Phototesting was performed using the

Phototesting was performed using the following light sources: a UV 801 KL (Waldmann, Villingen-Schwenningen, Germany) equipped with four TL 20 W/12 fluorescent tubes (spectral output 285–350 nm, peak 310–315 nm; Philips, Eindhoven, The Netherlands) for UVB and six UV-A Cleo 40 W fluorescent tubes (spectral output 315–400 nm, peak 355–365 nm; Philips) for UVA. The back of each patient was exposed to five graded doses of UVB ranging from 20 mJ/cm2 to 100 mJ/cm2, with an increment of 20 mJ/cm2 and five graded doses of UVA ranging from 3 J/cm2 to 15 J/cm2, with an increment of 3 J/cm2. The MED was defined as the smallest exposure dose required to produce a minimally perceptible erythema with well demarcated borders. Erythema responses were read 24 hours after irradiation; if no response was observed at 24 hours, a second reading at 48 hours would be taken. If needed, a photopatch test was performed according to the guidelines of the International Contact Dermatitis Research Group to exclude photosensitive dermatitis or photoallergic contact dermatitis.
Results
Discussion The diagnosis of CAD is suggested by the clinical findings, most commonly a chronic eczematous rash on the sun exposed areas, and corroborated by phototesting, which characterizes the action spectrum and degree of photosensitivity. When necessary, histology of the lesional metalloproteinase is used to exclude other disorders. In this study, we retrospectively reviewed the clinical features, phototest results, and treatment of CAD in a Taiwanese population. Our study showed that CAD commonly affected elderly men, with a remarkable male predominance and a mean age at diagnosis of 58.6 years, in line with previous reports. The lack of female patients in this study might be due to the small sample size. There has been evidence that CAD may occur in young patients with atopic dermatitis; however, the patient in our study who presented the disease at a relatively young age (Patient 2, age 28 years) did not have atopic diathesis. Immunoglobulin (Ig)E level was measured in three of the patients. Patient 2 had an IgE level of < 2 IU/mL. Patients 7 and 11 had slightly elevated IgE levels of 329 IU/mL and 170 IU/mL, respectively (normal range, 0–100 IU/mL). Some authors have noticed an association between increased sun exposure and CAD. Therefore, we also list the occupation of these patients in Table 1. Abnormal photosensitivity is the hallmark of CAD. Historically, vulva has been suggested that all CAD patients have a reduced MED to UVB, the majority also have a reduced MED to UVA, and a minority respond to the visible wavelengths as well. In addition, UVA sensitivity dissociated from UVB sensitivity has been implicated as a relative indicator of drug induced photosensitivity or photoallergic contact dermatitis (PACD). However, lowered MED to UVA only in otherwise typical CAD cases has been increasingly reported. In our study, the majority of the patients (53.3%) had reduced MED to both UVB and UVA, in keeping with the common observations in the literature. Interestingly, a significant portion (40.0%) of our patients had reduced MED to only UVB, compared with just 6.7% to only UVA. This was similar to the study results in Singaporean and Korean populations. By contrast, other studies found reduced MED to only UVA more common than reduced MED to only UVB in the Greek, Australian, and United States populations. The reason for the discrepancy remains unclear and ethnic or geographical factors may contribute to it. Patch and photopatch tests are ancillary tools in patients with suspected CAD to exclude allergic contact dermatitis (ACD) and PACD. Up to 75% CAD patients were reported to have positive reactions in patch or photopatch tests. In our institute, we do not perform patch and photopatch tests routinely if the patient does not have a history of exposure to an allergen or photosensitizer. This is a shortage that the possibility of ACD/PACD or concurrent ACD/PACD and CAD cannot be excluded in this study. Patient 11 was a construction worker having contact history to formaldehyde and melamine; patch testing with the standard tray and his contactants showed positive reactions to potassium dichromate and nickel sulfate. Patient 13 also received photopatch tests in order to exclude drug-induced photosensitivity and PACD and the results were negative.