The motility of the internal anal sphincter includes myogenic tone, relaxation mediated by nitric oxide and purinergic P2Y1 receptors, and contraction mediated by cholinergic motor neurons and sympathetic fibers. The motility of the longitudinal muscle is limited to a contraction mediated by cholinergic neurons, suggesting that longitudinal muscle contracts during relaxation of the internal sphincter, shortening the anal canal. Nicotinic, muscarinic, and serotoninergic receptors might be therapeutic targets for anal motor disorders.
We describe a 60-year-old woman with primary Sjögren's syndrome, mixed cryoglobulinaemia and cutaneous leucocytoclastic vasculitis who developed generalized hypohidrosis with a markedly decreased sweating response to pilocarpine chloride. Skin biopsies demonstrated dense peri-eccrine lymphocytic infiltrates in the lower reticular dermis, with glandular atrophy. From previous studies it is evident that although patients with Sjögren's syndrome commonly have skin dryness, a lymphocytic hidradenitis has been documented only in a few cases. The histological findings in this case support the role of autoimmune hidradenitis in the development of hypohidrosis in Sjögren's syndrome.
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