PMC9238202_01
Images of a thymic epidermoid cyst in a 37-year-old female.. A. Posteroanterior chest radiograph shows consolidation in the left lower lung area, suggesting pneumonia. The lateral chest radiograph (left) shows a suspicious nodular opacity in the anterior mediastinum (arrow).. B. Axial, coronal, and sagittal chest CT images demonstrate a 2.8 cm oval-shaped, well-defined mass with suspicious thin walls (arrows) in the anterior mediastinum. On the axial non-enhanced CT image, the mass shows a heterogeneous attenuation and the peripheral portion of the mass reveals a focal high attenuation (arrowhead). On the axial contrast-enhanced CT images, no definite contrast enhancement is observed in any part of the mass (open arrowhead). In addition, there is no evidence of the surrounding mediastinal fat invasion.. C. Surgical specimen shows a spherical, well-encapsulated, hard mass within the retrosternal area.. D. The mass measures 2.5 cm x 2 cm x 2 cm and is a well-encapsulated unilocular cyst, full of abundant keratin debris.. E. Histological finding shows that the cyst is lined by keratinized squamous epithelium (arrow) within the thymic tissue (asterisk) (hematoxylin and eosin stain, x 100).
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Incidentally, on the left lateral chest radiograph, there was a suspicious nodular opacity in the anterior mediastinum (Fig. 1A). Moreover, there was a 2.8 cm sized, oval shaped, well-defined mass with suspicious thin walls at the left side, located in the anterior mediastinum (Fig. 1B). During surgery, the lesion showed a relatively spherical shape and a well-encapsulated structure (Fig. 1C). Gross examination of the surgical specimen revealed a unilocular cyst measuring 2.5 cm x 2 cm x 2 cm, filled with keratin debris within normal thymic tissues (Fig. 1D). Microscopically, the cyst was lined by keratinized stratified squamous epithelium and diagnosed as an epidermoid cyst (Fig. 1E).