Renal vein thrombosis with hydronephrosis in seropositive rheumatoid arthritis with hepatitis B reactivity: a diagnostic challenge suggestive of renal tuberculosis

Abstract

Rheumatoid arthritis (RA) is associated with an increased susceptibility to infection, while immunosuppressive treatment may further complicate the recognition and management of tuberculosis (TB). Renal TB is an indolent form of genitourinary TB that may present with non-specific constitutional and urinary manifestations and can cause obstructive uropathy. Renal vein thrombosis (RVT) is an uncommon vascular complication that may occur in the setting of systemic inflammation or infection. We report a 65-year-old man with recently diagnosed seropositive RA and hepatitis B surface antigen positivity who presented with six months of intermittent low-grade fever, constitutional symptoms and symmetrical inflammatory polyarthritis, followed by left flank pain, intermittent haematuria and bilateral lower-limb swelling. Laboratory evaluation showed anaemia, markedly elevated inflammatory markers and strongly positive rheumatoid factor and anti-CCP antibodies. HBsAg was positive, while HBV DNA was undetectable. Contrast-enhanced CT demonstrated a bulky left kidney with moderate hydronephrosis, pelvicalyceal dilatation, PUJ obstruction and left RVT with extensive collateral formation. Urine culture was sterile and renal function was preserved. Subsequent urine CBNAAT detected Mycobacterium tuberculosis and showed rifampicin susceptibility, establishing renal TB in the appropriate clinical and radiological context. The patient was treated with anticoagulation, RA-directed therapy, supportive measures and subsequently drug-susceptible antitubercular therapy. This case emphasizes the diagnostic challenge posed by overlapping inflammatory, infective and thrombotic manifestations and highlights the importance of considering renal TB in patients with hydronephrosis, urinary symptoms and unexplained RVT, particularly when routine bacterial cultures are sterile.