A 37-year-old woman presented with mediastinic syndrome, pericardial effusion, diffuse lymphoadenopathy, and severe pancytopenia. Peripheral blood smear showed sporadic nucleolated large cells recalling poorly differentiated lymphoma cells. Bone marrow smears were characterized by a diffuse infiltration by undifferentiated cells forming syncitia and resembling the ones detected in the periphery. These abnormal cells were negative for lymphoid and myeloid markers on flow cytometry. Latero-cervical lymph node biopsy as well as bone marrow trephine showed diffuse infiltration by poorly differentiated cells which turned out to be negative for CD45, CD99, Myeloperoxidase, CD34, CD15, and S-100 while being strongly positive for neuron-specific enolase on histochemistry. This picture shows a circulating neuroendocrine tumor cell (on the right, beside a normal lymphocyte) (MGG ×100). Of note, this circulating tumor cell shows features very similar to those of lymphoma cells.