 1·8 ± 1·1 D cm-2 , P = 0·042; SSSB2: 38·0 ± 13·7 vs. 5·1 ± 2·1 D cm-2 , P = 0·026) and patients with other dermatoses (SSSB1: 0·4 ± 0·1 D cm-2 , P = 0·004; SSSB2: 1·3 ± 0·3 D cm-2 , P = 0·004), but lower densities than patients with demodicosis (SSSB1: 82·7 ± 4·2 D cm-2 , P = 0·008; SSSB2: 172·2 ± 7·7 D cm-2 , P = 0·001) or rosacea with papulopustules (SSSB1: 86·6 ± 7·3 D cm-2 , P = 0·027; SSSB2: 197·0 ± 12·1 D cm-2 , P = 0·002). CONCLUSIONS: ETR may be associated with nonvisible Demodex proliferation, possibly corresponding to a subclinical stage of demodicosis. Dermatologists should be aware of this potential association and look for subclinical demodicosis in patients with ETR, so that topical acaricidal treatment can be offered if Demodex density is high.