Lupus nephritis (LN) is a serious and common complication of systemic lupus erythematosus (SLE) that predisposes to significant morbidity and mortality. Studies show that prompt diagnosis and treatment improves patient survival. We present a case of a 49-year-old female with an atypical presentation of LN who initially presented with new-onset hypertension, edema, arthritis, serositis and recently diagnosed leukocytoclastic vasculitis who later developed acute kidney injury, hematuria and nephrotic syndrome. Laboratory testing showed mixed cryoglobulinemia and elevated perinuclear anti-neutrophil cytoplasmic (p-ANCA) and myeloperoxidase (MPO) antibodies. SLE-related serologies were negative. Kidney biopsy showed diffuse proliferative global glomerulonephritis with a full-house nephropathy pattern on immunofluorescence suggestive of LN. Due to high clinical suspicion and renal biopsy findings, she was treated for LN with prompt renal response to immunosuppression. Cryoglobulins, p-ANCA and MPO titers normalized and the negative SLE serologies remained negative. Literature review on antinuclear antibody (ANA)-negative and seronegative LN revealed the following patient presentations: (1) renal-limited or renal and extra-renal manifestations of SLE with negative serologies and (2) renal and extra-renal manifestations of SLE with negative serologies at presentation who develop positive serologies later in follow-up. Both groups represent a unique and challenging cohort of patients who may require longer follow-up and further testing to rule out other glomerular diseases that may mimic LN on renal biopsy. The absence of SLE-related serologies should be weighed against a high pre-test probability of ANA-negative or seronegative LN. If highly suspected, the patient should be treated promptly with close monitoring.