A radiological diagnosis of a mediastinal lymphoma was proffered.

An ultrasound-guided biopsy of the mediastinal mass was performed.

Histological diagnosis

Macroscopy: two cores of cream and hemorrhagic tissue measuring 16 mm and 13 mm. 

Microscopy: two core biopsies of skeletal muscle and fibrous tissue which are infiltrated by a lymphoid proliferation comprising large malignant cells. Some of which are mummified and some have large nucleoli. No classical Hodgkin Reed Sternberg cells are seen. The background comprises prominent eosinophils with plasma cells and small lymphocytes. Apoptosis is prominent. Immunohistochemistry shows strong membranous and perigolgi staining with CD30. The large cells are also positive with MUM1. These larger cells are negative with CD20 and OCT2. PAX5 is largely negative but there is occasional weak staining. MUM1 is positive for BCL6 is negative within these large cells. Ki67 shows a high proliferation rate within the malignant large cells. CD21 and CD23 show residual follicular dendritic cell population. CD15 is strongly positive within the larger cells. There is no expression of Cyclin D1 or CD5 within the malignant population.

Conclusion: Thoracic mass - classic Hodgkin lymphoma: likely nodular sclerosing subtype.