Ans. (b) PleuritisRef: Harrisons Principle of Internal Medicine 20th Ed; Page No- 2520Most Common Complication in SLE* Cutaneous Manifestations:# The most common acute SLE rash: Butterfly" rash# Most common chronic dermatitis in lupus: Discoid lupus erythematosus (DLE)* Vascular Occlusions: Myocardial infarctions are primarily manifestations of accelerated atherosclerosis.* Pulmonary manifestation: Pleuritis with or without pleural effusion.* Cardiac manifestations: Pericarditis.* Hematologic Manifestations: Anemia* Renal Manifestations: Nephritis* CNS Manifestations: The most common manifestation of diffuse CNS lupus is cognitive dysfunction, including difficulties with memory and reasoning.NoteOther pulmonary Complications* Pulmonary infiltrates are seen active SLE and it is very difficult to distinguish from infection on imaging studies.* Interstitial inflammation is a life-threatening pulmonary manifestation leading to fibrosis, shrinking lung syndrome, and intra-alveolar hemorrhage.* Pulmonary arterial hypertension occurs in a small proportion of SLE patients.Cardiac complications* More serious cardiac manifestations are myocarditis and fibrinous endocarditis of Libman-Sacks.* A patient has SLE if four or more of these 11 criteria are present at any time.Diagnostic criteria for SLEMucocutaneous signs (each counts as one)* Malar rash* Photosensitivity rash* Oral ulcers rash* Discoid rashArthritisPresent in 90 percent of patients; non-erosiveCardiac & PulmonaryPericarditis, myocarditis, Pleuritis (most common pulmonary finding), pleural effusion, pneumonitis, pulmonary HypertensionHematologic (Any blood involvement counts as 1 criteria)Hemolytic anemia, leukopenia, lymphopenia, thrombocytopeniaRenalIt benign from Proteinuria >0.5g/ day to end stage renal disease; such as:- Cellular casts, Glomerulonephritis, azotemia, pyuria, uremia, HTNCerebralSeizures, psychosis (may be subtle), meningitis TIA, cerebrovascular accidentSerology* ANA. It is 95 % sensitive but not specific; almost all patients with SLE have elevated serum ANA levels.* Anti-ds DNA (60-70%) or anti-Sm (Smith) (10-20%). The presence of either of these is diagnostic of SLE--very specific (but obviously not sensitive)NoteEach of the serologic abnormalities counts as 1 criterion. Hence, if the person has joint pain, a rash, and both an ANA and DS DNA, that patient would have 4 criteria.Points to RememberDiagnostic Test for SLE* Best initial test: ANA* Most specific test: Anti-DS DNA (60-70%) or anti-Sm (Smith) (10-20%)..* Rule of thumb- ANA positivity is a must in SLE diagnosis.* ANA negativity twice rules out SLE. Even though ANA positivity cannot confirm SLE - negativity can rule out.Note* There is no ANA negative SLE. But there is ANA negative scleroderma* Also Drug induced lupus - secondary to Quinidine/ Minocycline tends to be ANA negative.