69-year-old male with a large mediastinum mass.

Procedure: CT-guided needle core biopsy.

Gross: The specimen consists of multiple soft, tan-white, cylindrical tissue fragments, ranging from less than 0.1 to 1.0 cm. in length, and measuring less than 0.1 cm. in diameter.

Micro: Sections show a high-grade cellular malignant tumor with features of small cell neuroendocrine carcinoma. Tumor is composed of trabeculae and solid sheets of intermediate sized tumor cells with scanty eosinophilic cytoplasm with high nuclear/cytoplasmic ratio. Nuclei are elongated, hyperchromatic, with condensed coarse chromatin pattern. There is no squamous or adenocarcinoma differentiation. There is a large area of tumor necrosis. The tumor shows high mitotic index.

IHC stain:

Pankeratin Positive
CK 7 Positive
TTF-1 Positive, diffuse
CD 45 (LCA) Negative
Synapotophysin(SYP) Positive, patchy