Reactivity against the BP180 ectodomain in patients with bullous pemphigoid, mucous membrane pemphigoid, multiple sclerosis and Parkinson disease.

The 16th non-collagenous domain (NC16A) of BP180 is the main antigenic target of autoantibodies in bullous pemphigoid (BP) and mucous membrane pemphigoid (MMP). Commercially available assays detect serum autoantibodies against NC16A in the majority of BP (80%-90%) and in approximately 50% of MMP patients. However, a standardized test system for detecting antibodies against other regions of BP180 is still lacking. Moreover, anti-BP180 autoantibodies have been found in neurological conditions such as multiple sclerosis and Parkinson disease. This study aimed at identifying primary epitopes recognized by BP autoantibodies on the BP180 ectodomain. Serum samples of 51 BP and 30 MMP patients both without anti-NC16A reactivity were included along with 44 multiple sclerosis and 75 Parkinson disease sera. Four overlapping His-tagged proteins covering the entire BP180 ectodomain (BP180(ec)1-4) were cloned, expressed, purified and tested for reactivity by immunoblot. IgG antibodies to BP180(ec)3 were detected in 98% of BP, 77% of MMP and 2% of normal human sera. Only weak reactivity was detected for neurological diseases against BP180(ec)1, BP180(ec)2 and BP180(ec)4, in 3%, 11% and 7% of tested multiple sclerosis sera, respectively. 8% of Parkinson disease sera reacted with BP180(ec)2 and 9% with BP180(ec)4. In conclusion, this study successfully identified epitopes recognized by BP autoantibodies outside the NC16A domain in pemphigoid diseases. These findings contribute to a better understanding of the immune response in BP and MMP with potential implications for a future diagnostic assay for NC16A-negative pemphigoid patients.

A core domain set for pyoderma gangrenosum trial outcomes: an international eDelphi and consensus study from the UPGRADE initiative.

BACKGROUND: Pyoderma gangrenosum (PG) is a rare ulcerative skin condition with no current standardized outcomes or outcome measures. With a rich investigational therapeutic pipeline, standardization of outcomes and improvement of data quality and interpretability will promote the appropriate and consistent evaluation of potential new therapies. Core outcome sets (COS) are agreed, standardized sets of outcomes that represent the minimum that should be measured and reported in all clinical trials of a specific condition. OBJECTIVES: To identify and reach a consensus on which domains (what to be measured) should be included in the Understanding Pyoderma Gangrenosum: Review and Analysis of Disease Effects (UPGRADE) core domain set for clinical trials in PG. METHODS: Collaborative discussions between patients and PG experts, and a systematic review of the literature identified items and prospective domains. A three-round international eDelphi exercise was performed to prioritize the domains and refine the provisional items (consensus: ≥ 70% of participants rating a domain as 'extremely important' and < 15% of participants voting 'not important'), followed by an international meeting to reach consensus on the core domain set (consensus: < 30% disagreement). Item-generation discussions and consensus meetings were hosted via online videoconferences. The eDelphi exercise and consensus voting were performed using Qualtrics survey software. Participants were adults with PG, healthcare professionals, researchers and industry representatives. RESULTS: Collaborative discussions and systematic reviews yielded 115 items, which were distilled into 15 prospective domains. The eDelphi exercise removed the three lowest-priority domains ('laboratory tests', 'treatment costs' and 'disease impact on family') and ranked 'pain', 'quality of life' and 'physical symptoms' as the highest-priority prospective domains. Consensus was reached on the domains of 'pain', 'quality of life' and 'clinical signs'. The domain of 'disease course/disease progression' narrowly failed to reach consensus for inclusion in the core set (32% of participants voted 'no'). Refinement of this domain definition will be required and presented for consideration at future consensus meetings. CONCLUSIONS: The UPGRADE core domain set for clinical trials in PG has been agreed by international multistakeholder consensus. Future work will develop and/or select outcome measurement instruments for these domains to establish a COS.

Mortality and Autopsy Findings in Patients with Pyoderma Gangrenosum: A Multi-Institutional Series.

INTRODUCTION: Pyoderma gangrenosum (PG) is a rare ulcerative skin condition with an increased risk of mortality compared to the general population. The causes of this increased risk are not well understood. Misdiagnosis is common in PG, and many studies are limited by the inclusion of misdiagnosed cases. The goal of this study was to review autopsy findings, identify causes of death, and identify factors that may worsen outcomes among deceased patients confirmed to have PG. METHODS: Data was retrospectively reviewed from the electronic medical records at five academic hospitals. A search was conducted for deceased patients with a diagnosis of PG who had an autopsy performed between 2010 and 2020. We report a descriptive analysis of 11 patients and their clinical characteristics, causes of death, and autopsy findings. RESULTS: The average age of death was 62.9 years. Seven patients had at least one underlying condition known to be associated with PG including inflammatory bowel disease, inflammatory arthritis, or a hematologic disorder. The most common cause of death was infection (n = 6, 54.5%), followed by pulmonary embolism (n = 3, 27.3%), and myelodysplastic syndrome (n = 2, 18.2%). Six patients (54.5%) were taking systemic steroids at the time of death. CONCLUSION: The development of PG may shorten life expectancy among those with underlying conditions associated with PG, and common treatments for PG may contribute to the risk of fatal complications. Awareness of the risk of infection, thrombosis, and malignancy among those with PG is necessary for proper management. Further research is needed to explore the relationship between PG and thromboembolism.

Paediatric cutaneous lymphomas including rare subtypes: A 40-year experience at a tertiary referral centre.

BACKGROUND: Primary cutaneous lymphomas are neoplasms of the immune system with a distinct tropism for the skin and an absence of extracutaneous manifestations at the time of diagnosis. Studies focusing on cutaneous lymphomas in children and adolescents remain scarce and often do not encompass the rare subtypes. OBJECTIVES: To address this knowledge gap by describing the clinical, histological and molecular characteristics of a large group of paediatric patients affected by primary cutaneous lymphoma. We also provided the Paediatric Primary Cutaneous Lymphoma Atlas that illustrates the clinicopathological spectrum of observed presentations, in the hope of supporting other physicians in the diagnostic process. METHODS: Retrospective chart review of paediatric patients diagnosed with primary cutaneous lymphomas between 1980 and 2022 at the Paediatric Dermatology Unit of Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan. RESULTS: A total of 101 patients (58 males, 43 females) met the inclusion criteria. The most common subtypes were lymphomatoid papulosis (n = 48) and mycosis fungoides (n = 31). These were followed by primary cutaneous CD4+ small/medium T-cell lymphoproliferative disorders (n = 7), primary cutaneous anaplastic large-cell lymphomas (n = 5), primary cutaneous marginal zone B-cell lymphomas (n = 3), primary cutaneous follicle centre lymphomas (n = 2), subcutaneous panniculitis-like T-cell lymphomas (n = 2), primary cutaneous peripheral T-cell lymphoma not otherwise specified (n = 1), primary cutaneous precursor B-lymphoblastic lymphoma (n = 1) and Sézary syndrome (n = 1). Clinical follow-up data covering a median of 70.8 months (range 1-324) were available for 74 patients, of whom three died due to cutaneous lymphoma. CONCLUSIONS: Our findings shed light on the peculiar aspects and long-term outcomes of paediatric cutaneous lymphomas, particularly emphasizing their distinctive features in comparison to their adult counterparts and exploring the less common subtypes. Further larger-scale studies are warranted to better characterize these entities and to achieve a more rapid and accurate diagnosis.

Discrepancies in hidradenitis suppurativa lesion characterization by providers and patients.

BACKGROUND: The hidradenitis suppurativa (HS) clinical response (HiSCR) has come under scrutiny as several HS clinical trials failed to meet primary endpoints with high placebo responses. This may be due to limitations of the tool and raters' ability to accurately characterize and count lesions, rather than lack of efficacy of the studied drug. Due to HS lesion complexity and potential differences in rater training, it was hypothesized that there would be discrepancies in how providers characterize and count lesions for HS clinical trials. OBJECTIVE: To evaluate how HS providers and patients name and count HS lesions and to identify discrepancies among providers to initiate the development of consensus-driven guidance for HS rater training. METHODS: An online survey was distributed to the members of HIdradenitis SuppuraTiva cORe outcomes set International Collaboration (HISTORIC). Respondents were asked to classify lesion images composed of multiple and different morphology types and answer questions regarding inclusion of associated dermatological conditions. RESULTS: Forty-seven HISTORIC members responded (29 providers; 18 patients). There was variability in how respondents classified HS lesions. Of 12 questions containing images, four had ≥50% of respondents choosing the same answer. With an image of a lesion composed of different morphologies, 45% of providers counted it as a single lesion and 45% counted it as multiple distinct lesions. With an image of multiple interconnected draining tunnels, 7% of providers classified it as a single draining tunnel while 79% categorized it as multiple draining tunnels with the number estimated by visual inspection. There was also variability in deciding whether lesions occurring in associated conditions should be considered separately or included in HS lesion counts. Patient responses were also variable. CONCLUSIONS: The result of the current study reaffirms the gap in how providers characterize and count HS lesions for clinical trials and the need to develop consensus-driven rater training related to HS outcome measures.

Association between maternal dupilumab exposure and pregnancy outcomes in patients with moderate-to-severe atopic dermatitis: A nationwide retrospective cohort study.

BACKGROUND: There is limited epidemiological evidence on outcomes associated with dupilumab exposure during pregnancy; monitoring pregnancy outcomes in large populations is required. OBJECTIVE: To investigate the potential association between exposure to dupilumab in pregnant women with atopic dermatitis and any adverse pregnancy, neonatal, congenital and post-partum outcomes. METHODS: We performed a multicentre retrospective cohort study across 19 Italian tertiary referral hospital. Childbearing women were eligible if aged 18-49 years and carried out the pregnancy between 1 October 2018 and 1 September 2022. RESULTS: We retrospectively screened records of 5062 patients receiving dupilumab regardless of age and gender, identifying 951 female atopic dermatitis patients of childbearing age, 29 of whom had been exposed to the drug during pregnancy (3%). The median duration of dupilumab treatment prior to conception was 22.5 weeks (range: 3-118). The median time of exposure to the drug during pregnancy was 6 weeks (range: 2-24). All the documented pregnancies were unplanned, and the drug was discontinued in all cases once pregnancy status was reported. The comparison of the study cohort and the control group found no significant drug-associated risk for adverse pregnancy, congenital, neonatal or post-partum outcomes. The absence of a statistically significant effect of exposure on the event was confirmed by bivariate analysis and multivariate analysis adjusted for other confounding factors. CONCLUSIONS: This cohort of pregnant patients exposed to dupilumab adds to the existing evidence concerning the safety of biologic agents in pregnancy. No safety issues were identified regarding the primary outcome assessed. In clinical practice, these data provide reassurance in case of dupilumab exposure during the first trimester. However, the continuous use of dupilumab throughout pregnancy warrants further research.

Characterisation of IL-1 family members in Sweet syndrome highlights the overexpression of IL-1ß and IL-1R3 as possible therapeutic targets.

Sweet syndrome (SS) as a prototypic neutrophilic dermatosis (NDs) shares certain clinical and histologic features with monogenic auto-inflammatory disorders in which interleukin (IL)-1 cytokine family members play an important role. This has led to the proposal that NDs are polygenic auto-inflammatory diseases and has fuelled research to further understand the role of IL-1 family members in the pathogenesis of NDs. The aim of this study was to characterise the expression of the IL-1 family members IL-1ß, IL-36γ, IL-33 and IL-1R3 (IL-1RaP) in SS. The expression profile of IL-1ß, IL-33, IL-36γ and their common co-receptor IL-1R3 was analysed by immunohistochemistry, in situ hybridisation and double immunofluorescence (IF) in healthy control skin (HC) and lesional skin samples of SS. Marked overexpression of IL-1ß in the dermis of SS (p < 0.001), and a non-significant increase in dermal (p = 0.087) and epidermal (p = 0.345) IL-36γ expression compared to HC was observed. Significantly increased IL-1R3 expression within the dermal infiltrate of SS skin samples (p = 0.02) was also observed, whereas no difference in IL-33 expression was found between SS and HC (p = 0.7139). In situ hybridisation revealed a good correlation between gene expression levels and the above protein expression levels. Double IF identifies neutrophils and macrophages as the predominant sources of IL-1ß. This study shows that IL-1ß produced by macrophages and neutrophils and IL-1R3 are significantly overexpressed in SS, thereby indicating a potential pathogenic role for this cytokine and receptor in SS.

SARS-CoV-2 Detection by Digital Polymerase Chain Reaction and Immunohistochemistry in Skin Biopsies from 52 Patients with Different COVID-19-Associated Cutaneous Phenotypes.

BACKGROUND: COronaVIrus Disease 19 (COVID-19) is associated with a wide spectrum of skin manifestations, but SARS-CoV-2 RNA in lesional skin has been demonstrated only in few cases. OBJECTIVE: The objective of this study was to demonstrate SARS-CoV-2 presence in skin samples from patients with different COVID-19-related cutaneous phenotypes. METHODS: Demographic and clinical data from 52 patients with COVID-19-associated cutaneous manifestations were collected. Immunohistochemistry and digital PCR (dPCR) were performed in all skin samples. RNA in situ hybridization (ISH) was used to confirm the presence of SARS-CoV-2 RNA. RESULTS: Twenty out of 52 (38%) patients presented SARS-CoV-2 positivity in the skin. Among these, 10/52 (19%) patients tested positive for spike protein on immunohistochemistry, five of whom had also positive testing on dPCR. Of the latter, one tested positive both for ISH and ACE-2 on immunohistochemistry while another one tested positive for nucleocapsid protein. Twelve patients showed positivity only for nucleocapsid protein on immunohistochemistry. CONCLUSIONS: SARS-CoV-2 was detected only in 38% of patients, without any association with a specific cutaneous phenotype, suggesting that the pathophysiology of cutaneous lesions mostly depends on the activation of the immune system. The combination of spike and nucleocapsid immunohistochemistry has higher diagnostic yield than dPCR. Skin persistence of SARS-CoV-2 may depend on timing of skin lesions, viral load, and immune response.

External Validation of the IHS4-55 in a European Antibiotic-Treated Hidradenitis Suppurativa Cohort.

BACKGROUND: Previously, a new dichotomous outcome was developed, calculated as 55% reduction in the International Hidradenitis Suppurativa 4 (IHS4-55) score. It was validated in datasets of adalimumab and placebo-treated HS patients. External validation is an important aspect of clinical outcomes. OBJECTIVES: We aimed to externally validate the novel dichotomous IHS4-55 in a non-biologic treated dataset of HS patients. METHODS: Data from a previously published European-wide prospective clinical study of antibiotic treatment of HS patients were used to assess the association of IHS4-55 achievement with individual reduction in inflammatory nodules, abscesses, and draining tunnels. Moreover, the associations between IHS4-55 positivity and achievement of the minimal clinically important differences (MCIDs) for Dermatology Life Quality Index (DLQI), Numerical Rating Scale (NRS) Pain, and NRS Pruritus were analyzed. RESULTS: Data were obtained from 283 individual patients, of which 36.4% (103/283) were treated with clindamycin and rifampicin and 63.6% (180/283) with tetracyclines for 12 weeks. Achievers of the IHS4-55 demonstrated a significant reduction the counts of inflammatory nodules, abscesses, and draining tunnels (all p < 0.001). Additionally, IHS4-55 achievers had an odds ratio for achieving the MCID of DLQI, NRS Pain, and NRS Pruritus of 2.16 (95% CI 1.28-3.65, p < 0.01), 1.79 (95% CI 1.10-2.91, p < 0.05), and 1.95 (95% CI 1.18-3.22, p < 0.01), respectively. CONCLUSIONS: This study shows the external validity of the novel IHS4-55 by demonstrating a significant association between IHS4-55 achievement and a reduction in inflammatory lesion counts as well as achievement of MCIDs for DLQI, NRS Pain, and NRS Pruritus in an antibiotic-treated cohort. These findings support the use of the IHS4-55 as a novel primary outcome measure in clinical trials.

Anti-COVID-19 measurements for hidradenitis suppurativa patients.

The reported incidence of COVID-19 among cohorts of patients with inflammatory bowel and skin diseases under treatment with biologicals is low. Treatment may further modify disease severity as some biological modifiers, such as anakinra, are also proposed for the management of COVID-19 patients potentially providing HS patients with an advantage. The above preliminary evidence suggests that hidradenitis suppurativa (HS) does probably not provide an increased susceptibility for COVID-19 and that any susceptibility is unlikely to be modified negatively by treatment with biologicals. On the occasion of its 10th International Conference, experts of the European Hidradenitis Suppurativa Foundation e.V. have prepared a consensus statement regarding anti-COVID-19 measurements for HS patients. Based on the available knowledge, patients with HS may be vaccinated against SARS-CoV2 and patients affected by metabolic syndrome constitute a high-risk group for COVID-19 and should be vaccinated at the earliest convenient point in time. HS patients on treatment with adalimumab can be vaccinated with non-living virus anti-SARS-CoV2 vaccines. A possible suboptimal effect of the vaccine may be suspected but might not be expected universally. The management of the biological treatment in HS patients is at the discretion of the dermatologist / responsible physician.

Target molecules for future hidradenitis suppurativa treatment.

The registration of the tumour necrosis factor-α inhibitor adalimumab in 2015 was a major step forward in the treatment of hidradenitis suppurativa/acne inversa (HS). However, it soon became evident that the effectiveness of adalimumab in daily practice was highly variable. A significant unmet medical need of HS patients remained, and the search for novel therapeutic targets was intensified. During the 10th European Hidradenitis Suppurativa Foundation (EHSF) e.V. Conference, reknown international HS investigators virtually presented and discussed the published data on these potential target molecules for future HS treatment. This article addresses the most promising molecules currently under investigation from a pathophysiological and clinical point of view. With phase III trials ongoing, the anti- interleukin (IL)-17 biologics bimekizumab and secukinumab are in the most advanced stage of clinical development showing promising results. In addition, targeting IL-1α with bermekimab has shown encouraging results in two clinical trials. Directing treatment at neutrophil recruitment and activation by targeting IL-36 with spesolimab fits well in the pathogenic concept of HS and clinical phase II trial results are pending. In contrast to in situ evidence, Complement 5a (C5a) and C5a receptor blockade have only shown greater clinical benefit in patients with severe HS. Inhibition of Janus kinase (JAK) 1 signalling in HS showed clinical efficacy only in the highest dosage, highlighting that careful surveillance of the balance between safety and efficacy of JAK inhibition is warranted. Overall, clinical efficacies of all novel treatments reported so far are modest. To guide drug development, more and better-defined translational data on the pathogenesis of this severe and enigmatic inflammatory skin disease are required.

The efficacy and tolerability of tetracyclines and clindamycin plus rifampicin for the treatment of hidradenitis suppurativa: Results of a prospective European cohort study.

BACKGROUND: Tetracyclines and clindamycin plus rifampicin combination therapy are both considered first-line therapy in current hidradenitis suppurativa guidelines. However, evidence for their efficacy is drawn from small studies, often without validated outcomes. OBJECTIVE: To assess the 12-week efficacy of oral tetracyclines and a combination of clindamycin and rifampicin. METHODS: A prospective, international cohort study performed between October 2018 and August 2019. RESULTS: In total, 63.6% of the included 283 patients received oral tetracyclines, and 36.4% were treated with clindamycin and rifampicin. Both groups showed a significant decrease in International Hidradenitis Suppurativa Severity Score System from baseline (both P < .001). The Hidradenitis Suppurativa Clinical Response (HiSCR) was achieved in 40.1% and 48.2% of patients, respectively (P = .26). Patient characteristics or disease severity were not associated with the attainment of HiSCR or the minimal clinically important differences for the Dermatology Life Quality Index and pain. LIMITATIONS: Cohort study. Respectively, 23.9% and 19.4% of patients had to be excluded from the HiSCR analysis for the tetracycline and combination therapy group because of a low abscess and nodule count at baseline. CONCLUSION: This study shows significant efficacy of both tetracycline treatment and clindamycin and rifampicin combination therapy after 12 weeks in patients with hidradenitis suppurativa. No significant differences in efficacy were observed between the 2 treatments, regardless of disease severity.

Vascularization and fibrosis are important ultrasonographic tools for assessing response to adalimumab in hidradenitis suppurativa: Prospective study of 32 patients.

Hidradenitis suppurativa (HS) is a debilitating skin disease presenting with nodules, abscesses, and fistulae preferentially in the main folds. Adalimumab is the only licensed biologic for moderate-to-severe HS. Ultrasound demonstrated good sensitivity to provide anatomic and functional information in HS; in particular assessing vascularization, related to inflammation, and fibrosis in HS lesions before and after adalimumab treatment with ultrasound and Color Doppler may integrate clinical evaluation with imaging. Patients with moderate-to-severe HS were enrolled in this observational prospective study. Clinical evaluation (according to Hurley classification and International Hidradenitis Suppurativa Severity Score System score) and ultrasound (according to US HS-PGA)/Color Doppler were performed at baseline and after 12 weeks of adalimumab. Ultrasound was used for assessing fibrosis and Color Doppler for vascularization. For each patient, the three most severe lesions among abscesses and fistulae were chosen for total 96 lesions. Thirty-two patients were included, 18 men (56%) and 14 women (44%) with mean age 41.2. Mean IHS4 was 22.4 at baseline and dropped to 14.7 at week 12. Based on US HS-PGA, 14 out of 32 patients fell down by one or more classes of severity. Interestingly, adalimumab led to overall decrease in vascularization, particularly in lesions with intense vascular flow, which were 78 (81.3%) at baseline and became only 25 (26.04%). Finally, marked increase in fibrosis was seen after adalimumab, notably in lesions without fibrosis, which were 81 (84.4%) at baseline and became 15 (15.6%). This study confirms the efficacy of adalimumab in HS and provides value for vascularization and fibrosis as important ultrasonographic tools integrating clinical scores.

What causes hidradenitis suppurativa ?-15 years after.

The 14 authors of the first review article on hidradenitis suppurativa (HS) pathogenesis published 2008 in EXPERIMENTAL DERMATOLOGY cumulating from the 1st International Hidradenitis Suppurativa Research Symposium held March 30-April 2, 2006 in Dessau, Germany with 33 participants were prophetic when they wrote "Hopefully, this heralds a welcome new tradition: to get to the molecular heart of HS pathogenesis, which can only be achieved by a renaissance of solid basic HS research, as the key to developing more effective HS therapy." (Kurzen et al. What causes hidradenitis suppurativa? Exp Dermatol 2008;17:455). Fifteen years later, there is no doubt that the desired renaissance of solid basic HS research is progressing with rapid steps and that HS has developed deep roots among inflammatory diseases in Dermatology and beyond, recognized as "the only inflammatory skin disease than can be healed". This anniversary article of 43 research-performing authors from all around the globe in the official journal of the European Hidradenitis Suppurativa Foundation e.V. (EHSF e.V.) and the Hidradenitis Suppurativa Foundation, Inc (HSF USA) summarizes the evidence of the intense HS clinical and experimental research during the last 15 years in all aspects of the disease and provides information of the developments to come in the near future.

Autoantibody Profile of a Cohort of 54 Italian Patients with Linear IgA Bullous Dermatosis: LAD-1 Denoted as a Major Auto-antigen of the Lamina Lucida Subtype.

Linear IgA bullous dermatosis (LABD) is characterized by presence of multiple IgA autoantibodies, and a comparatively lesser number of IgG antibodies, directed against different hemidesmosomal antigens. The main autoantigens are LAD-1, LABD-97, BP180 and BP230, type VII collagen and laminin 332. We retrospectively studied the serology of 54 Italian patients with LABD using enzyme-linked immunosorbent assay (ELISA), immunoblotting assay, and indirect immunofluorescence on monkey oesophagus and salt-split skin. Among these, indirect immunofluorescence of salt-split skin elicits the greatest sensitivity. Sixty-three percent of the sera were observed to be positive, with a lamina lucida pattern observed in 48%, a sub-lamina densa pattern in 2% and a mixed pattern in 13% of the cases. IgA reactivity to LAD-1 on immunoblotting was found in 52% of sera, to BP180-NC16A by ELISA in 32% and to BP230 in 26%. Only 17% of patients possessed circulating IgG autoantibodies. LAD-1 was determined to be a major autoantigen of the lamina lucida subtype. Combined serological assays demonstrated a high sensitivity (82%), suggesting that this approach could support diagnosis when a biopsy is not feasible or direct immunofluorescence results are negative.

Varicella-like exanthem associated with COVID-19 in an 8-year-old girl: A diagnostic clue?

It has been reported that the novel coronavirus disease (COVID-19) may be associated with a papulovesicular skin eruption predominantly involving the trunk. We hereby present a case of COVID-19-associated varicella-like exanthem in an 8-year-old girl with mild systemic symptoms.

Coexistence of steatocystoma multiplex and hidradenitis suppurativa: Assessment of this unique association by means of ultrasonography and Color Doppler.

BACKGROUND: Steatocystoma multiplex (SM) is an uncommon skin disease manifesting as multiple sebum-containing cysts arising in pilosebaceous unit-rich body areas. Hidradenitis suppurativa (HS) is a debilitating chronic inflammatory disease affecting the apocrine gland-bearing skin and presenting with both pseudocystic and inflammatory nodules, abscesses and fistulas. Considering that genetics has been reported to play a role in both entities, the albeit rare association between them suggests a shared genetic background. Although histology remains the gold standard for the diagnosis of SM, ultrasonography can be an useful diagnostic tool. This method is largely used in combination with Color Doppler for assessing disease severity in HS. MATERIALS AND METHODS: We report three cases of coexisting SM and HS and describe the ultrasonography and Color Doppler features of the two entities. RESULTS: SM lesions appeared on ultrasonography as hypoechoic nodules with well-defined hyperechoic borders and posterior acoustic enhancement, in the absence of Color Doppler signal. HS lesions had the ultrasonographic features of the fistulas, abscesses and pseudocystic nodules, some of which including hair fragments, with an intense Color Doppler signal within or around inflamed lesions. CONCLUSION: The combination of ultrasonography and Color Doppler proved to be a reliable instrument for differentiating between SM and HS lesions, particularly distinguishing HS pseudocystic nodules from true cysts of SM.