Anti-Nuclear Antibody-Negative Lupus Nephritis or Post-Infectious Glomerulonephritis: Diagnostic Dilemma in a Young Male.

Proliferative lupus nephritis (LN) is histologically characterized by endocapillary hypercellularity and large immune deposits on light microscopy. Immunofluorescence shows almost all immunoglobulins and complement staining. The presence of antinuclear antibodies (ANA) is important for diagnosing systemic lupus erythematosus (SLE). Absence of ANA rules out the possibility of SLE according to the 2019 European League Against Rheumatism/American College of Rheumatology classification criteria for SLE. We report a young boy with fever, nephrotic-nephritic syndrome and pancytopenia consistent with hemophagocytic lymphohistiocytosis. Renal biopsy was consistent with LN; however, his initial ANA was negative. In view of pathological features of LN and persistent pancytopenia, high dose steroid therapy was started. Repeat ANA, done during the illness, turned positive. In this report, we describe the relevance of pathological patterns and the uncertainties of ANA positivity in making a diagnosis of SLE.