Paraneoplastic Hyperleukocytosis Mimicking Hematologic Malignancy Revealing a Localized Lung Cancer

Hyperleukocytosis, leukemoid reaction caused by malignant peritoneal mesothelioma: a case report and review of literature

Paraneoplastic leukemoid reaction (PLR)-induced hyperleukocytosis remains a critical diagnostic challenge. Malignant peritoneal mesothelioma, known for its nonspecific clinical presentation, often evades early detection. We report a 75-year-old male with cirrhosis presenting with fever (38.2°C), progressive ascites, leukocytosis (109.9×109/L), and elevated CRP (247.41 mg/L). Initial diagnosis of spontaneous peritonitis failed to explain the leukocytosis, prompting bone marrow examination, including cytomorphology and genetic analysis, which turned out do not support a diagnosis of leukemia or myeloproliferative neoplasms. Subsequent peritoneal biopsy confirmed diffuse malignant peritoneal mesothelioma. Despite prompt diagnosis, the patient developed progressive multi-organ dysfunction and died on day 14. This case underscores the imperative to consider PLR as a potential cause of hyperleukocytosis in oncological contexts, rather than attributing it solely to hematological malignancies. Moreover, it highlights the importance of considering malignant peritoneal mesothelioma in the differential diagnosis of unexplained ascites and peritoneal thickening. Additionally, we propose the hypothesis that glucocorticoids may hold therapeutic potential in the management of PLR.

Paraneoplastic leukemoid reaction in a localised squamous cell oesophageal cancer with paracrine G-CSF production

A 51-year-old-man presented with symptoms and baseline investigations suggestive of an infective process. Most strikingly, there was a pronounced neutrophil predominant leucocytosis. Lack of a clinical and biochemical response to empirical antibiotic therapy, prompted imaging for a deep-seated infective process, incidentally uncovering a gastro-oesophageal junction tumour. Resection of the tumour was followed by rapid resolution of the leucocytosis. He remains in clinical remission since tumour resection and adjuvant chemotherapy. Cancer-associated leukemoid reactions in non-disseminated tumours are rare. The role of polymorphonuclear (PMN) leucocytes both in the peripheral blood and the tumour itself is discussed herein. There is increasing recognition of the importance of the non-cancer cellular components of the tumour microenvironment. Myeloid suppressor cells are a subset of PMN leucocytes which play a role in tumour progression.The role of these cells and granulocyte colony-stimulating factor is highlighted in this case.