Mediastinal small cell carcinoma with liver and bone marrow metastasis, mimicking lymphoma

Figure 1 Computed tomography findings. A 6.6 cm × 4.3 cm mediastinal mass was observed.

Figure 2 Endoscopic ultrasound findings. A: Echoview showed a large mediastinal mass; B: Liver nodules with target-like appearance were also observed.

Figure 3 Fine-needle aspiration cytology was performed.

Figure 4 Histopathologic findings. A and B: Cell-block preparation from fine-needle aspiration of the mediastinal mass showed numerous small, individual, round cells with hyperchromatic nuclei, scarce cytoplasm, and frequent mitotic features. Rare instances of nuclear molding were also observed (hematoxylin-eosin staining, magnification × 10 and × 40, respectively); C and D: Immunohistochemical study revealed that the tumor cells were positive for AE1/AE3 (C) and chromogranin A (D; magnifications × 40).

Figure 5 Bone marrow biopsy showed extensive infiltration by cohesive sheets of small, round cells with fine granular chromatin and scarce cytoplasm.