Part 2

If synovial fluid is aspirated from a patient with gout, the fluid can be examined for the presence of sodium urate crystals, which are seen here to be needle shaped. If they are observed under polarized light with a red compensator, they appear yellow (negatively birefringent) in the main ("slow") axis of the compensator and blue in the opposite perpendicular direction.

The pale areas seen here are tophi, or aggregates of urate crystals surrounded by infiltrates of lymphocytes, macrophages, and foreign body giant cells. A tophus is the characteristic finding of gout. Tophi are most likely to be found in soft tissues, including tendons and ligaments, around joints. Less commonly tophi appear elsewhere. Tophaceous gout results from continued precipitation of sodium urate crystals during attacks of acute gout.

This is the synovium in rheumatoid arthritis. There is chronic inflammation with lymphocytes and plasma cells that produce the blue areas beneath the nodular proliferations. This "pannus" is destructive and produces erosion of the articular cartilage, eventually destroying the joint.

Here is a rheumatoid nodule. Such nodules are seen in patients with severe rheumatoid arthritis and appear beneath the skin over bony prominences such as the elbow. They can occasionally appear in visceral organs. There is a central area of fibrinoid necrosis surrounded by pallisading epithelioid macrophages. and other mononuclear cells.

normal parathyroid gland for comparison. Adipose tissue cells are mixed with the parathyroid tissue. The amount of fat varies somewhat.

Here is a parathyroid adenoma, which is the most common cause for primary hyperparathyroidism. A rim of normal parathyroid tissue admixed with adipose

tissue cells is seen compressed to the right and lower edge of the adenoma.

In parathyroid hyperplasia, there is little or no adipose tissue, but any or all cell types normally found in parathyroid are present. Note the pink oxyphil cells here. This is actually "secondary hyperparathyroidism" with enlarged glands as a consequence of chronic renal failure with impaired phosphate excretion. The increased serum phosphate tends to drive serum calcium down, which in turn drives the parathyroids to secrete more parathormone.

This is a parathyroid carcinoma seen at medium power on the left and higher power on the right. The nests of neoplastic cells that are not very pleomorphic.

Note the bands of fibrous tissue between the nests. Parathyroid carcinomas infiltrate surrounding structures in the neck.

Follicular neoplasm (a follicular adenoma histologically) that is surrounded by a thin white capsule.

Normal thyroid follicles appear at the lower right. The follicular adenoma is at the center to upper left. This adenoma is a well- differentiated neoplasm because it closely resemble normal tissue. The follicles of the adenoma contain colloid, but there is greater variability in size than normal.

Well-differentiated follicles resemble normal thyroid parenchyma

Sectioning through a lobe of excised thyroid gland reveals papillary carcinoma. This neoplasm can be multifocal, as seen here, because of the propensity to invade lymphatics within thyroid, and lymph node metastases are common. The larger mass is cystic and contains papillary excresences. These tumors most often arise in middle-aged females.

Papillary Carcinoma

Well formed papillae lined by cells with characteristic empty-appearing nuclei, Orphan Annie eye nuclei, Inset

shows cells obtained by fine-needle aspiration.

Papillary carcinoma of the thyroid

Papillary carcinoma of thyroid

Follicular carcinoma.

At the center and to the right is a medullary carcinoma of thyroid. At the far right is pink hyaline material with the appearance of amyloid. These neoplasms are derived from the thyroid "C" cells and, therefore, have neuroendocrine features such as secretion of calcitonin.

Gross view of a pituitary adenoma. This massive nonfuntional adenoma has grown far beyond the confines of the sella turcica & has distorted the overlying brain.

This is a microadenoma of the anterior pituitary. Such microadenomas may appear in 1 to 5% of adults.

At high power, the tall columnar thyroid epithelium with Grave's disease lines the hyperplastic infoldings into the colloid. Note the clear vacuoles in the colloid next to the epithelium where the increased activity of the epithelium to produce increased thyroid hormone has led to scalloping out of the colloid.

Ongoing liver damage with liver cell necrosis followed by fibrosis and hepatocyte regeneration results in cirrhosis. This produces a nodular, firm liver. The nodules seen here are larger than 3 mm and, hence, this is an example of "macronodular" cirrhosis.

Here is another example of macronodular cirrhosis. Viral hepatitis (B or C) is the most common cause for macronodular cirrhosis. Wilson's disease and alpha-1-antitrypsin deficiency also can produce a macronodular cirrhosis.

A close-up view of a micronodular cirrhosis in a liver with fatty change demonstrates the small, yellow nodules. Micronodular cirrhosis may also be seen with Wilson's disease, primary biliary cirrhosis, and hemochromatosis.

Microscopically with cirrhosis, the regenerative nodules of hepatocytes are surrounded by fibrous connective tissue that bridges between portal tracts. Within this collagenous tissue are scattered lymphocytes as well as a proliferation of bile ducts.

Micronodular cirrhosis is seen along with moderate fatty change. Note the regenerative nodule surrounded by fibrous connective tissue extending between portal regions.

CHOLESTEROL STONES

PIGMENT STONES

CHOLESTEROLOSIS

•Collections of lipid laden histiocytes are seen in the lamina propria •Lipid is colorless in an H&E preparation causing the cytoplasm of the histiocytes to appear clear

Cholesterolosis.. Presence of lipid-laden, "foamy" histocytes within the lamina

propria

ACUTE HEMORRHAGIC CHOLECYSTITIS

At the upper right is a well-circumscribed neoplasm that is arising in liver. This is an hepatic adenoma

The cut surface of the liver reveals the hepatic adenoma. Note how well circumscribed it is. The remaining liver is a pale yellow brown because of fatty change from chronic alcoholism.

Here is an hepatocellular carcinoma. Such liver cancers arise in the setting of cirrhosis. Worldwide, viral hepatitis is the most common cause

Here is another hepatocellular carcinoma with a greenish yellow hue. One clue to the presence of such a neoplasm is an elevated serum alpha-fetoprotein. Such masses may also focally obstruct the biliary tract and lead to an elevated alkaline phosphatase.

Note the numerous mass lesions that are of variable size. Some of the larger ones demonstrate central necrosis

Note that this hepatocellular carcinoma is composed of liver cords that are much wider than the normal liver plate that is two cells thick

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