(449) Extremely High Procalcitonin Related to Leukemia Cutis Without Concomitant Sepsis

Introduction: Procalcitonin (PCT) is a well-known biomarker for infection and is highly sensitive and specific in differentiating bacterial infection from systemic inflammation in acutely ill patients. Noninfectious causes of spuriously high levels of PCT are rare. We describe a case of extremely high PCT levels (>200 ng/mL) in a patient diagnosed with leukemia cutis without concomitant sepsis.

Description: An 82-year-old man recently diagnosed with transformed chronic lymphocytic leukemia to acute myelogenous leukemia (AML) presented with fever and left lower extremity pain and swelling with no history of trauma. Physical examination was notable for swelling and erythema of the left leg without any open wounds or purulent drainage. Laboratory data revealed a white blood count (WBC) of 5100, creatinine of 1.0 mg/dL, and PCT on 0.62 ng/mL. He was started on broad-spectrum antibiotics. Blood cultures on admission were negative. On day 2, his WBC rose to 12,100. A repeat PCT was markedly elevated at 340 ng/mL. Given the high suspicion for sepsis, the antimicrobial regimen was broadened, and additional infectious workup was done including fungal and viral serologies and cultures, all of which were negative. He developed transient hypotension requiring vasopressor and was admitted to the ICU. On day 4, another PCT was obtained and remained elevated at 240 ng/mL. In search for an alternative pathology, a skin biopsy from the left leg was obtained and was consistent with leukemia cell infiltration (leukemia cutis). The patient continued to have daily fevers with negative cultures. He was started on hydroxurea for the AML and with rasburicase for hyperuricemia and tumor lysis syndrome. He was ordered for gilteritinib (oral selective FLT3 inhibitor) for progressive AML but unfortunately his condition worsened, and his family opted for comfort care measures only and he expired.

Discussion: Our case highlights the importance for searching for noninfectious etiologies in any patient with hematological malignancy presenting with an extremely high PCT level with negative infectious disease workup and no clinical improvement despite broad spectrum antimicrobial therapy. We surmised that the markedly elevated PCT in our patient was related to the severe inflammatory response from the cutaneous involvement of AML.