Quiz-summary
0 of 1 questions completed
Questions:
- 1
Information
Presented by William Westra, M.D. and prepared by Walter Klein, M.D.
Case 4: 63 year-old man with a pleural-based lung mass.
You have already completed the quiz before. Hence you can not start it again.
Quiz is loading...
You must sign in or sign up to start the quiz.
You have to finish following quiz, to start this quiz:
Results
Time has elapsed
Categories
- Not categorized 0%
- 1
- Answered
- Review
-
Question 1 of 1
1. Question
Week 162: Case 4
63 year-old man with a pleural-based lung mass./images/klein/111703case4fig1.jpg
/images/klein/111703case4fig2.jpg
/images/klein/111703case4fig3.jpg
/images/klein/111703case4fig4.jpg
/images/klein/111703case4fig5.jpgCorrect
Answer: Solitary fibrous tumor
Histology: The tumor is characterized by the proliferation of spindled cells within a fibrocollagenous background. The proliferation is somewhat haphazard (i.e. patternless). The cellularity is variable as collagen rich hypocellular zones alternate with collagen poor hypercellular zones. The individual tumor cells are separated by a lace-like deposition of intercellular collagen. The vasculature is notable for gaping stag horn-like vessels. The tumor cells are very uniform without significant atypia, and the mitotic rate is very low. An immunohistochemical stain for CD34 is strongly and diffusely positive.
Discussion: In 1931 Klemperer and Rabin described a distinctive neoplasm arising in the pleura which they named “localized tumor of the pleura”. Since that first description, there has been considerable confusion regarding the nature of these tumors. Some still refer to them as “solitary fibrous mesotheliomas”, reflecting a persistent yet erroneous perception that they are derived from mesothelial cells and represent a localized variant of mesothelioma. While it is true that that solitary fibrous tumors (SFTs) often arise in the pleura, they differ from mesotheliomas in several important respects:
1) SFTs are not associated with exposure to aesbestos;
2) SFTs usually behave in a non-aggressive fashion; and
3) SFTs demonstrate different immunohistochemical and ultrastructural characteristics relative to mesotheliomas.In contrast to mesotheliomas, SFTs are not immunoreactive for cytokeratin or calretinin, and they are consistently immunoreactive for CD34. Recognition of its non-mesothelial origin has undermined the notion that SFT is limited to the chest cavity and other mesothelial-lined sites. As a result, there has been a recent explosion of reports describing SFT in previously unrecognized sites.
Distinguishing SFTs from other spindle cell processes can be difficult. Due to the variability of its light microscopic appearance, SFT morphologically overlaps with a spectrum of other tumor types, giving rise to a formidable differential diagnosis. Hemangiopericytoma-like vascularity, storiform and “herring bone” formations, and neural-type palisades are just a few histologic patterns that may be developed in SFTs and cause confusion with other tumor types. Accordingly, the differential diagnosis of SFT, regardless of tumor site, routinely encompasses hemangiopericytoma, malignant fibrohistiocytoma, fibrosarcoma, leiomyosarcoma, and benign and malignant nerve sheath tumors. Despite the variability of its histologic appearance, the diagnosis of SFT can generally be established by routine light microscopy. Importantly, it is the combination of these variable histologic patterns that is most helpful in distinguishing SFT from the spectrum of neoplasms it mimics. If difficulties persist, an appropriate panel of immunohistochemical markers that includes CD34 is usually helpful in confirming the diagnosis. SFTs are consistently immunoreactive for CD34 whereas most other entities that commonly enter the differential diagnosis are uniformly CD34 negative.
10% to 20% of SFTs arising in the pleura behave in an aggressive fashion. Features of malignancy include dense cellularity, cellular anaplasia, and a high mitotic rate (4 or more mitoses per 10 high power fields). Importantly, tumor resectability has been suggested as the single most important determinant of clinical outcome for those tumors involving the pleura.
Incorrect
Answer: Solitary fibrous tumor
Histology: The tumor is characterized by the proliferation of spindled cells within a fibrocollagenous background. The proliferation is somewhat haphazard (i.e. patternless). The cellularity is variable as collagen rich hypocellular zones alternate with collagen poor hypercellular zones. The individual tumor cells are separated by a lace-like deposition of intercellular collagen. The vasculature is notable for gaping stag horn-like vessels. The tumor cells are very uniform without significant atypia, and the mitotic rate is very low. An immunohistochemical stain for CD34 is strongly and diffusely positive.
Discussion: In 1931 Klemperer and Rabin described a distinctive neoplasm arising in the pleura which they named “localized tumor of the pleura”. Since that first description, there has been considerable confusion regarding the nature of these tumors. Some still refer to them as “solitary fibrous mesotheliomas”, reflecting a persistent yet erroneous perception that they are derived from mesothelial cells and represent a localized variant of mesothelioma. While it is true that that solitary fibrous tumors (SFTs) often arise in the pleura, they differ from mesotheliomas in several important respects:
1) SFTs are not associated with exposure to aesbestos;
2) SFTs usually behave in a non-aggressive fashion; and
3) SFTs demonstrate different immunohistochemical and ultrastructural characteristics relative to mesotheliomas.In contrast to mesotheliomas, SFTs are not immunoreactive for cytokeratin or calretinin, and they are consistently immunoreactive for CD34. Recognition of its non-mesothelial origin has undermined the notion that SFT is limited to the chest cavity and other mesothelial-lined sites. As a result, there has been a recent explosion of reports describing SFT in previously unrecognized sites.
Distinguishing SFTs from other spindle cell processes can be difficult. Due to the variability of its light microscopic appearance, SFT morphologically overlaps with a spectrum of other tumor types, giving rise to a formidable differential diagnosis. Hemangiopericytoma-like vascularity, storiform and “herring bone” formations, and neural-type palisades are just a few histologic patterns that may be developed in SFTs and cause confusion with other tumor types. Accordingly, the differential diagnosis of SFT, regardless of tumor site, routinely encompasses hemangiopericytoma, malignant fibrohistiocytoma, fibrosarcoma, leiomyosarcoma, and benign and malignant nerve sheath tumors. Despite the variability of its histologic appearance, the diagnosis of SFT can generally be established by routine light microscopy. Importantly, it is the combination of these variable histologic patterns that is most helpful in distinguishing SFT from the spectrum of neoplasms it mimics. If difficulties persist, an appropriate panel of immunohistochemical markers that includes CD34 is usually helpful in confirming the diagnosis. SFTs are consistently immunoreactive for CD34 whereas most other entities that commonly enter the differential diagnosis are uniformly CD34 negative.
10% to 20% of SFTs arising in the pleura behave in an aggressive fashion. Features of malignancy include dense cellularity, cellular anaplasia, and a high mitotic rate (4 or more mitoses per 10 high power fields). Importantly, tumor resectability has been suggested as the single most important determinant of clinical outcome for those tumors involving the pleura.