Background: Systemic lupus erythematous (SLE) is an autoimmune, episodic, and chronic disease that can affect multiple organs in the body and consequently it can present with variety of sign and symptoms. Hypercalcemia is a considered to be a rare presentation in patients with systemic lupus erythematous. In this case report we present a patient with SLE flare up who presented with hypercalcemia, which her overlapping manifestations endured a challenging diagnosis of lymphoma.Case Presentation: A 41-year-old man with a ten-year history of SLE presented to us with symptoms of SLE flare up. During laboratory evaluation, high calcium level was detected which was unresponsive to the treatment. Bone marrow revealed marginal B cell lymphoma as the ultimate diagnosis. He was started on R-CHOP chemotherapy regimen, and reported relative improvement in clinical and laboratory conditions during follow-ups.Conclusion: Our case is the first report of concurrent SLE flare up, with a diagnosis of lymphoma and a primary clinical presentation of hypercalcemia. Physicians should be aware of the fact that patients with SLE flare up can present with hypercalcemia and lymphoma as concomitant conditions that needs further exploration.