When immunohistochemistry misleads: pleural masses in a young adult with prior soft tissue sarcoma

Figures

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  FIGURE 1. Frontal chest radiograph demonstrating a large homogeneous opacity occupying the majority of the left hemithorax with associated lumbar dextroscoliosis. Rib cortices are intact; no periosteal reaction is identified.

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  FIGURE 2. Axial contrast-enhanced computed tomography (CT) images (5-mm slice thickness; mediastinal reconstruction algorithm) demonstrating a) a large heterogeneous pleural-based mass in the left upper hemithorax and b) left lower hemithorax, bridged by a band of anterior pleural soft tissue. No underlying rib destruction is present. A separate pleural-based nodule is seen in the right upper hemithorax (b).

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  FIGURE 3. a, b) Axial 2-fluoro-2-deoxy-d-glucose (FDG) positron emission tomography (PET)-computed tomography (CT) images (3-mm slice thickness) demonstrating FDG-avid pleural-based masses in a) the left upper hemithorax (maximum standardised uptake value (SUVmax) 5.8) and b) left lower hemithorax (SUVmax 8.3), with predominantly peripheral FDG avidity and central photopenic areas consistent with necrosis. Rib cortices are intact bilaterally. FDG avidity of the vertebral bodies is noted; this was not designated as pathological in the formal PET-CT report, which documented no additional abnormal FDG-avid foci beyond those described. This pattern may represent physiological marrow activity or reactive marrow change; vertebral biopsy was not performed given the established diagnosis, the treatment response, and the absence of a formal report designation of vertebral metastases. c) Coronal FDG PET-CT image (3-mm slice thickness) demonstrating an FDG-avid lytic lesion in the right ilium (SUVmax 4.4), consistent with osseous metastasis.

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  FIGURE 4. a) Low-power photomicrograph (original magnification ×100; haematoxylin and eosin stain) demonstrating a cellular spindle cell neoplasm in short interlacing fascicles. b) High-power view (×200) showing ovoid-to-spindle cells with inconspicuous nucleoli and scant eosinophilic cytoplasm; no Homer Wright rosettes were identified. Immunohistochemistry: c) Bcl2 (diffuse positive), d) pan-cytokeratin (positive), e) TLE1 (strong nuclear) and f) Ki-67 proliferation index 20%.