Sarcoma and Hemangioendothelioma

Question 1

What is the definition of a pulmonary artery sarcoma?

Answer 1

• Malignant mesenchymal tumor arising from the intima/wall of the pulmonary trunk

Question 2

What is the epidemiology of pulmonary artery sarcomas?

Answer 2

• Rare tumors, represent <1% of all malignant mesenchymal tumors of the lung
• usually occur in adults
• No gender predilection
• often confused for other conditions:
  
  • pulmonary HTN, pneumonia, or asthma

Question 3

What are the microscopic findings associated with pulmonary artery sarcoma?

Answer 3

• tumor obliterating the lumen of artery
  
  • IMP: MUST identify the vessel that the tumor is arising from
• arising from pulmonary trunk
• polypoid tumor in an intraluminal location
• may be up to 5 cm in size

Question 4

What histologic features can be identified in pulmonary artery sarcomas?

Answer 4

• Varied mesenchymal differentiation can be seen:
  
  • Angiosarcoma
  • Rhabdomyosarcoma
  • Chondrosarcoma
  • Osteosarcoma
  • Leiomyosarcoma

**predominantly see spindled cells

IMP: oftentimes a differentiation cannot be achieved

Question 5

What is the definition of epithelioid hemangioendothelioma?

Answer 5

• vascular neoplasm of intermediate malignant potential
• vascular origin from precursor mesenchymal cells

Question 6

What is the location of epithelioid hemangioendotheliomas?

Answer 6

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• can be anterior or posterior mediastinum
• rare tumor of the lung and is more common in young adults with more female predilection
• usually will see bilateral pulmonary infiltrates

Question 7

What are macroscopic features of epithelioid hemangioendothelioma?

Answer 7

• multiple pulmonary nodules with nodules in different phases of development
• nodules can be soft or mucoid in consistency
• can measure 2-3 cm

Question 8

What is the histologic patterns seen in epithelioid hemangioendothelioma?

Answer 8

• multiple pulmonary nodules
• nodules in different phases of development
• prominent chondromyxoid backgroud OR hyalinization
• epithelioid cells are embedded in the myxoid or hyalinized background
• LOW mitotic count - IMP
• signet ring cell-like cellular appearance
• cluster of tumor cells in polypoid intraalveolar patterns
• **extravasated red cells***

Question 9

What is the definition of ciliated muconodular papillary tumor?

Answer 9

• Benign peripheral lung nodule composed of ciliated columnar cells, mucous cells and basal cell proliferation
• Shown to have BRAF-V600E driver mutations and AKT1 mutations

Question 10

What is the clinical presentation of ciliated muconodular papillary tumor?

Answer 10

• small, peripheral lung nodule 1 cm in average diameter
• mostly asymptomatic and discovered on routine imaging
• mostly seen in middle-aged to older adults
• indolent behavior with good prognosis

Question 11

What are the histologic features of ciliated muconodular papillary tumor?

Answer 11

• Glandular or papillary proliferation of epithelial cells showing admixture of ciliated columnar cell, mucous cells and basal cells
• periphery of lesions contains copious amounts of inspissated mucous filling alveoli
• tumors are penetrated by bronchovascular bundles or medium-sized muscular arteries
• mucin may infiltrate adjacent parenchyma suggestive of an infiltrative process

Question 12

What are the cytological features of ciliated muconodular papillary tumor?

Answer 12

• ciliated columnar cells line surface of glandular and papillary structures
• continuous layer of basal cells in outer layer of glands/papillae
• mucous cells are seen interspersed with other elements
• Must have complete absence of cytologic atypia, nuclear pleomorphism, mitotic activity, or necrosis

Question 13

What are the immunohistochemical staining patterns of ciliated muconodular papillary tumor?

Answer 13

• p40/p63 highlights the basal cells
• ciliated cells focally positive for MUC5AC
• rare chromogranin/synaptophysin positive cells admixed with basal cells