Approach to a Mass of Unknown Significance

Location

Kinetics

Systemic Manifestations

Differential Diagnosis of an Anterior Mediastinal Mass

Thymoma

Germ Cell Tumor/Teratoma

Lymphoma

Shipp M et al. N Engl J Med 2005;352:1697-1704

Differential Diagnosis of an Anterior Mediastinal Mass

Differential Diagnosis of an Anterior Mediastinal Mass

Malignancy

Infection

Granulomatous Disease

Benign Tumors

Others

Our Patient

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

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

FAP Unaffected

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

Classic Metastatic Colon Cancer to Lung

Malignancy Absolute Lifetime Risk (%)

Colon 100

Duodenum 3.0–5.0

Thyroid 2.0

Brain (Meduloblastoma) 2.0

Ampullary 1.7

Pancreas 1.7

Hepatoblastoma 1.6

Gastric 0.6*

Extracolonic Malignancies in FAP patients

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

Final Differential Diagnosis

Atrial Myxoma

Indolent Lymphoma

Proliferative Fibrosing Mediastinitis

DIAGNOSIS

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