Template:Vessels, soft tissue

Arteries

Author: Mikael Häggström

Presentations

• 

  Aneurysm

• Thrombus

Gross processing

A minimal gross processing of arteries includes a longitudinal dissection and inspection of tunica intima.

Consecutive cross-sections allows for a detection and estimation of atherosclerotic stenosis.

Plaque at different degrees of atherosclerotic stenosis.

Microscopic examination

• Confirm that it is actually an artery (may be a vein, and a neuron may look grossly like a small artery).
• Look for atherosclerosis and thrombosis.
• Classify atherosclerosis as mild, moderate or severe.
• If cross-sections were made, estimate the maximum percentage of occlusion for each artery.

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  Histopathology of pre-atherosclerotic intimal lesions: Intimal thickening (A) consists mainly of smooth muscle cells in a proteoglycan-rich matrix. Intimal xanthoma (B) displays intimal thickening with isolated foam cells (arrows).

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  A progressive atherosclerotic lesion: Pathological intima thickening (A) has some extracellular lipid (EL) present deep in the lesion without true necrosis.

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  Progressive lesion: A fibrous cap atheroma has a well-formed necrotic core (NC) containing lipids with an overlying thick fibrous cap (FC).

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  Progressive lesion: Fibrocalcific plaques are heavily calcified lesions with or without a necrotic core.

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  Histopathology of plaque components in atherosclerosis: (A) Intraplaque neovasculature (arrows); (B) intraplaque hemorrhage; (C) large areas of calcification seen as purple morula; (D) lumen thrombus (arrowhead); stained with hematoxylin and eosin (H&E); (E) macrophage infiltration; stained with CD68 antibodies.

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  Cross-sections collapse more or less after cutting, and estimations of the maximum percentage of stenosis should be made as imagined on an expanded blood vessel, as: 1-(lumen area)/(atherosclerosis area). In this case, there is 45-50% stenosis.

Evaluate for giant cell arteritis at least upon request. It is characterized by a granulomatous inflammation of arteries with discontinuous and fragmented internal elastic lamina.

Microscopy report

• Classify any atherosclerosis as mild, moderate or severe.
• If cross-sections were made, state the maximum percentage of stenosis for each artery.

Example:

Sections of the three main coronary arteries reveal << mild / moderate / severe>> atherosclerosis, with approximately __%, __% and __% stenosis of the left anterior descending, left circumflex coronary artery and right coronary artery, respectively.

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Thrombus

Author: Mikael Häggström

Composition of a fresh thrombus.

Microscopic evaluation

An organizing thrombus.

Look for presence of fibroblasts or myofibroblasts, conferring a diagnosis of an organizing thrombus.

Reporting

Example:

Right profunda femoris artery clot, excision: Organizing thrombus.

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Aneurysm

Author: Mikael Häggström

Cross-section of an arterial aneurysm, showing most of the area consisting of organized mural thrombus (tan-brown area).

Gross processing

• Describe the shape (generally either fusiform or saccular).
• Measure the length and diameter

Make several cross-sections and look for any dissection in the wall.

Gross report

On this resource, the following formatting is used for comprehensiveness:

• Minimal depth
• (Moderate depth)
• ((Comprehensive))

(( A. Labeled -left upper extremity aneurysm. The specimen is received in formalin and consists of a segment of)) fusiformly dilated vessel measuring 11.5 cm in length and the diameter is 6.5 (x 6.5 cm). Upon sectioning, <<most \ (( __ %))>> of the area is occupied by tan-yellow to tan-red non-homogenous surface, consistent with an organized mural thrombus. (No visible wall dissection.)

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Tophus/gout

Author: Mikael Häggström

Preparation

A tophus specimen should be sent dry to the pathology department, and not be put in formalin.

Gross processing

A large tophus.

Preferably make a touch prep for polarized light microscopy. At least if urate crystals are not initially detected, take sections to be put in 100% alcohol and tell the histology lab to prepare it as per gout protocol. With characteristic crystals on a touch prep, sections may possibly be submitted in formalin.

Microscopy evaluation

On a touch prep, look for needle-shaped crystals of urate. On polarized light, these will have negative birefriengence.

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  Light microscopy of a touch preparation of a gout tophus, showing needle-shaped crystals

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  Uric acid crystals in polarized light, showing negative birefringence, with yellow color when aligned parallel to the axis of the red compensator, and blue when aligned perpendicularly to it.

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  In contrast, pseudogout, also called calcium pyrophosphate dihydrate (CPPD) crystal deposition disease) displays rhombus-shaped or parallelogram-shaped crystals with negative birefringence.

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  To look for crystals in a regular light microscope, look without condenser (right image) if possible, wherein crystal outlines are more clear than with condenser (left image). CPPD crystals are depicted.

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Soft tissue tumor

Author: Mikael Häggström

Gross processing

• 

  If it appears fatty, gross and evaluate as a lipomatous tumor.

Generally sample one slice per centimeter.

Evaluation

A solitary fibrous tumor, an example of spindle cell tumor.

In case of spindle cell tumors (having elongated nuclei), the following features may help to roughly classify the tumor:

• Pointed on both ends: True fibroblastic tumors
• Pointed on one end and blunted on the other ("bullet-shaped"): Neural/nerve sheath tumors (see section below)
• Blunted on both ends ("cigar-shaped"): Smooth muscle tumor
• Triangular: Myofibroblastic

In uncertain cases, the following immunohistochemistry markers are usually helpful:

• CD34, indicating a solitary fibrous tumor
• S100, indicating a neural or nerve sheath tumor (see section below)
• Desmin, indicating a muscular tumor (skeletal muscle or Smooth muscle tumor, latter also positive on SMA)
• Beta catenin, indicating fibromatosis

At least in case of enlarged atypical nuclei, consider sarcoma as a differential diagnosis, and if unsure, have a low threshold for consulting with people with expertise in the matter, as the visual difference between benign and malignant spindle cells is relatively subtle. Relevant stains may include MDM2 and CDK4 for liposarcoma, as well as desmin and SMA for Leiomyosarcoma.

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  Main features of liposarcoma:
  - Spindle cells with enlarged, hyperchromatic nuclei.
  - Apparently univacuolated adipocytes (may look normal).
  - Lipoblasts (multivacuolated), but neither necessary nor sufficient for diagnosis.

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  Leiomyosarcoma: Variable atypia, often with cytoplasmic vacuoles at both ends of nuclei, and frequent mitoses.

Neural or nerve sheath tumors

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  Schwannoma, characterized by cellular Antoni A areas (top) and a loose paucicellular Antoni B areas (bottom).

• 

  Schwannoma is also characterized by Verocay bodies (one encircled), which are stripes of anuclear zones, separated by cellular palisades.

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  Neurofibroma: A spindle cell lesion composed of slender fibroblast-like cells with storiform pattern and very low amount of stroma.

• 

  In case of atypia, keep in mind that metastatic melanoma is generally also positive for S100.

Further information: Evaluation of suspected malignancies

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Peripheral nerve sheath tumor

1. REDIRECT Soft tissue tumor

Lipomatous tumor

Author: Mikael Häggström

Lipomatous tumor.

Fixation

Generally 10% neutral buffered formalin.

  See also: General notes on fixation

Comprehensiveness

On this resource, the following formatting is used for comprehensiveness:

• Minimal depth
• (Moderate depth)
• ((Comprehensive))

Gross processing

• Perform consecutive slicing of the entire specimen.
• Look for signs of liposarcoma: Mainly by firm volumes. Color varies from yellow to white (and firm) depending on the proportion of adipocytic, fibrous and/or myxoid content. Areas of fat necrosis are common in larger lesions. Rarely, infiltrative growth is seen.
• Submit slices from any suspicious parts, or at least one representative slice from the specimen. (A more comprehensive practice is to submit 1 section per centimeter, and 2 sections per cassette.)

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  Cross-section of lipoma. Homogenous texture.

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  Liposarcoma: Tumor section reveals brownish-yellowish areas, hemorrhagic and calcific zones.

Gross report

• Color
• Even absence of hemorrhage or necrosis.

Example:

Mass ((weighing 121 grams)) and measuring 10 x 6,5 x 3,5 cm. ((The surgical margin is intact.)) Cut sections show homogenous yellow color, with no hemorrhage or necrosis. ((The specimen is serially sectioned, and representative sections are submitted for microscopic examination in __ cassettes.))

  See also: General notes on gross processing

Microscopic evaluation

• 

  Lipoma: lobules of mature white adipose tissue divided by delicate and inconspicuous fibrous septa containing thin-walled capillary-sized vessels. Still, look close at the fibrous septa:

• 

  An atypical lipomatous tumor (also termed well-differentiated liposarcoma), lipoma-like subtype. At low magnification, the majority of the tumor essentially has the look of benign mature adipocytes (except for mildly increased variation in lipid droplet sizes), but high magnification of a fibrous band shows spindle cells with enlarged, hyperchromatic nuclei. Another clue for liposarcoma is a higher variability of lipid droplet sizes.

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  Fibrolipoma is a lipoma with focal areas of large amounts of fibrous tissue.
  A sclerotic lipoma is one step further: a predominantly fibrous lesion with focal areas of fat.
  If unsure of degree of fibrosis: Simply report as lipoma.

• 

  Angiolipoma is a lipoma with abundant capillaries, with hyaline or fibrin (pictured) thrombi.

• 

  Main features of liposarcoma:
  - Spindle cells with enlarged, hyperchromatic nuclei.
  - Apparently univacuolated adipocytes (may look normal).
  - Lipoblasts, but is neither necessary nor sufficient for diagnosis.

• 

  Lipoblast features

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  Myxoid liposarcoma: Hypercellular solid sheets of cells lying back to back, with round cells or primitive cytomorphology.

A pedunculated lipomatous skin tumor may be a pedunculated lipofibroma:

• 

  Pedunculated lipofibroma, gross pathology

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  Histopathology, showing thin rim of epidermis, and dermal lipocytes without capsule.

Microscopy/Histopathology report

For lipomas: (Absence of signs of malignancy.)

(Chest wall, left lateral, excision:) Lipoma. (Negative for malignancy) ((Microscopic description: Tissue composed of univacuolar fat cells and delicate and inconspicuous fibrous septa.))

  See also: General notes on reporting

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Hernia sac

Author: Mikael Häggström

Gross pathology of a hernia sac.

Comprehensiveness

On this resource, the following formatting is used for comprehensiveness:

• Minimal depth
• (Moderate depth)
• ((Comprehensive))

Fixation

Generally 10% neutral buffered formalin.

Gross processing

A gross inspection is almost always enough, and tissue generally does not need to be submitted except in unique circumstances. ((Still you may submit 1 cassette of one or more representative sections for an inguinal hernia sac in a patient aged up to 16 years of age, or in case of hernia sacs from other regions than inguinal.))

Gross report

((A. Labeled - ___. The specimen is received in formalin and consists of)) __ fragment(s) of pink-tan fibromembranous tissue, measuring ___ cm in greatest dimension and ___ cm in greatest thickness. The surfaces are smooth. There are no sections submitted for microscopic examination. (Representative sections are submitted for microscopic examination in __ cassettes.)

Microscopic report

Mesothelial lining of a hernia sac.

In case of a gross only examination, the microscopic report may still be given as a formality:

Right inguinal region, herniorrhaphy: Hernia sac, gross examination only.

When microscopy slides of the case are available, you may screen the sample at low magnification to rule out obvious pathology:

Umbilical hernia sac, hernia repair: Connective tissue lined by mesothelium, consistent with hernia sac.

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