Internal Medicine

0521779407-14 CUNY1086/Karliner 0 521 77940 7 June 4, 2007 21:16

958 Mediastinal Masses

differential diagnosis

■Differential diagnosis depends on location

■Anterior Mediastinum

➣Thymic neoplasms, esp thymoma:

most are benign

evidence of myasthenia gravis in 10–50% of patients with thy-

moma

require tissue for diagnosis

➣Germ cell tumors:

10–12% of mediastinal masses; 80% benign

Teratoma and teratocarcinoma:

2/3 symptomatic (cough, pain, dyspnea)

smooth, rounded

may contain teeth, bone

Seminoma:

men, 20–30 y old

SVC obstruction common

extend locally, metastasize to bone

Embryonal cell carcinoma, choriocarcinoma:

often secrete HCG, alphaFP, CEA

➣Lymphoma:

10–20% of mediastinal masses

➣Thyroid:

ectopic thyroid=10–20% of masses

identifiable by radioactive iodine scanning

➣Parathyroid:

adenomas, cysts, carcinoma

99m Technitium sestamibi

➣Mesenchymal tumors, tissue:

lipomas, fibromas, mesotheliomas, lymphangiomas, lipoma-

tosis

➣Diaphragmatic hernia (Morgagni)

➣Primary cancer

■Middle Mediastinum

➣Lymphadenopathy:

>1 cm=abnormal

from lymphoma, metastases, granulomatous inflammation

➣Developmental cysts:

10–20% of mediastinal masses

pericardial, bronchogenic, enteric