Thymoma differential diagnosis

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Amr Marawan, M.D. [2] Ahmad Al Maradni, M.D. [3] Nouman M.K, M.D.[4]

Overview

Thymoma must be differentiated from other diseases such as thymic carcinoma, mediastinal germ cell tumor,thymic masses,lymphoma and substernal thyroid.

Differential Diagnosis

Thymoma must be differentiated from other diseases as:

Diseases	Site	Histology Findings and Lab Tests				Clinical Features
	Mediastinal Part	Cell Organization	Tumor Cells	Lymphoid Cells	Additional Tests	General Symptoms	Obstructive symptoms	Additional Features
Mediastinal Germ Cell Tumor	Anterior	Non-adhesive	Cell with large nuclei and prominent nucleoli	Mature looking,small	PLAP+ Serum AFP	Chest pain, Cough Difficulty breathing Weight loss	Superior vena cava syndrome	Post obstructive pneumonia
Thymic masses	Anterior	Varies	Depend on mass type	Varies with type	Depend on type	Fever Night sweats Weight loss(depend on mass type)	Stridor Superior vena cava syndrome Facial Swelling Odynophagia	Obstructive effect can cause Horner syndrome
Lymphoma	Anterior,middle	Non-adhesive	Immature lymphoid cells(Non-Hodgkin Lymphoma), Classical Reed Sternberg Cell and its variant(Hodgkin Lymphoma)	Immature(Non-Hodgkin lymphoma) Mature,small(Hodgkin lymphoma)	LCA+, Light chain restriction in B-NHL, CD15+,CD30+ in Hodgkin Lymphoma	Fever Weight loss Night sweats Shortness of breath	Phrenic nerve palsy Hoarseness Superior vena cava syndrome	Pleural Effusion Pericardial effusion
Thyroid	Anterior	Varies	Hurtle cells,prominent nucleoli,abundant cytoplasm	Non-Hodgkin type is more common in Thyroid lymphoma	Antithyroid peroxidase antibodies, Antithyroglobulin antibodies	Symptoms of hypothyroidism(cold intolerance,weight gain,constipation etc) or Hyperthyroidism (heat intolerance,weight loss,diarrhea etc)	Positional dyspnea Choking sensation Wheezing Superior vena cava syndrome	Vocal cord palsy Horner Syndrome

Thymomas Vs Thymic Carcinomas:

• The following table shows the important differences between thymomas and thymic carcinomas:

Differential diagnosis of thymomas types A, AB, B and thymic carcinomas.

Other differentials

Thymoma must be differentiated from other similar conditions which lead to multiple endocrine disorders such as autoimmune polyendocrine syndrome, POEMS syndrome, Hirata syndrome, Kearns–Sayre syndrome and Wolfram syndromes.

Disease	Addison's disease	Type 1 diabetes mellitus	Hypothyroidism	Other disorders present
APS type 1	+	Less common	Less common	Hypoparathyroidism Candidiasis Hypogonadism
APS type 2	+	+	+	Hypogonadism Malabsorption
APS type 3	-	+	+	Malabsorption
Thymoma	+	-	+	Myasthenia gravis Cushing syndrome
Chromosomal abnormalities (Turner syndrome, Down's syndrome)	-	+	+	Cardiac dysfunction
Kearns–Sayre syndrome	-	+	-	Myopathy Hypoparathyroidism Hypogonadism
Wolfram syndrome	-	+	-	Diabetes insipidus Optic atrophy Deafness
POEMS syndrome	-	+	-	Polyneuropathy Hypogonadism Plasma cell dyscrasias