Use of an Interferon-γ Release Assay in the Detection of Latent Tuberculosis in Dermatology: A Descriptive Analysis.

With the increasing use of biologic therapy in psoriasis, it is becoming more important to identify and treat latent tuberculosis (TB) infection (LTBI). Tuberculin skin test (TST) has been traditionally used to detect LTBI, but interferon-γ release assays (IGRAs), such as the T-SPOT.TB test (T-Spot), are increasingly being used in its place. The indications and results of 51 T-Spot tests performed at the National Skin Centre in Singapore between 2008 and 2010 were analyzed and compared with TST results, decision on LTBI treatment, and previous use of immunosuppressants. T-Spot was most commonly performed as part of a prebiologic workup in patients with psoriasis. A total of 14 (27.5%) results were positive, and no patients had features of active TB. Ten of these patients also underwent TST, five of whom had negative TST results. Six patients (11.8%) had equivocal results with T-Spot test. This study shows poor concordance between T-Spot test and TST. A high incidence of equivocal results in IGRA may limit the utility of the T-Spot test.

Chronic actinic dermatitis in Asian skin: a Singaporean experience.

BACKGROUND/PURPOSE: To study the characteristics of chronic actinic dermatitis (CAD) in a heterogeneous group of Singaporean patients. METHODS: The photobiologicial features of all patients phototested and diagnosed with CAD from January 2005 to December 2009 were examined retrospectively. RESULTS: Fifty-eight patients were diagnosed as having CAD. The mean age at diagnosis was 62 years (range 35-83). Forty-one were (70.7%) Chinese, six (10.3%) Indians, eight (13.8%) Malays, and three (5.2%) Others. Forty-seven were (81.0%) male and 11 (19.0%) were female. Forty-nine (84.5%) had Fitzpatrick skin phototype IV and nine (15.5%) had phototype V. Three of 26 (11.5%) tested for human immunodeficiency virus were positive. The face, neck, and forearms were most commonly affected. Thirty-two patients (55.2%) had reduced minimal erythema dose (MED) to both ultraviolet B (UVB)and ultraviolet A (UVA), 23 patients (39.7%) had lowered MED to UVB only, while three (5.1%) had reduced MED to UVA only. Patients were followed up for a mean of 16.8 months. All were treated with photoprotection and topical steroids; however, a few required oral immunosuppression with partial improvement. CONCLUSION: In Singapore, CAD was seen more commonly in elderly Chinese males of Fitzpatrick skin phototype IV. Reduced MED to both UVB and UVA was the most common phototest finding.

The role of topical traditional chinese medicaments as contact sensitisers in chronic venous leg ulcer patients.

INTRODUCTION: Leg ulcers are a chronic condition affecting the older population. In Singapore, the use of topical traditional Chinese medicaments (TTCM) is common amongst those older than 65 years of age. We study the role of TTCM as contact sensitisers in patients with chronic venous leg ulcers and its impact in the clinical management of these patients. MATERIALS AND METHODS: Patients with chronic leg ulcers attending the Wound and Ulcer Clinic at the National Skin Centre (NSC) between October 2005 and April 2006 were patch-tested to the NSC TTCM series. They were also patch-tested for other allergens from the NSC Standard Series, Medicament Series, Steroid Series and wound dressings. RESULTS: A total of 44 patients were patch-tested. Seventeen of the 44 (38.7%) patients were using or had used at least 1 TTCM. Seven patients (15.9%) had at least 1 positive patch test (PT) reading to TTCM, giving a sensitisation rate of 41% (7 of 17). A significantly high proportion of the patients, 94.1% (16 of 17) with a positive history of TTCM usage had at least 1 positive PT reading compared to those without a history of TTCM usage, 45.8% (11 of 24). CONCLUSION: TTCM play an important role as contact sensitisers in our patients with chronic venous leg ulcers and may be a significant factor in non- or poor-healing leg ulcers. In such patients, a history of TTCM usage should be sought for and patch testing should include the commonly used TTCM where relevant.

Contact sensitization in patients with chronic venous leg ulcers in Singapore.

Contact sensitization rates are high in patients with chronic venous leg ulcers. Allergic contact dermatitis poses a significant hindrance to the healing of the wounds. There are no published studies examining the rate of contact sensitization in Asian patients. Our objective was to determine the rate of contact sensitization in patients with chronic venous leg ulcer in Singapore and the variation in the common allergens based on local practices in comparison with Western countries. 44 patients were patch tested to the National Skin Centre standard series, steroid series, medicaments, topical Chinese medicaments, and to modern wound dressings used. The overall rate of contact sensitization was 61.4%. The common allergen groups were topical antibiotics (18.2%) and topical traditional Chinese medicaments (TTCM) (15.9%). Individually, colophony (11.3%), Saw Hong Choon skin ointment (Kam Bo Med, Hong Kong, Hong Kong) (11.3%), Balsam of Peru (9.1%), and povidone iodine (9.1%) were among the most frequent allergens. The sensitization rate among users of TTCM was notably high (41%). A high rate of contact sensitization was found in our study, similar to previous reports from the West. TTCM play a major role as possible allergens in our patients. In Asian patients, a history of its usage should be elicited, and patch testing should include the commonly used TTCM where possible.