title: Acquired C1q deficiency caused by monoclonal paraproteinaemia.
abstract: Acquired C1q deficiency secondary to anti C1q auto-antibodies may result in the hypocomplementaemic urticarial vasculitis syndrome and may also be seen in active systemic lupus erythematosus. Some patients with acquired C1 inhibitor deficiency are found to have an underlying malignancy, most commonly lymphoma. We report a case of a 40-year-old man presenting with a lupus-like illness with acquired C1q deficiency secondary to a monoclonal paraprotein in the presence of splenic lymphoma with villous lymphocytes. His clinical symptoms correlated with the presence of the paraprotein. Relapse coincided with a rise in the paraprotein and fall in C1q, C3 and C4. There was no improvement in his clinical condition following combination chemotherapy. He remains on oral prednisolone.
authors.affiliation: Centre for Rheumatic Diseases, Glasgow Royal Infirmary, Scotland, UK.
authors.forename: M M
authors.initials: MM
authors.lastname: Gordon
authors.forename: N
authors.initials: N
authors.lastname: Lucie
authors.forename: D
authors.initials: D
authors.lastname: Porter
mesh_terms: D000328:Adult; D015922:Complement C1q / Q000032:analysis / Q000172:deficiency*; D003176:Complement C3 / Q000032:analysis; D003181:Complement C4 / Q000032:analysis; D005938:Glucocorticoids / Q000627:therapeutic use; D006801:Humans; D008223:Lymphoma / Q000150:complications* / Q000188:drug therapy / Q000276:immunology; D008297:Male; D010265:Paraproteinemias / Q000150:complications* / Q000188:drug therapy / Q000276:immunology; D011239:Prednisolone / Q000627:therapeutic use; D013160:Splenic Neoplasms / Q000150:complications* / Q000188:drug therapy / Q000276:immunology
chemical_list: D003176:Complement C3; D003181:Complement C4; D005938:Glucocorticoids; D015922:Complement C1q; D011239:Prednisolone