Thymoma diagnostic study of choice

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Shyam Patel [2] Associate Editor(s)-in-Chief: Khuram Nouman, M.D. [2]

Overview

Thymoma can be largely diagnosed by using radiological techniques.

Diagnostic Study of Choice

Study of Choice

Posterior–anterior (PA) and lateral x-ray of the chest are helpful in diagnosing most of the thymomas.

Among the patients who present with clinical signs of myasthenia gravis (MG), CT scan is the test of choice for the diagnosis of thymoma.
CT scan with IV contrast and MRI are helpful in determining the vascularity of the thymoma and helps in safe surgical removal of large tumors.
PET scan is very valuable in diagnosing the cases of invasive malignant thymoma.^[1]
Thallium 201 single photon emission computed tomography is useful to distinguish normal thymic tissue from hyperplastic tissue or thymoma
Ultrasonically guided core needle biopsy is used to obtain larger tissue specimens for histological examination.
Annessi and colleagues were able to diagnose thymoma in all patients who had undergone anterior mediastinal core needle biopsy by ultrasonic guidance with a sensitivity and specificity of 100%.

Staging

The thymic epithelial tumor staging system was initially proposed by Bergh and his colleagues in 1978, modified by Wilkins and Castleman in 1979, and further developed by Masaoka et al. in 1981.^[2]^[3]^[4]^[5]
Modified Masaoka staging grouped with TNM classification is the most widely adopted system for thymic epithelial tumors currently in use.

Modified Masaoka Clinical Staging of Thymoma

**Modified Masaoka Clinical Staging of Thymoma (1994)**^[6]
Stage	Description
I	Macroscopically and microscopically completely encapsulated
II	A: Microscopic transcapsular invasion B: Macroscopic invasion into surrounding fatty tissue or grossly adherent to but not through mediastinal pleura or pericardium
III	Macroscopic invasion into neighboring organs (pericardium, great vessels, lung) A: Without invasion of great vessels B: With invasion of great vessels
IV	A: Pleural or pericardial dissemination B: Lymphogenous or hematogenous metastasis

TNM Classification of Thymic Epithelial Tumors

**TNM Classification of Thymic Epithelial Tumors by Yamakawa and Masaoka (1991)**^[7]
T/N/M Stage		Description
T	T1	Macroscopically completely encapsulated and microscopically no capsular invasion
	T2	Macroscopic adhesion or invasion into surrounding fatty tissue or mediastinal pleura, or microscopic invasion into the capsule
	T3	Invasion into neighboring organs, such as pericardium, great vessels, and lung
	T4	Pleural or pericardial dissemination
N	N0	No lymph node metastasis
	N1	Metastasis to the anterior mediastinal lymph nodes
	N2	Metastasis to the intrathoracic lymph nodes except anterior mediastinal lymph nodes
	N3	Metastasis to extrathoracic lymph nodes
M	M0	No hematogenous metastasis
	M1	Hematogenous metastasis

**Combined Masaoka Staging/TNM Classification (1994)**^[8]
Masaoka Stage	T	N	M
Stage I	T1	N0	M0
Stage II	T2	N0	M0
Stage III	T3	N0	M0
Stage IVa	T4	N0	M0
Stage IVb	Any T	N1, N2, or N3	M0
Stage IVb	Any T	Any N	M1

Previously Reported Staging System

**Masaoka Staging (1981)**^[4]
Stage	Description
I	Macroscopically completely encapsulated and microscopically no capsular invasion
II	1. Macroscopic invasion into the surrounding fatty tissue or mediastinal pleura 2. Microscopic invasion into the capsule
III	Macroscopic invasion into the neighboring organs (pericardium, great vessels, or lung)
IVa	Pleural or pericardial dissemination
IVb	Lymphogenous or hematogenous metastasis

**Clinical Staging by Bergh (1978) and Wilkins (1979)**^[3]^[2]
Author	Stage	Description
Bergh et al.	I	Intact capsule or growth within the capsule
	II	Pericapsular growth into the mediastinal fat tissue
	III	Invasive growth into the surrounding organs and/or intrathoracic metastases
Wilkins et al.	I	Intact capsule or growth within the capsule
	II	Pericapsular growth into the mediastinal fat tissue or adjacent pleura or pericardium
	III	Invasive growth into the surrounding organs and/or intrathoracic metastases

References

↑ Scagliori E, Evangelista L, Panunzio A, Calabrese F, Nannini N, Polverosi R; et al. (2015). “Conflicting or complementary role of computed tomography (CT) and positron emission tomography (PET)/CT in the assessment of thymic cancer and thymoma: our experience and literature review”. Thorac Cancer. 6 (4): 433–42. doi:10.1111/1759-7714.12197. PMC 4511321. PMID 26273398.
↑ ^2.0 ^2.1 Wilkins, EW.; Castleman, B. (1979). “Thymoma: a continuing survey at the Massachusetts General Hospital”. Ann Thorac Surg. 28 (3): 252–6. PMID 485626. Unknown parameter |month= ignored (help)
↑ ^3.0 ^3.1 Bergh, NP.; Gatzinsky, P.; Larsson, S.; Lundin, P.; Ridell, B. (1978). “Tumors of the thymus and thymic region: I. Clinicopathological studies on thymomas”. Ann Thorac Surg. 25 (2): 91–8. PMID 626543. Unknown parameter |month= ignored (help)
↑ ^4.0 ^4.1 Masaoka, A.; Monden, Y.; Nakahara, K.; Tanioka, T. (1981). “Follow-up study of thymomas with special reference to their clinical stages”. Cancer. 48 (11): 2485–92. PMID 7296496. Unknown parameter |month= ignored (help)
↑ Kondo, K. (2005). “Invited commentary”. Ann Thorac Surg. 80 (6): 2000–1. doi:10.1016/j.athoracsur.2005.08.053. PMID 16305832. Unknown parameter |month= ignored (help)
↑ Masaoka, A.; Yamakawa, Y.; Niwa, H.; Fukai, I.; Saito, Y.; Tokudome, S.; Nakahara, K.; Fujii, Y. (1994). “Thymectomy and malignancy”. Eur J Cardiothorac Surg. 8 (5): 251–3. PMID 8043287.
↑ Sinha Hikim AP, Hoffer AP (1987). “Quantitative analysis of germ cells and Leydig cells in rat made infertile with gossypol”. Contraception. 35 (4): 395–408. PMID 3621939.
↑ Tsuchiya R, Koga K, Matsuno Y, Mukai K, Shimosato Y (1994). “Thymic carcinoma: proposal for pathological TNM and staging”. Pathol Int. 44 (7): 505–12. PMID 7921194.

[pmid26273398-1] Scagliori E, Evangelista L, Panunzio A, Calabrese F, Nannini N, Polverosi R; et al. (2015). “Conflicting or complementary role of computed tomography (CT) and positron emission tomography (PET)/CT in the assessment of thymic cancer and thymoma: our experience and literature review”. Thorac Cancer. 6 (4): 433–42. doi:10.1111/1759-7714.12197. PMC 4511321. PMID 26273398.

[Wilkins-1979-2] 2.0 ^2.1 Wilkins, EW.; Castleman, B. (1979). “Thymoma: a continuing survey at the Massachusetts General Hospital”. Ann Thorac Surg. 28 (3): 252–6. PMID 485626. Unknown parameter |month= ignored (help)

[Bergh-1978-3] 3.0 ^3.1 Bergh, NP.; Gatzinsky, P.; Larsson, S.; Lundin, P.; Ridell, B. (1978). “Tumors of the thymus and thymic region: I. Clinicopathological studies on thymomas”. Ann Thorac Surg. 25 (2): 91–8. PMID 626543. Unknown parameter |month= ignored (help)

[Masaoka-1981-4] 4.0 ^4.1 Masaoka, A.; Monden, Y.; Nakahara, K.; Tanioka, T. (1981). “Follow-up study of thymomas with special reference to their clinical stages”. Cancer. 48 (11): 2485–92. PMID 7296496. Unknown parameter |month= ignored (help)

[Kondo-2005-5] Kondo, K. (2005). “Invited commentary”. Ann Thorac Surg. 80 (6): 2000–1. doi:10.1016/j.athoracsur.2005.08.053. PMID 16305832. Unknown parameter |month= ignored (help)

[Masaoka-1994-6] Masaoka, A.; Yamakawa, Y.; Niwa, H.; Fukai, I.; Saito, Y.; Tokudome, S.; Nakahara, K.; Fujii, Y. (1994). “Thymectomy and malignancy”. Eur J Cardiothorac Surg. 8 (5): 251–3. PMID 8043287.

[pmid3621939-7] Sinha Hikim AP, Hoffer AP (1987). “Quantitative analysis of germ cells and Leydig cells in rat made infertile with gossypol”. Contraception. 35 (4): 395–408. PMID 3621939.

[pmid7921194-8] Tsuchiya R, Koga K, Matsuno Y, Mukai K, Shimosato Y (1994). “Thymic carcinoma: proposal for pathological TNM and staging”. Pathol Int. 44 (7): 505–12. PMID 7921194.

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