Cutaneous manifestations in patients with COVID-19: a preliminary review of an emerging issue.

BACKGROUND: The infection caused by the recently identified SARS-CoV-2, called coronavirus disease-19 (COVID-19), has rapidly spread throughout the world. With the exponential increase of patients worldwide, the clinical spectrum of COVID-19 is being better defined and new symptoms are emerging. Numerous reports are documenting the occurrence of different cutaneous manifestations in patients with COVID-19. OBJECTIVES: To provide a brief overview of cutaneous lesions associated with COVID-19. METHODS: A literature search was performed in the PubMed, Scopus and Web of Science databases up to 30 April 2020. This narrative review summarizes the available data regarding the clinical and histological features of COVID-19-associated skin manifestations. RESULTS: The literature reports showed a great heterogeneity in COVID-19-associated cutaneous manifestations, as well as in their latency periods and associated extracutaneous symptoms. Pathogenic mechanisms are unknown, although the roles of a hyperactive immune response, complement activation and microvascular injury have been hypothesized. Based on our experience and the literature data, we subdivided the reported cutaneous lesions into six main clinical patterns: (i) urticarial rash; (ii) confluent erythematous-maculopapular-morbilliform rash; (iii) papulovesicular exanthem; (iv) chilblain-like acral pattern; (v) livedo reticularis-livedo racemosa-like pattern; and (vi) purpuric 'vasculitic' pattern. These six patterns can be merged into two main groups: the first - inflammatory and exanthematous - includes the first three groups listed above, and the second includes the vasculopathic and vasculitic lesions of the last three groups. CONCLUSIONS: The possible presence of cutaneous findings leading to suspect COVID-19 puts dermatologists in a relevant position. Further studies are needed to delineate the diagnostic and prognostic values of such cutaneous manifestations.

The link between chronic spontaneous urticaria and metabolic syndrome.

SUMMARY: Metabolic syndrome (MS) is a cluster of risk factors for cardiovascular disease and is considered a chronic low-level systemic inflammatory condition. Recent preliminary findings have shown an increased prevalence of MS among patients with chronic urticaria (CU) as compared to controls, with a particularly higher prevalence detected in patients with uncontrolled CU. Chronic spontaneous urticaria (CSU) appears to share some pathomechanisms with MS, including a pro-inflammatory state, increased oxidative stress, alterations in adipokine profile and activation of the coagulation system. Further studies are needed to assess the association of MS and its components with CU/CSU and to obtain more precise information regarding epidemiological aspects, clinical significance and implications. The aim of this review is to present the most relevant literature data on the link between CU/CSU and MS.

Epidemiology of chronic spontaneous urticaria: results from a nationwide, population-based study in Italy.

BACKGROUND: Chronic spontaneous urticaria (CSU) is a common skin disease, but there is a paucity of precise epidemiological data on this disease. OBJECTIVES: To obtain information on the epidemiology of CSU in Italy. METHODS: The data source was the Health Search IMS Health Longitudinal Patient Database. The study population was formed by patients aged ≥ 15 years, registered with a total of 700 general practitioners, homogeneously distributed across Italy. An algorithm based on the International Classification of Diseases, ninth revision, Clinical Modification was used for the identification of patients with CSU. The annual prevalence and incidence rates of CSU over a 12-year period (2002-2013) were estimated, along with demographic and clinical determinants. RESULTS: The annual prevalence of CSU ranged from 0·02% in 2002 to 0·38% in 2013. The incidence was 0·10-1·50 per 1000 person-years. For both prevalence and incidence rates, female patients outnumbered male. The risk of CSU was statistically significantly higher in the presence of the following variables: obesity; anxiety, dissociative and somatoform disorders; malignancies; use of immunosuppressive drugs; and chronic use of systemic corticosteroids. History of autoimmune thyroiditis showed a trend towards an increased risk of CSU, though it was not statistically significant. Smoking was associated with a significantly reduced risk of CSU. CONCLUSIONS: Our findings on CSU prevalence are consistent with those obtained in previous studies. Furthermore, this large population-based study provides important information regarding the association of CSU with demographic and clinical determinants, which have been examined in the primary-care setting.

Hair disorders associated with autoimmune connective tissue diseases.

Hair disorders are frequently observed in various systemic diseases, including autoimmune connective tissue diseases (CTDs), with predilection of lupus erythematosus (LE), followed by dermatomyositis (DM) and scleroderma. Hair disorders in CTDs may manifest as various clinical patterns, such as telogen hair loss, diffuse thinning or fragility of hair, and scarring alopecia. Less common hair disorders include anagen effluvium, alopecia areata, and trichomegaly. Some drugs used to treat CTDs may cause hair loss in a drug-related manner or hyperthrichosis. In the assessment of common hair loss patterns, such as telogen effluvium, the possible association with CTDs must be borne in mind and should not be overlooked. Alopecia appears to be a significant sign in the course of LE and especially systemic LE. In DM, the involvement of the scalp is common, and is often characterized by a diffuse, violaceous, scaly, non-scarring and symptomatic hair loss. Linear scleroderma en coup de sabre is an uncommon localized form of morphea with involvement of the paramedian forehead and frontal scalp, where it is associated with cicatricial alopecia. The most important variant of scarring alopecia in the context of CTDs is that associated with discoid lupus erythematosus (DLE). In the diagnostic work-up of DLE-related cicatrical alopecia, histopathological and immunopathological studies are useful, and a relevant role has been attributed to dermatoscopy (trichoscopy) over the last years. Hair loss has been reported in several other CTDs, including mixed and undifferentiated CTDs, and primary Sjögren's syndrome, although it is likely to be underestimated in such diseases.

Survival rate of antitumour necrosis factor-α treatments for psoriasis in routine dermatological practice: a multicentre observational study.

BACKGROUND: Adherence is an overall marker of treatment success, and it depends on multiple factors including efficacy and safety. Despite the wide use of tumour necrosis factor (TNF)-α blockers in the treatment of plaque-type psoriasis, few data regarding treatment adherence in routine clinical practice are available. OBJECTIVES: To estimate the long-term survival rate of anti-TNF-α therapy in a cohort of patients with psoriasis in routine clinical practice; to evaluate the reasons for and predictors of treatment discontinuation. METHODS: The Outcome and Survival rate Concerning Anti-TNF Routine treatment (OSCAR) study was based on a retrospective analysis to estimate the long-term survival rate of the first anti-TNF-α treatment in patients with psoriasis, from three Italian academic referral centres. Adult patients (n = 650) with plaque psoriasis treated with a first course of adalimumab, etanercept or infliximab for ≥ 3 months were included. RESULTS: Global adherence to anti-TNF-α treatments after 28·9 ± 15·4 months (867 ± 462 days) of observation was 72·6%. Etanercept showed a longer survival (mean 51·4 months, 1565 days; P < 0·001) compared with infliximab (36·8 months, 1120 days) and adalimumab (34·7 months, 1056 days). Treatment discontinuation due to primary and secondary inefficacy was observed in 5·2% and 14·5% of patients, respectively, whereas discontinuation due to adverse events was reported in 29 subjects (4·5%). Independent predictors of treatment withdrawal were female gender [hazards ratio (HR) 1·3], treatment with adalimumab or infliximab compared with etanercept (HR 2·7 and 1·7, respectively), and the concomitant use of traditional systemic treatment, as a rescue therapy, compared with monotherapy (HR 1·9). CONCLUSIONS: Overall survival of anti-TNF-α agents in psoriasis is elevated, with drug discontinuation mostly due to inefficacy. Etanercept showed a longer adherence compared with adalimumab and infliximab.

Cyclosporine regimens in plaque psoriasis: an overview with special emphasis on dose, duration, and old and new treatment approaches.

Cyclosporine A (CsA) is one of the most effective systemic drugs available for the treatment of psoriasis, as evidenced by the results of several randomized studies and by a prolonged experience in dermatological setting. In clinical practice, CsA is usually used for the induction of psoriasis remission at a daily dose included in the range of 2.5-5 mg/kg and with intermittent short-term regimens, lasting on average 3-6 months. The magnitude and rapidity of response are dose dependent, as well as the risk of development of adverse events. Therefore, the dose should be tailored to patient's needs and general characteristics and adjusted during the treatment course according to both the efficacy and tolerability. Some studies support the feasibility of pulse administration of CsA for a few days per week for both the induction and the maintenance of response in psoriasis patients. This paper will review the data on CsA regimens for plaque-type psoriasis and will focus the attention on dose, treatment duration, novel schedules, and role in combination therapies, including the association with biologicals.

Janus kinase inhibition as a potential strategy for the treatment of psoriasis: state of the art and future perspectives.

Research is focusing the attention on drugs acting on intracellular signaling as a possible strategy for various malignancies and autoimmune disorders, as well as prevention of transplant rejection. In such a context, an intriguing therapeutic target appears to be the signaling pathway mediated by Janus kinases (JAK)/signal transducers and activators of transcription (STAT) protein family. Several companies are developing and evaluating JAK inhibitors for immune-mediated disorders, including psoriasis. Among these drugs, ruxolitinib and especially tofacitinib have reached more advanced phases of clinical and experimental development. This review discusses the potential role of JAK inhibition in the treatment of psoriasis and presents the preliminary data regarding the clinical development of JAK inhibitors in this disease.

Psodisk, a new visual method for assessing the burden of psoriasis on patients.

BACKGROUND: The last decades have witnessed an increasing interest for the psychosocial aspects of chronic skin diseases, such as psoriasis. Nonetheless, systematic assessments of the impact of psoriasis on patients' lives are rarely done in daily clinical practice. The existing instruments are mostly meant to be completed by patients alone, and rarely comprise a graphical representation of the results. OBJECTIVE: To develop a questionnaire allowing both a quick assessment of the impact of psoriasis on patients and, at the same time, an intuitive graphic visualization of the outcome of the test. METHODS: A preliminary version of an Italian questionnaire aimed to assess the global impact of psoriasis on patients, meant to be filled in together by the patient and the dermatologist and to produce visual, intuitive results, was developed through focus groups. The instrument was then the object of a Delphi survey addressed to a panel of experts, to assess both the need of possible improvements of the questionnaire (in terms of the formulations of the questions and of the domains to be explored) and the usefulness of the questionnaire. RESULTS: A 10-item questionnaire in Italian, taking into account different aspects of the burden of psoriasis on the patient, was developed. The answers are given on a 10-point visual analogue scale and graphically represented on a disc as a polygon. CONCLUSIONS: A formal validation of the questionnaire and a study to assess potential clinical and psychological benefits of a systematic implementation of the instrument in daily practice are planned.

Methyl-aminolevulinate photodynamic therapy for the treatment of actinic cheilitis: a retrospective evaluation of 29 patients.

AIM: Multiple treatment modalities have been proposed for actinic cheilitis (AC), and topical photodynamic therapy (PDT) has recently been included among these modalities. We report our experience with PDT using methyl-aminolevulinate (MAL) in AC. METHODS: We performed a retrospective analysis of 29 patients who had undergone MAL-PDT for treatment of AC: 4 patients received one single session and 25 patients two consecutive weekly sessions. RESULTS: At 3 months, 21 patients (72%) obtained a complete clinical response, which was sustained over a follow-up period of 6-36 months (mean, 20 months) in 20 patients. Cosmetic outcome was generally rated as good or very good. Transient local adverse events related to the procedure were common and mild to moderate in the majority of cases. CONCLUSION: Our preliminary experience suggests that MAL-PDT may be considered a valid modality for the treatment of AC, although long-term follow-up studies in large patient series are required to obtain precise data about clinical and histological recurrences.

Anti-tumor necrosis factor treatment in occult hepatitis B virus infection: a retrospective analysis of 62 patients with psoriatic disease.

One of the problems possibly related to the use of biological agents targeting tumor necrosis factor (TNF)-alpha is the increased risk of infections, including the activation of hepatitis B virus (HBV). HBV activation can occur in carriers of hepatitis B surface antigen (HBsAg), but the risk may also involve the HBsAg-negative (anti-HBc ± anti-HBs) occult carriers. Precise data on the safety of anti-TNF and/or other immunosuppressive drugs in HBV occult carriers are not available. We performed a retrospective analysis of 62 psoriatic patients with occult HBV infection treated with anti-TNF biological agents over a period of approximately 4 years: 44 subjects were treated with etanercept, 8 with infliximab and 10 with adalimumab. During the observational treatment period, no signs of HBV activation were observed. Only in one patient the reappearance of HBsAg, without detectable HBV-DNA, was noted before retreatment with etanercept and after 10 months from discontinuation of the previous course. In this patient etanercept was re-administered in association with lamivudine without any adverse event. Our results suggest the overall safety of treatment with anti-TNF drugs in HBV occult carriers, although a careful and constant monitoring of virological markers is required in such patients during treatment with anti-TNF drugs in order to have an early recognition of viral reactivation.

Molecular characterization of novel melanoma cell lines.

We isolated two novel cell lines from different types of sporadic human malignant melanoma: the hmel1 line was obtained from a melanoma skin metastasis and the hmel9 cell line from a primary superficial spreading melanoma. The karyotype and pigmentation parameters were assessed in these cell lines. Cytogenetic analysis in early stages of culture revealed that both cell lines had chromosome instability and simultaneous growth of heteroploid subpopulations. The molecular analysis of some genes involved in melanoma showed that both cell lines harbor BRAF mutations. The unpigmented hmel1 and the pigmented hmel9 lines were found to express the tyrosinase gene. The tyrosine hydroxylase activity was detectable only in hmel9 cells and practically absent in the hmel1 cell line. This activity was found to be correlated with the relative tyrosinase protein amount in both melanoma cell lines. The biological behaviour in the two melanoma cell lines, derived from two different types of melanoma lesions displaying distinct clinical and histopathological features, confirms the heterogeneous characteristics of sporadic melanoma. Similarities and/or differences between cell lines extracted from different melanoma cases could be useful in the future for diagnostic, prognostic and therapeutic purposes.

Oral supplementation with a nutraceutical containing Echinacea, methionine and antioxidant/immunostimulating compounds in patients with cutaneous viral warts.

AIM: The aim of thos paper was to determine the effect of oral supplementation (OS) with a nutraceutical, containing methionine, Echinacea, zinc, probiotics and other antioxidant and immunostimulating compounds, on the response of cutaneous warts to conventional standard therapy (CST). METHODS: This was an open-label study in adults and adolescents aged 14 years or more and with a body weight ≥40 kg, who had at least one cutaneous viral wart. Eligible patients were consecutively allocated to CST (topical therapy with a preparation containing salicylic acid and lactic acid or liquid nitrogen cryotherapy) alone or CST combined with nutraceutical OS for 4 months. RESULTS: A total of 172 patients were enrolled: 83 received CST alone and 89 CST+OS. During the 6-month observation period, a statistically significant reduction of the mean number of warts was obtained in each treatment group and subgroup. The addition of nutraceutical OS was associated with a significantly lower number of warts at 6 months as compared to CST alone. Complete remission was obtained in 54.5% and 86% of patients in the CST group and CST+OS arm, respectively (P<0.001). The influence of the nutraceutical on the response rate appeared to be more prominent in the subgroup of patients treated with topical therapy. The development of new warts during the study period occurred significantly less frequently with CST+OS compared to CST (9% versus 25%; P=0.004). No adverse events possibly related to the nutraceutical administration were observed. CONCLUSION: Our pilot experience seems to suggest that nutraceutical OS is safe and beneficial in patients with cutaneous warts, and capable of enhancing the response to CST.

Psoriasis relapse evaluation with week-end cyclosporine A treatment: results of a randomized, double-blind, multicenter study.

Cyclosporine A (CsA) effectively controls psoriasis, however, its long-term continuous use is not recommended. This study aims to evaluate the efficacy and tolerability of week-end CsA microemulsion for the reduction of relapse rate in patients with chronic plaque psoriasis who had achieved clinical remission following continuous CsA therapy. The PREWENT (Psoriasis Relapse Evaluation with Week-End Neoral Treatment) study was a 24 week, randomized, double-blind, multicenter study, carried out in 22 Italian hospital or University Dermatology units. CsA was discontinued for 8 days previous to the patients being randomized to oral CsA 5 mg/kg/day or placebo for two consecutive days/week, for a total period of 24 weeks. The primary endpoint was clinical success rate at week 24, defined as the proportion of patients with no clinical worsening (no relapse or a Psoriasis Area and Severity Index (PASI) < 75 percent of pre-treatment PASI). A total of 162 patients were randomized to CsA and 81 to placebo. Clinical success rates at 24 weeks were 66.9 and 53.2 percent with CsA and placebo, respectively (p = 0.072). Time to first relapse was significantly prolonged with CsA versus placebo (p = 0.023), and PASI was significantly lower from weeks 4 to 16 in CsA recipients. In patients with moderate-severe psoriasis, the clinical success rate was significantly increased with CsA compared to placebo (69.9% vs 46.3%; p = 0.011), and significantly lower increases in PASI were observed from week 4 to week 24 (p < 0.05 vs placebo). CsA was well tolerated, with no differences in mean blood creatinine or blood pressure between CsA and placebo recipients. However, the high withdrawal rate (22.2% of randomized patients), which was not related to side effects, may have led to an overestimation of efficacy, but the study had a good statistical power (88% greater than that observed in similar studies, i.e. 80%). Week-end CsA administration was shown to prolong safely and effectively the time to first relapse in psoriasis patients.

Treatment of psoriasis with different dosage regimens of etanercept: preliminary results from the Tαranta Plastic Study Group.

This pilot open-label study is aimed to assess clinical response in psoriasis patients receiving diverse dose regimens of etanercept, consisting of the same global cumulative dose of etanercept administered over different treatment periods. Eligible patients were assigned sequentially in a 1:1 ratio to receive: etanercept 50 mg once weekly (QW) or 50 mg twice weekly (BIW) for 12 weeks. The final analysis included a total of 72 patients. At week 12 the Psoriasis Area and Severity Index (PASI) and Skindex-29 scores notably improved in both treatment arms, without significant differences between the two groups. The rate of patients attaining a PASI improvement >or= 50% (PASI 50) at week 12 was 92% in the high-dose group. In these patients, etanercept dosage was decreased to 50 mg QW from week 13, with persistence of the PASI 50 response at week 24 in all cases. Thereafter, treatment was discontinued up to week 36 and almost 30 % of patients experienced a gradual relapse of their psoriasis within this period. In the low-dose group, the PASI 50 response was observed in 75% of patients. These responders continued to be treated with etanercept 50 mg QW up to week 36 with persistence of the PASI 50 in 100% of cases at week 24 and 93% at week 36. In the low-dose regimen, 8 patients who did not respond at week 12 underwent dose escalation to 50 mg BIW for a further 12 weeks. At week 24, six of these patients gained the PASI 50 response, 4 of whom maintained the response up to week 36, after treatment discontinuation from week 24. Our results confirm that etanercept is very effective and well-tolerated in psoriasis and that the drug dosages and treatment duration may be modulated and adapted to clinical needs in a flexible way.

Adjuvant role of a new emollient cream in patients with palmar and/or plantar psoriasis: a pilot randomized open-label study.

Emollients are considered important adjunctive tools for the therapeutic management of psoriasis patients. In spite of the widespread use, the actual impact of emollients on psoriasis is far to be completely elucidated. The objective of this study was to evaluate the effect of a new emollient cream containing milk proteins and Glycyrrhiza glabra extracts in patients with palmar and/or plantar psoriasis treated with topical corticotherapy. This pilot open parallel-group trial was carried out in 40 patients with palmar and/or plantar psoriasis. Patients were randomized to receive monotherapy with mometasone furoate ointment, applied once daily to the palmoplantar lesions until remission and for a maximum of 4 weeks (N=20), or the same topical corticotherapy in combination with the emollient cream (N=20). The emollient was applied twice a day for 4 weeks. Clinical assessments were performed at baseline and 2 and 4 weeks after the start of treatment. All patients completed the study and showed a progressive improvement of their palmo-plantar psoriasis over the treatment period, achieving at week 4 a statistical significant reduction in the severity of all clinical signs (erythema, desquamation and infiltration) and in the surface area affected. The comparison between the two groups showed no differences in the mean average duration of corticosteroid therapy, whereas a significantly greater improvement of desquamation, surface area affected, and subjective symptoms was observed at week 4 in the group treated with the corticotherapy combined with the emollient as compared to patients who received the corticotherapy alone. This pilot experience suggests the importance of the adjuvant role of particular emollients in the management of psoriasis.

A multicenter open-label experience on the response of psoriasis to Adalimumab and effect of dose escalation in non-responders: the Aphrodite project.

There is much evidence to show the efficacy of adalimumab, a human monoclonal antibody targeting tumour necrosis factor-alpha, in the treatment of plaque psoriasis. In this open-label experience, 147 high-need patients suffering from plaque psoriasis, with a mean Psoriasis Area and Severity Index (PASI) of 18.8, and concomitant psoriatic arthritis (PsA) received subcutaneous injections of 40 mg of adalimumab every other week (EOW). This was actually the dosage regimen recommended for PsA, as the drug had not then been approved for psoriasis at the time of the patients enrolment. At week 12, an improvement of at least 50 percent of the PASI (PASI-50) was observed in 111 (77 percent) patients. Continuation of treatment in responders with adalimumab 40 mg EOW led to a sustained response, with the PASI-50 achieved by 97 percent of patients in the as-treated analysis at week 24 (PASI-75 in 82 percent and PASI-90 in 45 percent out of 109 patients who received EOW injections up to week 24). Thirty subjects who failed to attain the PASI-50 response at week 12 were treated with adalimumab 40 mg every week for a further 12 weeks. At week 24, 80 percent of these patients obtained a PASI-50 response after dose escalation. Tolerability was good in the majority of patients. Only two patients discontinued treatment because of an adverse event (repeated flu-like episodes and a pleuropericarditis of unknown origin, respectively).

Pemphigus vulgaris with circulating anti-desmoglein 3 and anti-BP180 antibodies: a case report and brief review of cases with coexistence of pemphigus vulgaris and bullous pemphigoid.

Pemphigus vulgaris (PV) and bullous pemphigoid (BP) are two autoimmune blistering diseases involving the skin and the mucous membranes characterized by circulating autoantibodies directed against desmosomal cadherins or antigens expressed in the basement membrane zone, respectively. The simultaneous presence of clinical and/or immunopathological features of PV and BP in the same patient has been reported in very few cases in the literature to date. Most of these cases had exclusive cutaneous involvement, while a minority showed concomitant oral lesions. We describe the case of a 59-year-old female patient with a 10-year history of refractory PV lesions limited to mucous membranes (conjunctiva, oral cavity and genital mucosa), which were controlled by the addition of mycophenolate sodium to oral prednisone. Immunofluorescence studies revealed findings consistent with PV, whereas enzyme-linked immunosorbent assay revealed circulating anti-BP180 antibodies in association with anti-desmoglein 3 antibodies. The significance and relevance of this finding are briefly discussed, in light of the literature data.

Methyl-aminolevulinate photodynamic therapy for the treatment of actinic keratoses and non-melanoma skin cancers: a retrospective analysis of response in 462 patients.

AIM: Topical photodynamic therapy (PDT) with methyl-aminolevulinate (MAL) is widely used for the management of actinic keratoses (AK) and non-melanoma skin cancers (NMSCs). The authors report the results of a retrospective chart review showing the cumulative four-year experience with MAL-PDT in a hospital outpatient setting. METHODS: The medical records selected concerned all patients who completed the MAL-PDT regimen (one single session for AK and two sessions one week apart for NMSCs) and who underwent post-treatment assessments over a follow-up period of at least 12 months. RESULTS: Present case series included a total of 462 patients: 210 patients with AK, 228 subjects with 348 basal cell carcinomas (BCCs), 213 of nodular type (nBCC) and 135 of superficial type (sBCC), 17 patients with Bowen's disease and seven with squamous cell carcinoma. On the whole, following a single session, complete clearance of AK was achieved in 79% of patients at three months and in 68.1% at 12 months. As concerns BCCs, regardless of the clinical type, a complete response was observed in 71% of lesions at three months, with a rate of recurrence at 12 months of 15%. The risk of both initial treatment failure and recurrence was higher for nBCCs than sBCCs. Our results, even if obtained in very few cases, indicate that Bowen's disease is very responsive to MAL-PDT, unlike microinvasive or invasive SCC. Treatment was generally well tolerated. CONCLUSIONS: Our experience confirms that MAL-PDT is a valid approach to patients with AK, BCC and Bowen's disease, with an acceptable tolerability profile and a very low risk of complications.

Photoallergic contact dermatitis.

Photoallergic contact dermatitis (PCD) is a delayed-type hypersensitivity cutaneous reaction in response to a photoantigen applied to the skin in subjects previously sensitized to the same substance. For the development of PCD, irradiation with ultraviolet (UV) radiations, usually UVA, is required to create a complete antigen, and the culprit substance needs to be within the skin at the time of UVA exposure. The incidence of PCD in the general population is unknown and is considered uncommon. Epidemiological data have been obtained from studies performed using photo-patch tests in patients with suspected photodermatoses in tertiary care outpatient units. Prevalence of PCD over time has been also dependent on prescription and/or usage patterns of potential photosensitizers, and was particularly high in the past, causing mini-epidemics in some countries because of the widespread use of halogenated salicylanilides and other photosensitizing compounds. Many topical substances with photosensitizing properties are currently available, with the most important ones being sunscreen agents and nonsteroidal antiinflammatory drugs. The diagnosis of PCD, in patients with a history of photosensitivity and especially with an eczematous form of photodermatosis, should be confirmed by photo-patch testing.