Paraneoplastic leukemoid reaction in a patient with metastatic adenocarcinoma of the lung

Abstract

Paraneoplastic syndromes in lung malignancies can lead to leukemoid reaction with an elevation of eosinophils, neutrophils, and monocytes. The elevation of these three lineages together due to paraneoplastic syndromes has not been described in literature yet.

Metastatic BRAF V600E-Mutated Adenocarcinoma of the Lung Presenting as Extreme Neutrophilia and Eosinophilia

“…Infection should initially be excluded since it is more common than PLR as a cause of secondary leukocytosis. Other causes of secondary leukocytosis include tuberculosis and Clostridium difficile , drugs such as corticosteroids, ethylene glycol intoxication, acute hemolysis, and miscellaneous etiologies [ 3 , 6 ]. In patients who have PLR, granulocyte-colony stimulating factor (G-CSF) is directly secreted by tumor cells into the host’s circulation, thus leading to cytokine-mediated granulocytosis [ 6 ].…”

“…Bone marrow examination in patients with PLR is usually hypercellular with myeloid hyperplasia, without an increase in blast percentage, and left-shifted myelopoiesis with toxic granulation [ 3 ]. In our patient, bone marrow biopsy showed hypercellular marrow and metastatic carcinoma involving 15% core cellularity.…”

“…Eosinophilia is defined as an increase in peripheral blood eosinophils, an absolute eosinophil count (AEC) of >500 cells/μL, and white blood cells (WBCs) that originate from the granulocytic lineage [ 2 , 3 ]. The incidence of eosinophilia in malignant tumors is about 1%.…”

“…Cancers of the lung and bronchus accounted for 12.4% of all new cancer cases and 21.7% of all cancer deaths in 2021 [ 1 ]. Lung cancers have been associated with mild leukocytosis [ 2 , 3 ]. BRAF mutations are found in 1-4% of non-small cell lung cancer (NSCLC) cases and are rarely seen with marked neutrophilia and eosinophilia [ 4 ].…”

“…Malignancy‐induced paraneoplastic leukemoid reaction (PLR) is difficult to diagnose since several secondary causes need to be ruled out [ 3 ]. If the underlying malignancy is not clinically apparent, PLR can be mistaken for myeloproliferative neoplasms, thereby altering the patient’s management [ 5 ].…”