Table 2.

Characteristic clinical manifestation of thymomas and differential diagnosis with other causes of mediastinal masses

	Speed of development	Associated clinical manifestations	Characteristic signs
Thymoma	Long course or indolent	Compressive symptoms: Chest pain, dyspnea, dysphagia, vena cava syndrome	Laboratory abnormalities: Anti-acetylcholine receptor antibodies (common if associated with MG), hypogammaglobulinemia, erythropenia, pancytopenia
		Neurological autoimmune disorders: MG, myotonic dystrophy, limbic encephalitis, peripheral neuropathy
		Hematologic autoimmune disorders: Red-cell aplasia, pernicious anemia, erythrocytosis, pancytopenia
Thymic carcinoma	Rapid growth	Collagen autoimmune disorders: Systemic lupus erythematosus, rheumatoid arthritis, Sjogren's syndrome, scleroderma	PET-CT: Thymoma types A, AB, B1-2: Low uptake.
		Endocrine disorders: Multiple endocrine neoplasia, Cushing's syndrome, thyroiditis	PET-CT: Type B3 thymoma and thymic carcinoma: High uptake, with loss of bilobar structure of the thymus
		Autoimmune deficiencies: Hypogammaglobulinemia, T-cell deficiency
Lymphoma	Fulminant onset	Dermatological disorders: Pemphigus, Lichen planus	Elevated LDH
		“B” symptoms: Fever, weight loss, sweating
Teratoma	Slow development	Lymphadenopathy. Asymptomatic or compressive symptoms of long duration	CT: Heterogeneous mass, with cystic component and fat/calcifications
Germ cell tumors	Rapid development	Testicular mass	Seminoma: Elevated beta-HCG
			No seminoma: Elevated beta-HCG and AFP
Thymic hyperplasia	Indolent	Asymptomatic	PET-CT: Elevated uptake in mass that maintains the thymic bilobar structure

MG: Myasthenia gravis; PET-CT: Positron emission tomography-computed tomography; LDH: Lactate dehydrogenase; HCG: Human chorionic gonadotropin; AFP: Alpha fetoprotein.