Association between HLA-B*58:01 allele and severe cutaneous adverse reactions with allopurinol in Han Chinese in Hong Kong.

BACKGROUND: Allopurinol has been reported as a common cause of severe cutaneous adverse reactions (SCARs). Recent studies in various populations suggest that HLA-B*58:01 is a strong genetic marker for allopurinol-induced SCAR, especially in populations with a high frequency of HLA-B*58:01. OBJECTIVES: To confirm the association link between HLA-B*58:01 and hypersensitivity reactions attributed to allopurinol use in Han Chinese patients in Hong Kong. METHODS: We performed a case-control study to investigate whether the HLA-B*58:01 allele predisposes to allopurinol-induced SCAR in Han Chinese patients in Hong Kong. The HLA-B*58:01 genotyping was performed in 20 patients with allopurinol-induced SCAR or erythema multiforme major (EMM; n = 1) and in 30 patients tolerant to allopurinol. RESULTS: All of the 19 patients with allopurinol-induced SCAR examined but not the patient with EMM carried HLA-B*58:01 whereas only four (13%) of the control patients had this allele. The positive rate of the HLA-B*58:01 was significantly higher in the cases than in the allopurinol-tolerant control group [odds ratio (OR) 123·5, 95% confidence interval (CI) 12·8-1195·1; P < 1 × 10(-4) ] and was even higher after removal of the patient with EMM (OR 229·7, 95% CI 11·7-4520·4). The sensitivity and specificity of the HLA-B*58:01 allele for prediction of allopurinol-induced SCAR were 100% and 86·7%, respectively. CONCLUSIONS: This study confirmed the strong association between the HLA-B*58:01 and allopurinol-induced SCAR in Hong Kong Han Chinese patients. A screening test for the HLA-B*58:01 allele should effectively reduce the risk for allopurinol-induced SCAR in Chinese populations.

Generalized granuloma annulare associated with gastrointestinal stromal tumour: case report and review of clinical features and management.

The paraneoplastic variant of granuloma annulare (GA) is a rare cutaneous manifestation of underlying malignancy that is most commonly associated with systemic lymphoma. We report an interesting case of a patient with gastrointestinal stromal tumour (GIST) of the stomach presenting with extensive generalized GA. GIST was diagnosed 2 months after the diagnosis of GA. Resolution of the GA was seen 1 month after surgical excision of GIST. The close correlation of the clinical courses of these two rare diseases suggests that their coexistence was more than a coincidental finding. This case highlights the importance of excluding paraneoplastic GA, especially in cases where the skin manifestations are extensive and resistant to treatment.