Liquid biopsy perspectives in pleomorphic carcinoma of the lung: case report

Liquid biopsy has recently made it possible to use minimally invasive testing to examine tumor-derived material released into peripheral blood, including circulating tumor cells (CTCs), extracellular vesicles (EVs), and circulating tumor deoxyribonucleic acid (ctDNA). Lung pleomorphic carcinoma (PC) is an extremely rare and severe form of cancer. Although resection tissues are the basis for PC diagnosis in everyday practice, tiny biopsies and cytologic specimens might potentially raise suspicions. Because PC may show varied expression of conventional carcinoma markers, it can be particularly challenging to differentiate sarcomatoid (i.e., spindle cell or giant cell) components from other tumor forms, such as sarcomatoid mesothelioma and other sarcomas. We think that defining a more specific context to better understand patient prognosis may be aided by the discovery of blood molecular markers in PC.

We present two cases of patients underwent major lung resection at our center with a diagnosis of PC of the lung; specifically, according with 8th TNM edition, case 1 showed a final pathological stage pathological tumor-node-metastasis (pTNM): pT1cN0G3LV0R0, and case 2 showed a stage pTNM: pT3N0G3LV0R0. Patients were both discharged after surgery with no postoperative complications. Oncologists suggested a 5-year clinical and radiological follow-up, however case 1 patient is free from recurrence at the moment, while case 2 patient died for brain recurrence 10 months after surgery. Immediately after surgical resection, patient's specimens were sent to the pathology unit. The pathologist, without affecting the accuracy of histological diagnosis, selected representative tissue samples and sent them at 4 ℃ in specific media, to Bioscience Laboratory, IRCCS IRST "Dino Amadori" for tissue analysis. Additionally, blood samples collected before surgery were sent for the characterization of CTCs and EVs.

To better characterize the potential relationship between the presence of CTCs, EVs and high grade of malignancy and any subsequent connection to death and/or recurrence, we think that liquid biopsy, which involves the identification and characterization of tumor-derived elements, may serve as future approach and tool not only in NSCLC but also in each specific histotype as for lung PC.