Chronic urticaria versus dermatomyositis in a case of T- cell large granular lymphocytic leukemia

Abstract

Aim: The reported case involved a complicated diagnostic path, not only because of the usual difficulties specific to chronic urticaria but, also because the trigger was a T-cell large granular lymphocytic leukemia (T-LGLL), a rare type of leukemia with an indolent course whose etiology is still not well known. This leukemia is also known for its propensity to cause autoimmune diseases. The aim of this study was to identify whether the muscle damage was caused by dermatomyositis or by T-LGLL. Methods: After elevated muscle enzyme levels had been discovered magnetic resonance imaging (MRI) revealed muscle damage. Consequently, a muscle biopsy was performed in a targeted manner. In addition to muscle biopsy, transmission electron microscopy and anti-CN1A antibody testing were performed. Results: MRI of the lower limbs and pelvic girdle indicated moderate fibroadipose substitution in many muscles, moderate edema in others. No involvement of the shoulder girdle and upper limbs. Histological examination of the muscle fibers showed an “inflammatory myopathy with isolated phagocytotic fibers.” Inclusion-body myositis, which is known to be associated with chronic T-LGLL was excluded. On the same biopsy transmission electron microscopy confirmed inflammatory myopathy and anti-CN1A antibodies were positive. DNA extracted from the muscle of the micro-rearrangement for the y-chain of the TCR identified on the DNA extracted from peripheral blood was positive. Conclusions: Conclusions: Chronic urticaria was an indication of immunoproliferative disease. Myositis was the pathology due to T-LGLL, and dermatomyositis was excluded.