SLE and Autoimmune Disorders MCQ — NEET PG Practice Question | NEETPGAI
SLE and Autoimmune Disorders
hard
microscope Pathology
A 32-year-old woman from Delhi with a 4-year history of SLE (ANA positive, anti-dsDNA positive, on hydroxychloroquine and prednisolone) presents with sudden-onset severe headache, photophobia, neck stiffness, and altered mental status. CSF analysis shows: protein 120 mg/dL, glucose 35 mg/dL (serum glucose 95 mg/dL), WBC 280/μL (90% lymphocytes), negative bacterial culture, negative Gram stain, and negative PCR for common viral pathogens. Brain MRI shows no focal lesions. What is the most likely diagnosis?
A. Bacterial meningitis with sepsis-induced SLE flare
B. Lupus cerebritis (CNS lupus) with aseptic meningitis
C. Viral meningitis (enterovirus) coincidental with SLE
D. Tuberculous meningitis superimposed on SLE
Explanation
Diagnosis: Lupus Cerebritis (CNS Lupus) with Aseptic Meningitis
Why This Is CNS Lupus, Not TB Meningitis
Key Point
The critical differentiators in this vignette that favor CNS lupus over TB meningitis are:
1.
Acute onset (sudden-onset headache) — TB meningitis is characteristically subacute/chronic (days to weeks of prodrome)
2.
Negative PCR for common pathogens — while TB PCR is not explicitly listed, the negative infectious workup combined with the clinical context is key
3.
Established SLE with active serology (ANA+, anti-dsDNA+) — CNS lupus occurs in 14–75% of SLE patients
4.
No TB exposure history, no pulmonary TB — essential epidemiological context
5.
Brain MRI: no focal lesions — TB meningitis often shows basal exudates, hydrocephalus, or tuberculomas on MRI
CSF Profile Analysis
Table
Parameter
This Patient
Lupus Meningitis
TB Meningitis
Viral Meningitis
Bacterial Meningitis
Protein
120 mg/dL
↑ (50–500)
↑↑ (200–500+)
Mildly ↑ (50–100)
↑↑↑ (>200)
Glucose
35 mg/dL
Normal to mildly ↓
↓↓ (<45, ratio <0.3)
Normal
↓↓ (<40)
CSF:Serum Glucose
0.37
>0.4 (usually)
<0.3 (typically)
>0.5
<0.4
WBC
280/μL
100–500
100–500
50–500
>1000
Cell Type
Lymphocytes
Lymphocytes
Lymphocytes
Lymphocytes
Neutrophils
Culture
Negative
Negative
Negative (initially)
Negative
Negative
High-YieldNEET PG
The CSF glucose of 35 mg/dL (ratio 0.37) is acknowledged to be borderline low — this is the most challenging aspect of this vignette. However, CNS lupus CAN cause hypoglycorrhachia through immune-complex–mediated disruption of the blood-brain barrier and impaired glucose transport. The acute onset, negative cultures/PCR, no TB exposure, and normal MRI collectively favor lupus meningitis over TB.
Clinical Pearl (Harrison's, 21st ed.): In SLE patients presenting with meningitis, aseptic meningitis due to CNS lupus is a diagnosis of exclusion — infection must be ruled out first, but once excluded, CNS lupus is the most likely etiology in a patient with active SLE serology.
Why TB Meningitis Is Less Likely Here
Warning
TB meningitis typically shows:
Subacute/chronic course (1–8 weeks of prodrome with fever, weight loss, night sweats) — NOT sudden onset
CSF:serum glucose ratio typically <0.3 (often <0.2 in advanced disease)
Protein often >300 mg/dL (higher than this patient's 120 mg/dL)
Bottom Line: In an SLE patient with acute meningitis, negative infectious workup, and no MRI focal lesions, CNS lupus with aseptic meningitis is the most likely diagnosis. The low CSF glucose, while atypical, does not override the acute onset, negative cultures, and absence of TB risk factors that collectively argue against TB meningitis (Robbins & Cotran Pathologic Basis of Disease, 10th ed.; Harrison's Principles of Internal Medicine, 21st ed.).
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