1. Approach to a Mass of Unknown Significance Location Kinetics Systemic Manifestations

2. Differential Diagnosis of an Anterior Mediastinal Mass Thymoma Germ Cell Tumor/Teratoma Lymphoma

3. Shipp M et al. N Engl J Med 2005;352:1697-1704 Differential Diagnosis of an Anterior Mediastinal Mass

4. Malignancy Infection Granulomatous Disease Benign Tumors Others

5. Our Patient

6. Familial Adenomatous Polyposis (FAP) Autosomal Dominant Disease High penetrance (almost ~100) Mean age of onset 16 100-1,000s of colonic polyps Average age of colon cancer is 39 Accounts for ~1% of all colorectal cancers

7. Genetics of FAP Classic FAP caused by mutation in APC gene Accounts for 90% of cases Discovered at Johns Hopkins by Kenneth Kinzler and Bert Vogelstein Genetic Test commercially available

8. FAP Unaffected

9. Management of FAP Surveillance with annual colonoscopies Colectomy is recommended when polyps are large, dysplastic or with villous histology Patients with small and/or sparse polyps can be followed and schedule colectomy after graduation from High School Total proctocolectomy with ileoanal pouch Subtotal colectomy with ileorectoal anastomsosis

10. Classic Metastatic Colon Cancer to Lung

11. MalignancyAbsolute Lifetime Risk (%) Colon100 Duodenum3.0–5.0 Thyroid2.0 Brain (Meduloblastoma)2.0 Ampullary1.7 Pancreas1.7 Hepatoblastoma1.6 Gastric0.6* Extracolonic Malignancies in FAP patients

12. DESMOID TUMORS Benign Slow Growing Tumors Develop in 10-15% of patients with FAP Typically intra-abdominal and arise at sites of trauma (ie Surgery) Composed of spindle cells and abundant fibrous stroma

13. Final Differential Diagnosis Atrial Myxoma Indolent Lymphoma Proliferative Fibrosing Mediastinitis

14. DIAGNOSIS Desmoid Tumor arising in site of Surgical trauma (CABG in 2002) in a patient with FAP