The mucous membranes (or mucosa) are linings of ectodermic origin, covered in epithelium, that line various body cavities and internal organs. It is at several places continuous with skin: at the nostrils, the lips, the ears, the genitourinary area, and the anus. The viscid secretion of the mucous membranes is termed mucus (note the spelling difference).
Mucousmembrane plasmacytosis is a rare, idiopathic condition consisting of a dense plasma-cell infiltrate of the mucousmembranes.
Mucousmembrane plasmacytosis of the upper aerodigestive tract is a rare, benign disorder in which the mucousmembranes are infiltrated by plasma cells.
Mucousmembrane lesions are present in one-third of patients with secondary syphilis, and histology can show superficial and deep perivascular infiltrate of plasma cells, lymphocytes and macrophages distributed in a bandlike pattern in the dermis, accompanied by psoriasiform epidermal hyperplasia and hyperkeratosis [28].