1. MedPix Medical Image Database COW - Case of the Week Case Contributor: Hugh M Dainer Affiliation: National Capital Consortium

2. MedPix No: 12568 - History Pt Demographics: Age = 42 y.o. Gender = woman 42 year-old with history of large PE treated with anticoagulation for 6 months. Now with recurrent chest pain. ER requests reassessment of clot burden. Downloaded by (-1)

3. MedPix No: 12568 - EXAM & LABS Noncontributory - Labs Normal

4. Pulmonary Embolism Previous imaging of the patient during an inpatient stay for gynecological surgery 6 months earlier demonstrate a near-occlusive pulmonary embolism of the right main pulmonary artery. Downloaded by (-1)

5. Pulmonary Embolism - Resolved Repeat imaging of the patient during new visit to ER demonstrates resolution of prior pulmonary embolism. Downloaded by (-1)

6. Left Paratracheal mass - Castleman Disease - Hyaline Vascular Variant Imaging of the apices (which were not visualized on the prior exam) shows a large left paratracheal mass extending from just above the aortic arch to just below the left thyroid lobe. The mass measures ~10 x 3 x 2 cm. Downloaded by (-1)

7. Left Paratracheal mass - Castleman Disease - Hyaline Vascular Variant Imaging of the apices (which were not visualized on the prior exam) shows a large left paratracheal mass extending from just above the aortic arch to just below the left thyroid lobe. The mass measures ~10 x 3 x 2 cm. Downloaded by (-1)

8. Left Paratracheal mass - Castleman Disease - Hyaline Vascular Variant Whole body PET-CT fusion image in the frontal plan has been cropped to show the upper body. Note activity at the base of the neck (brown fat), left paratracheal region (mass of interest) and unexpected node in the AP window. Downloaded by (-1)

9. Left Paratracheal mass - Castleman Disease - Hyaline Vascular Variant 1. Localizer on the left - 2. PET image at the top - 3. CT image in the middle - 4. Fusion PET-CT image at the bottom - Lesion of interest is shown to coincide directly with a focus of abnormal activity. Again note activity at the base of the neck (brown fat) and activity in the AP window (unexpected lymph node). Downloaded by (-1)

10. Left Paratracheal mass - Castleman Disease - Hyaline Vascular Variant 1. Localizer at the far left - 2. Axial PET image on the left - 3. Sagittal PET image in the middle - 4. Frontal PET image at the right - High activity is noted within the left paratracheal mass as localized in three dimensions. SUV max measurement is 4.45 SUV (greater than 2.5 is considered concerning for malignancy). Downloaded by (-1)

11. FINDINGS 1. Old CTA-large right pulmonary artery embolism-apices not imaged2. New CTA-clot resolved-apices imaged - mass along the left aspect of trachea = ~10 x 3 x 2 cm3. PET-mass size corresponds to CT - significant activity (4.45 SUVs)-other regions at base of neck correspond to brown fat-single focus of high activity in AP window likely node

12. DIFFERENTIAL DIAGNOSIS What is your Differential Diagnosis? Lymphoma - Tuberculosis - Castleman Disease - Exophytic thyroid nodule - Thymoma

13. Diagnosis: Castleman Disease - Hyaline Vascular Variant Dx Confirmed by: Excisional Biopsy

14. DISCUSSION Given that the pathological diagnosis is hyaline vascular variant, the patient will likely be cured by this single intervention. It is unlikely that her Castleman Disease was related to her symptoms, however, this cases demonstrates that the previous standard method of performing CTA can lead to missed diagnoses as the lung apices are not imaged. Given the speed of modern scanner and the presence of fan-beam geometry, scans of the entire chest can now be performed without significant radiation increase.