An HTLV-1 carrier with sporadic late-onset nemaline myopathy accompanied by skin lesions indicating indolent adult T-cell leukemia/lymphoma and Sjögren's syndrome: a case report and literature review.

Sporadic late-onset nemaline myopathy (SLONM) is a rare acquired myopathy. Herein, we report a rare case of co-occurring SLONM, indolent adult T-cell leukemia/lymphoma (ATL), and Sjögren's syndrome (SS) in a 60-year-old woman who was a human T-cell leukemia virus type 1 (HTLV-1) carrier. She presented with sub-acute proximal muscle weakness and chest erythema. Muscle biopsy revealed perivascular inflammation and accumulation of nemaline bodies in the atrophic fibers. Skin biopsy indicated indolent ATL. Analysis of specific antibodies and salivary gland biopsy led to a SS diagnosis. CD4-positive T cells expressing FoxP3 and CCR4, which constitute an HTLV-1-infected cell signature, were observed in all three tissues. Her muscular and cutaneous symptoms responded well to steroids. This case suggests a potential link between HTLV-1 latent infection and reactivation and SLONM development and progression. We review the clinicopathological features of SLONM across various etiologies, providing valuable insights into this rare condition.