Cutaneous Granulomatosis and Class Switching Defect as a Presenting Sign in Ataxia-Telangiectasia: First Case from the National Iranian Registry and Review of the Literature.

Ataxia-telangiectasia (A-T) is a rare autosomal recessive syndrome characterized by progressive cerebellar ataxia, oculocutaneous telangiectasia, immunodeficiency and cancer predisposition, caused by mutations in the ataxia telangiectasia mutated (ATM) gene. The clinical and immunological manifestations of A-T are very heterogeneous, especially at an early age, leading to frequent misdiagnosis. Cutaneous granulomas with unknown pathogenesis occur uncommonly in a minority of A-T patients. We herein report an unusual case of a 13-year-old girl with A-T who presented severe clinical manifestations, including multiple granulomatous lesions of the skin and a class switch defect phenotype. This patient is the first Iranian A-T case with cutaneous granulomatosis and immunodeficiency. In addition, the literature on skin granulomas in all previously reported A-T patients is reviewed indicating an increased frequency of elevated IgM level and female dominancy in this selected group of patients.