Thymic carcinoma pathophysiology: Difference between revisions
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==Microscopic Pathology== | ==Microscopic Pathology== | ||
Cytologically malignant - variable morphology | *Cytologically malignant - variable morphology | ||
Squamous cell carcinoma is the most common (65-73% of cases) | *Squamous cell carcinoma is the most common (65-73% of cases) | ||
+/-Squamous differentiation | *+/-Squamous differentiation | ||
==Associated Conditions== | ==Associated Conditions== | ||
Revision as of 15:04, 22 December 2015
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Thymic Carcinoma Microchapters |
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Diagnosis |
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Case Studies |
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Thymic carcinoma pathophysiology On the Web |
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American Roentgen Ray Society Images of Thymic carcinoma pathophysiology |
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Risk calculators and risk factors for Thymic carcinoma pathophysiology |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Alejandro Lemor, M.D. [2]Parminder Dhingra, M.D. [3]
Overview
Pathophysiology
The thymic carcinoma is a tumor of the thymic epithelium, but it is associated with lack of immature lymphocytes and often presents with more invasive or metastatic disease.[1]
Genetics
Thymic carcinoma, specially the squamous cell subtype, is associated with genetic alterations. It has been reported chromosomal gains like +1q, +17q, +18 and chromosomal losses of -3p, -6, -13q,-16q, -17p to a relation with this subtype. [2]
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Patologic Classification
Thymic carcinomas are categorized in low and high grade histological subtypes, which includes squamous cell carcinoma, basaloid carcinoma, mucoepidermoid carcinoma, lymphoepithelioma-like carcinoma, sarcomatoid carcinoma (carcinosarcoma), clear cell carcinoma, papillary adenocarcinoma, carcinoma with t(15;19) translocation, neuroendrocrine carcinomas, undifferentiated carcinoma and combined thymic epithelial tumors.[3]
- Squamous cell carcinoma: This subtype of thymic carcinoma is the most common and exhibits atypia with a clear-cut aspect of keratinization with keratin pearls as seen in squamous cell carcinomas. Squamous cell carcinoma lack of capsule and presents with necrosis and hemorrhage.
- Basaloid carcinoma: This subtype consists of solid lobules of tumor cells with marginal palisading, without keratinization and a basophilic pattern due to an elevated nucleocytoplasmic ratio.
- Mucoepidermoid carcinoma: The characteristic features for this rare subtype is the presence of squamous and mucus producing cells, with moderate atypia. It has a mucinous macroscopic appearance.
- Lymphoepithelioma-like carcinoma: The morphology of this subtype resembles the nasopharingeal lymphoepitelioma, with syncytial growth of undifferentiated malignant cells.
- Sarcomatoid carcinoma (carcinosarcoma): It is also known as spindle cell thymic carcinoma, is an infiltrative neoplasm with large areas of coagulative necrosis and without a capsule. It is an uncommon tumor that affects patients between 40-80 years old.
- Clear cell carcinoma: Consist of cells with minimal nuclear atypia with a characteristic lucent cytoplasm and a lobulated architecture without sinusoidal vasculature (in contrast with the renal clear cell carcinoma)
- Papillary adenocarcinoma: It has a tubulopapillary pattern growth with cuboidal cells and Psammoma bodies may be present. Type A thymoma may be the origin of this subtype of carcinoma due an expression of malignant transformation.
- Carcinoma with t(15;19) translocation: It is an aggressive tumor with a translocation t(15;19)(q13:p13.1 )that has the characteristic presence of undifferentiated cells with high mitotic activity and squamous morphology.
- Neuroendocrine Carcinomas: The neuroendocrine thymic carcinomas are classified in 4 categories: typical, atypical, small cell and large cell carcinomas. The typical and atypical are categorized as well differentiated neuroendocrine carcinomas, and the small cell and large cell carcinomas are categorized as poorly differentiated.
Classification of Neuroendocrine Carcinomas[4]
| Well Differentiated | Poorly Differentiated | ||
|---|---|---|---|
| Typical Carcinoid | Atypical Carcinoid | Small Cell | Large Cell |
| No necrosis; <2 mitoses per 2 mm2 (10 HPF) |
Necrosis present and/or 2-10 mitoses per 2 mm2 (10 HPF) |
Small cell cytology | Non-small cell NEC with >10 mitoses per 2 mm2 (10 HPF) |
| Morphological Variants Spindle cell type Pigmented type With amyloid (extrathyroidal medullary carcinoma) Oncocytic/oxyphilic type Mucinous Angiomatoid type Combinations of the above variants |
Variants SCNEC combined with Non-NECs |
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HPF: High power field, SCNEC: Small cell neuroendocrine carcinoma, NEC: Neuroendocrine carcinoma
Microscopic Pathology
- Cytologically malignant - variable morphology
- Squamous cell carcinoma is the most common (65-73% of cases)
- +/-Squamous differentiation
Associated Conditions
Thymic carcinoma has not been reported in association with myasthenia gravis, in contrast with thymoma. Paraneoplasic syndromes had been reported in the neuroendocrine subtype, but is not as common as in thymomas.
References
- ↑ Thomas CR, Wright CD, Loehrer PJ (1999). "Thymoma: state of the art". Journal of Clinical Oncology : Official Journal of the American Society of Clinical Oncology. 17 (7): 2280–9. PMID 10561285. Retrieved 2012-01-18. Unknown parameter
|month=ignored (help) - ↑ "http://www.iarc.fr/en/publications/pdfs-online/pat-gen/bb10/BB10.pdf" (PDF). External link in
|title=(help) - ↑ Suster, S.; Rosai, J. (1991). "Thymic carcinoma. A clinicopathologic study of 60 cases". Cancer. 67 (4): 1025–32. PMID 1991250. Unknown parameter
|month=ignored (help) - ↑ "http://www.iarc.fr/en/publications/pdfs-online/pat-gen/bb10/BB10.pdf" (PDF). External link in
|title=(help)