What question did this study set out to answer?

To report a case of a posterior mediastinal gastrointestinal stromal tumor (GIST) in an elderly male.

February 22, 2026Pathology0 citations

A case of posterior mediastinal gastrointestial stromal tumour

DSDa young Song BCBruce Tsz Chun Chau TBTina Baillie

Key Points

To report a case of a posterior mediastinal gastrointestinal stromal tumor (GIST) in an elderly male.
CT imaging revealed a subcarinal mass resembling a neurogenic tumor.
Macroscopical and microscopical examination of the tumor was performed.
Immunohistochemical assays evaluated relevant markers on tumor tissue.
The mass was well-circumscribed with low mitotic activity.
Immunohistochemical stains were positive for CD117 and negative for other markers like S100 and ALK.
Findings supported the diagnosis of gastrointestinal stromal tumor.

Abstract

Case: A male in 70s had an incidental subcarinal mass on CT. The ovoid, well-circumscribed mass (64 × 50 × 41 mm) showed heterogeneous peripheral enhancement and displaced the oesophagus anteriorly, favouring a neurogenic tumour. Macroscopically, the specimen comprised lobulated tan fragments (up to 95 mm; 90 g). Microscopically, the mass comprised spindle-cell arranged in sweeping fascicles arising within/adjacent to muscularis propria. Mitotic activity was low (1/5 mm 2 ), with no necrosis. Immunohistochemical stains showed diffuse KIT (CD117), DOG1 and CD34 positivity; negative for pancytokeratin, S100/SOX10, desmin/SMA, STAT6, ALK, myogenin and β-catenin; retained H3K27me3 and Ki-67 ∼5%. Subcarinal lymph nodes were negative for malignancy. Findings supported oesophageal gastrointestinal stromal tumour (GIST).

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