GPR: 2020 - Week 49

Clinical history

52 year-old man with a mediastinal mass.

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thymoma

Most common solitary lesion of the mediastinum in adults with peak age of presentation at ages 40-60
May be incidental and asymptomatic or malignant and symptomatic
40% are associated with paraneoplastic syndromes such as myasthenia gravis (among others)
Cell of origin is thymic epithelium
Grossly appear lobulated, grey to tan-white, often encapsulated, and may exhibit cystic change
The specimen pictured here was metastatic histologic subtype B3 (~60% 10 year survival)

intimal sarcoma

Most commonly arises from the intima of the pulmonary artery or thoracic aorta with a mean age of presentation in the mid 60s.
Symptoms may arise from obstruction of blood flow
Commonly presents as metastatic disease with 20% 1-year survival
Usually form nodular, multifocal plaques on the intimal surface and directly obstruct or embolize
Comprised of extensive necrosis with otherwise poorly differentiated pleomorphic cells

lymphoblastic lymphoma

Commonly presents as a rapidly enlarging anterior superior mediastinal mass in 2-5 year-olds with rare presentations in adults over the age of 60
Often causes SVC syndrome in association with rapid enlargement
Non-specific white to tan-white, solid, fleshy gross appearance
Produces diffuse sheets of immature lymphoid cells that can be confused with WHO type B1 thymoma. Pancytokeratins help distinguish the epithelioid origin of the latter.

cross-section

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Nicholson, A. G. (2015). WHO Classification of Tumours of the Lung, Pleura, Thymus and Heart. United States: International Agency for Research on Cancer.
Campo, E., Harris, N. L. (2017). WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues. United States: International Agency for Research on Cancer.

This week's Gross Pathology Roundup was presented by Cameron Ray Smith on MD, PhD.