Circulating mesothelial cells following multiple ribs fractures

Abstract

Non-haematopoietic cells can be seen rarely in peripheral blood films either due to procedural contamination or as truly circulating cells. Various types of malignant non-haematopoietic cells are examples of the latter. Here we report a case of circulating mesothelial cells in a Saudi male who presented on his 19th birthday, following a road traffic accident in which he had suffered extensive trauma. Chest radiography showed multiple fractured lower ribs on the right side and bilateral pleural effusions. A computerized tomography scan confirmed the pleural effusions and showed fractures of the right 8th, 9th and 10th ribs with free fragments projecting into the thorax; in addition, there was a large haemorrhagic lung contusion involving the right lower lobe and a compression fracture of the D3 with a fracture also of the adjacent transverse process. A full blood count showed: white cell count 11AE1 · 10/l, neutrophil count 9AE6 · 10/l, haemoglobin concentration 99 g/l and platelet count 90 · 10/l. A coagulation screen showed a prothrombin time of 15AE8 s (normal range 12–16 s) and activated partial thromboplastin time 33 s (normal range 28–40 s). Unexpectedly a blood film showed mesothelial cells (Figures). To confirm their identity, blocks of a peripheral blood sample were prepared for electron microscopy and immunohistochemistry. The cells expressed desmin, calretin, epithelial membrane antigen and WT1 and were negative for CD38, CD45, CD68 and cadherin. By day 2 the mesothelial cells had disappeared from the circulation. Circulating large cells (>50 lm) include megakaryocytes, carcinoma cells and possibly Hodgkin cells; there may also be clusters of malignant cells or of endothelial cells. These cells have characteristic morphology differentiating them from each other and from normal circulating cells. With the exception of megakaryocytes, the presence of any of these cells requires further testing including tissue and bone marrow biopsy. The presence of circulating large nonhaematopoietic cells in the peripheral blood requires careful morphological examination of cellular details to identify the nature of these cells; however, this needs to be accompanied by assessment of clinical data and close follow-up with repeated blood films to demonstrate the disappearance or persistence of such cells.