Hechos y controversias en la enfermedad mixta del tejido conectivo / Facts and controversies in mixed connective tissue disease

La enfermedad mixta del tejido conectivo (EMTC) es una enfermedad reumática autoinmunitaria sistémica (ERAS) caracterizada por la asociación de manifestaciones clínicas de lupus eritematoso sistémico (LES), esclerosis sistémica cutánea (ESC) y polimiositis-dermatomiositis en presencia de títulos elevados de anticuerpos anti-U1-RNP en el suero de los pacientes. Sus principales síntomas son la poliartritis, el edema de manos, el fenómeno de Raynaud, la esclerodactilia, la miositis y la hipomotilidad esofágica. Actualmente, la mayoría de los autores acepta que la EMTC es una entidad independiente, pero algunos mantienen que estos pacientes podrían presentar una ERAS, definida en su fase precoz como LES o ESC, o ser, en realidad, un síndrome de solapamiento de la ERAS (AU)

Mixed connective tissue disease (MCTD) is a systemic autoimmune rheumatic disease (SARD) characterised by the combination of clinical manifestations of systemic lupus erythematosus (SLE), cutaneous systemic sclerosis (SSc) and polymyositis-dermatomyositis, in the presence of elevated titers of anti-U1-RNP antibodies. Main symptoms of the disease are polyarthritis, hand oedema, Raynaud's phenomenon, sclerodactyly, myositis and oesophageal hypomobility. Although widely discussed, most authors today accept MCTD as an independent entity. Others, however, suggest that these patients may belong to subgroups or early stages of certain definite connective diseases, such as SLE or SSc, or are, in fact, SARD overlap syndromes (AU)

Pregnancy in mixed connective tissue disease.

This article discusses fetal and maternal morbidity in women who have mixed connective tissue disease.

Pregnancy outcome in nephrotic syndrome with mixed connective tissue disease.

We describe two pregnancies of a young woman with mixed connective tissue disease. In June 1983, she was diagnosed as having Raynaud's phenomenon, arthralgia, and proteinuria. She then developed nephrotic syndrome. Methylprednisolone was initially prescribed at a large dose of 1 g/day which was slowly tapered to 5 mg/day. The proteinuria disappeared. During both pregnancies (the first beginning in December 1988 and the second in May 1992), the patient was placed on a prednisolone maintenance dose (5 mg/day). Both neonates were born healthy at term with no complications. Continuing prednisolone may be useful in pregnant women, and aggressive treatment to prevent mixed connective tissue disease exacerbation may be appropriate during pregnancy.

Usefulness of antinuclear antibody testing to screen for rheumatic diseases.

OBJECTIVE: To assess the usefulness of the indirect immunofluorescence antinuclear antibody test (FANA) using human laryngeal epithelial carcinoma cells as nuclear substrate, to screen for childhood rheumatic diseases. STUDY DESIGN: A review of all FANA tests performed on children at British Columbia's Children's Hospital between 7 March 1991 and 31 July 1995. RESULTS: FANA tests were positive at titres of 1:20 or greater in 41% of all subjects tested, and in 65% of all subjects in whom the diagnosis was obtained. FANA positivity occurred in 67% of those with a rheumatic disease, compared with 64% of those with a non-rheumatic disease (p = 0.4). More girls had high titre FANA positivity than boys independent of whether or not they had a rheumatic disease (p = 0.05). At a screening serum dilution of 1:40 a positive test has a sensitivity of only 0.63, and a positive predictive value of only 0.33 for any rheumatic disease. For systemic lupus erythematosus (SLE), mixed connective tissue disease (MCTD), or overlap syndrome at a screening dilution of 1:40 the test has a very high sensitivity of 0.98, but a very low positive predictive value of only 0.10, the test having slightly better characteristics for boys than girls. CONCLUSION: Although a negative FANA test makes a diagnosis of SLE or MCTD extremely unlikely, a positive test even at moderately high titres of 1:160 or higher is found so frequently in children without a rheumatic disease that a positive result has little or no diagnostic value. It is suggested that a screening serum dilution of 1:160 or 1:320 would increase the usefulness of the test, by decreasing false positive tests, without significantly increasing false negative tests for SLE or MCTD, and would have the potential for considerable cost savings.