Bone marrow metastasis of small cell carcinoma of the lung mimicking Burkitt lymphoma/leukemias

which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. A 64-year-old man was admitted for the evaluation of severe lower back and bilateral leg pain that had persisted for a week. On spinal magnetic resonance images, diffuse abnormal signal intensity involving the whole bone marrow with patch enhancement was noted. CBC revealed the following: leukocyte count of 6.85×10 9 /L; hemoglobin of 13.6 g/dL; and platelet count of 32.0×10 9 /L. On bone marrow aspiration smear, diffuse infiltration of monotonous cells was found, although the clustering pattern was not distinct. Each cell had a high nuclear/cytoplasmic ratio, was slightly variable cell size, round to oval in shape, and had a slightly irregular nucleus with dispersed chromatin, rare indistinct nucleoli, and deeply basophilic cytoplasm with abundant vacuoles (A). In cytogenetic study, no t(8;14) was detected and a complex karyotype with many double minutes (10-75 per cell) was found (B). In FISH analysis, these double minutes were revealed as c-MYC gene amplification (C). Bone marrow biopsy revealed hypercellular marrow with a starry sky-like appearance (D). In immunohistochemistry of biopsy material, synaptophysin was positive (E). We accordingly concluded bone marrow metastasis of small cell carcinoma. Thereafter, we could find primary origin of the small cell carcinoma at the lung by computed tomography.