Lupus enteritis and peritonitis presenting as initial manifestations of systemic lupus erythematosus: diagnostic challenge in tuberculosis-endemic regions - case report.

INTRODUCTION AND IMPORTANCE: Systemic lupus erythematosus (SLE) is a chronic multisystem autoimmune disease with heterogeneous manifestations. Gastrointestinal involvement, such as lupus enteritis, is rare and often presents with nonspecific abdominal symptoms and is associated with significant morbidity and mortality. Peritoneal involvement with ascites as an initial manifestation is also among the rarest presentations of SLE. In tuberculosis (TB)-endemic regions, these presentations may mimic abdominal TB, complicating timely diagnosis. CASE PRESENTATION: A 23-year-old male presented with worsening epigastric pain, loose stools, weight loss, and generalized joint pain without swelling. He had been treated for presumed tuberculous peritonitis 18 months earlier. Examination revealed bilateral lower lung dullness and a distended, mildly tender abdomen. Laboratory studies showed mild leukocytosis with a left shift and elevated C-reactive protein. Ascitic fluid analysis revealed 370 cells/mm3 (85% neutrophils), elevated lactate dehydrogenase, a low serum-ascitic albumin gradient, and a high glucose level. Antinuclear antibodies and anti-double-stranded DNA antibodies were positive, with reduced complement levels. Abdominal CT demonstrated "water-target sign." After a diagnosis of lupus enteritis and serositis, the patient received corticosteroids and hydroxychloroquine and showed marked improvement. CLINICAL DISCUSSION: Lupus enteritis and peritonitis are rare gastrointestinal and serosal manifestations of SLE that may mimic infectious diseases, such as abdominal TB, in endemic regions. Early recognition and prompt immunosuppressive therapy can prevent life-threatening complications, including bowel ischemia and perforation. CONCLUSION: Lupus enteritis and peritonitis can present as the initial manifestations of SLE, posing a diagnostic challenge in TB-endemic regions. Clinicians should consider SLE in the differential diagnosis of unexplained enteritis and peritonitis once common causes are excluded.