Pathology Practical (SPECIMENS)

Introduction to Pathology Practical (Specimens)

  • Following Specimens are Important for Viva and spotting purposes, this presentation contains important morphological and microscopy points.

Osteoclastoma

  • Osteogenic sarcoma or osteoclastoma is the most common primary malignant bone tumour.
  • Classically, the tumour occurs in young patients between the age of 10 to 20 years.
  • The tumour arises in the metaphysis of long bones, most commonly in the lower end of femur and upper end of tibia (i.e. around knee joint).
  • G/A
    • The tumour appears as a grey-white, bulky mass areas of haemorrhages and necrotic bone at the metaphyseal end of a long bone of the extremity, generally sparing the articular end of the bone.
    • Codman’s triangle formed by the angle between lifting of periosteum and underlying surface of the cortex may be grossly identified.
    • Cut surface of the tumour is grey-white with areas of haemorrhages and necrotic bone
  • Microscopy –
    • Scarcoma cells
    • Osteogenesis

Pyelonephritis

  • Chronic pyelonephritis is a chronic tubulointerstitial disease resulting from repeated attacks of inflammation and scarring.
  • G/A –
    • The kidneys are usually small and contracted, weighing less than 100 gm each, showing unequal reduction.
    • The outer surface of the kidneys is irregularly scarred. These scars are of variable size and show irregular depressions on the cortical surface.
    • The pelvis is dilated and calyces are blunted and may contain renal stone taking its shape called staghorn stone.
  • M/E –
    • The predominant microscopic changes are seen in the interstitium and tubules:
      1. The interstitium shows chronic inflammatory infiltrate, chiefly composed of lymphocytes, plasma cells and macrophages with pronounced interstitial fibrosis.
      2. The tubules show varying degree of atrophy and dilatation. Dilated tubules may contain colloid casts producing thyroidisation of tubules.
      3. The wall of dilated pelvicalyceal system shows marked chronic inflammation and scarring.
      4. There is often periglomerular fibrosis and hyalinisation of some glomeruli.

Renal Cell Carcinoma

  • Renal cell carcinoma (RCC) or hypernephroma or adenocarcinoma comprises 70-80% of all renal cancers and occurs most commonly in 50 to 70 years of age.
  • G/A –
    • The tumour commonly arises from a pole, most often upper pole, of the kidney as a solitary and unilateral tumour.
    • The tumour is generally large, golden yellow and circumscribed.
    • Cut section of the tumour commonly shows large areas of ischaemic necrosis, cystic change and foci of haemorrhages.
    • Another feature is the frequent presence of tumour thrombus in the renal vein
  • M/E –
    • A variety of patterns of tumour cells are seen such as solid, acinar, tubular, trabecular, cord and papillary arrangements in a delicate fibrous stroma.
    • Tumour cells are generally of 2 types –
      • – clear
      • – granular

Benign Hyperplasia Prostate

  • Non-neoplastic tumour-like enlargement of the prostate is a very common condition in men, frequently above the age of 50 years.
  • G/A –
    • The enlarged prostate is nodular, smooth and firm and weighs 2-4 times its normal weight (normal average weight 20 gm).
    • The appearance on cut section shows nodularity having varying admixure of yellowish pink, soft, honey-combed appearance (glandular hyperplasia) and firm homogeneous appearance (fibromuscular hyperplasia).
  • M/E
    • There is hyperplasia of all three tissue elements in varying proportions -glandular, fibrous and muscular
      1. Glandular hyperplasia predominates in most cases and is characterised by exaggerated intra-acinar papillary infoldings with delicate fibrovascular cores. Glands are lined by two layers of epithelium.
      2. Fibromuscular hyperplasia appears as aggregates of spindle cells forming an appearance similar to fibromyoma of the uterus.

SEMINOMA TESTIS

  • Seminoma is the commonest malignant tumour of the testis, constituting 45% of all testicular germ cell tumours and corresponds to dysgerminoma in the female gonad.
  • G/A –
    • The involved testis is enlarged (upto 10 times) but tends to maintain its normal contour since the tumour rarely invades the tunica.
    • Cut section of the affected testis shows homogeneous, grey-white lobulated appearance.
  • M/E –
    • Tumour cells
    • Stroma

TERATOMA OVARY

  • Benign cystic teratoma or dermoid cyst of the ovary is more frequent in young women in their active reproductive life.
  • Teratoma is a tumour composed of tissue derived from three germ cell layers—ectoderm, mesoderm and endoderm.
  • G/A –
    • Benign cystic teratoma is characteristically a unilocular cyst, 10-15 cm in diameter.
    • On sectioning, the cyst is filled with paste-like sebaceous secretions and desquamated keratin admixed with masses of hair.
    • The cyst wall is thin and opaque grey-white.
    • Quite often, the cyst wall shows a solid prominence where tissue elements such as tooth, bone, cartilage and other odd tissues are present.
  • M/E –
    • Viewing a benign cystic teratoma in different microscopic fields reveals a variety of mature differentiated tissues, producing kaleidoscopic appearance.
    • Ectodermal derivatives are most prominent.
    • The lining of the cyst wall is by stratified squamous epithelium and its adnexal structures such as sebaceous glands, sweat glands and hair follicles.
    • Tissues of mesodermal and endodermal origin are commonly present and include bronchus, intestinal epithelium, cartilage, bone, smooth muscle, neural tissue, salivary gland, retina, pancreas and thyroid tissue.

Serous Cystadenoma Ovary

  • These tumours arise from the ovarian surface (coelomic) epithelium which differentiates along tubal-type of epithelium.
  • G/A –
    • Serous tumours of benign, borderline and malignant type are large and spherical masses.
    • Cut section of benign tumours is unilocular while larger cysts are multilocular and contain clear watery fluid
  • M/E –
    • The cyst is lined by properly-oriented low columnar epithelium.
    • The lining cells may be ciliated and resemble tubal epithelium

FIBROADENOMA

  • Fibroadenoma is a benign tumour of fibrous and epithelial elements of the breast.
  • It is the most common benign tumour of the breast in reproductive life.
  • G/A –
    • Typically fibroadenoma is a small (2-4 cm diameter), solitary, well-encapsulated, spherical or discoid mass.
    • The cut surface is firm, grey-white, slightly myxoid and may show slit-like spaces.
  • M/E –
    • The arrangement between fibrous overgrowth and ducts may produce 2 types of patterns: intracanalicular and pericanalicular
      1. Intracanalicular pattern is one in which the stroma compresses the ducts so that they are reduced to slit-like clefts lined by ductal epithelium and may appear as cords of epithelial elements surrounding masses of fibrous tissue.
      2. Pericanalicular pattern is characterised by encircling masses of fibrous tissue around the patent or dilated ducts.

LEIOMYOMA (Pathology Practical)

  • Hyaline change (or hyalinisation) representsan end-stage of many diverse and unrelated lesions.
  • It may be intracellular or extracellular. Hyaline degeneration in leiomyoma, a benign smooth muscle tumour, is an example of extracellular hyaline in the connective
    tissue.
  • Uterine leiomyomas may be subserosal, intramural or submucosal.
  • G/A –
    • The tumour is circumscribed, firm to hard. Cut surface presents a whorled appearance.
    • The hyalinised area in the tumour appears glassy and homogeneous
  • M/E –
    • There is mixture of smooth muscle fibres and fibrous tissue in varying proportions. Some of the muscle fibres may be cut longitudinally and some
      transversely.
    • Whorled arrangement of muscle fibres admixed with fibrous tissue is seen at places.
    • Nuclei of the smooth muscle fibres are short, plump and fusiform while those of the fibroblasts are longer, slender and curved
    • Hyaline degeneration which is the commonest change due to insufficient blood supply appears as pink, homogeneous and acellular.

PAPILLARY CARCINOMA (Pathology Practical)

  • Papillary carcinoma is the most common type of thyroid cancer comprising about 60% of cases, seen more frequently in females.
  • G/A –
    • Papillary carcinoma may range from microscopic foci to nodules upto 10 cm in diameter and is generally poorly delineated.
    • Cut surface of the tumour is greyish-white, hard to scar-like
  • M/E –
    • Papillary pattern: Papillae composed of fibrovascular stalk and covered by single layer of tumour cells.
    • Tumour cells: The tumour cells have overlapping pale nuclei (ground glass appearance) and clear or oxyphil cytoplasm.
    • Invasion: The tumour cells invade the capsule, and intrathyroid lymphatics.
    • Psammoma bodies: Almost half of papillary carcinomas show typical, small concentric calcified spherules in the stroma

NODULAR GOITRE (Pathology Practical)

  • Nodular goitre is regarded as end-stage of long-standing simple goitre.
  • It is characterised by tumour-like enlargement of the thyroid gland and characteristic nodularity.
  • G/A –
    • The thyroid shows asymmetric and extreme enlargement weighing 100-500 gm (normal weight 15-40 gm).
    • The 5 cardinal gross features are: nodularity with poor encapsulation, fibrous scarring, haemorrhages focal calcification, and cystic degeneration.
    • Cut surface of the gland shows multinodularity
  • M/E –
    • Partial or incomplete encapsulation.
    • The follicles of varying size from small to large and lined by flat to high epithelium.
    • Areas of haemorrhages, haemosiderin-laden macrophages and cholesterol crystals.
    • Fibrous scarring and calcification in the nodules.
    • Cystic degeneration.

BRONCHOPNEUMONIA

  • Bronchopneumonia or lobular pneumonia is infection of terminal bronchioles that extends into the surrounding alveoli resulting in patchy consolidation of the lung.
  • G/A –
    • Bronchopneumonia is identified by patchy areas of red or grey consolidation affecting one or more lobes, more often bilaterally and involving lower zones of lungs more frequently.
    • On cut surface, patchy consolidated lesions appear dry, granular, firm, red or grey in colour, 3 to 4 cm in diameter.
    • These lesions are slightly elevated over the surface centred around a bronchiole, best picked up by feeling with fingers on cut section.
  • M/E –
    • Changes of acute bronchiolitis characterised by acute inflammatory cells in the bronchiolar walls.
    • Suppurative exudate of neutrophils in the peri-bronchiolar alveoli.
    • Widening of alveolar septa by congested capillaries and leucocytic infiltration.
    • Alveoli away from the involved area contain oedema fluid

LOBAR PNEUMONIA

  • Lobar pneumonia is an acute bacterial infection of a large portion of a lobe/lobes of one or both the lungs.
  • This initial stage of lobar pneumonia represents the early acute inflammatory response to bacterial infection that lasts for 1 to 2 days.
  • G/A –
    • The affected lobe is enlarged, heavy, dark red and congested.
    • Cut surface exudes blood-stained frothy fluid.
  • M/E –
    • Dilatation and congestion of capillaries in the alveolar walls.
    • Pale eosinophilic oedema fluid in the air spaces.
    • A few red cells and neutrophils in the intra-alveolar fluid
    • Bacteria may be demonstrable by Gram’s staining

BRONCHIECTASIS (Pathology Practical)

  • Bronchiectasis is abnormal and irreversible dilatation of the bronchi and larger bronchioles.
  • G/A –
    • Bilateral involvement of lower lobes of lungs is seen more frequently.
    • The pleura is usually fibrotic and thickened.
    • Cut surface of affected lower lobes shows characteristic honey-combed appearance due to dilated airways containing muco-pus and thickening of their walls.
  • M/E –
    • Infiltration of the bronchial walls by acute and chronic inflammatory cells with destruction of normal muscle and elastic tissue with replacement fibrosis.
    • Fibrosis of the intervening lung parenchyma and interstitial pneumonia.
    • Normal, ulcerated or squamous metaplastic, bronchial epithelium

PULMONARY OEDEMA (Pathology Practical)

  • Pulmonary oedema is a common clinical and pathologic condition resulting from haemodynamic disturbances or from direct increase in capillary permeability.
  • G/A –
    • The lungs are voluminous, heavy, firm, wet and show marked pitting on pressure. Initially fluid accumulates in the basal region of the lower lobes.
    • Cut surface of lungs permits escape of frothy blood-tinged fluid due to mixture of air and oedema fluid.
  • M/E –
    • Initially, alveolar septa are widened due to accumulation of oedema fluid
    • Later, the proteinaceous fluid appears in the alveolar spaces and appears as pink granular material and may have some admixed RBCs and macrophages

HYDATID CYST LIVER (Pathology Practical)

  • Hydatid disease occurs as a result of infection by the larval stage of the tapeworm, Echinococcus granulosus.
  • The liver is a common site for development of hydatid cyst.
  • G/A –
    • The cyst may vary in size and may attain the size over 10 cm in diameter.
    • The cyst wall has laminated membrane and the lumen contains clear fluid.
  • M/E –
    • The cyst wall is composed of 3 distinguishable
      zones :-
      1. Outer Pericyst is the inflammatory reaction by the host consisting of mononuclear cells, eosinophils some giant cells and surrounded peripherally by fibroblasts.
      2. Ectocyst is the characteristic intermediate layer composed of acellular, chitinous laminated, hyaline material.
      3. Endocyst is the inner germinal layer bearing the daughter cysts and scolices projecting into the lumen

CIRRHOSIS LIVER (Pathology Practical)

  • Cirrhosis of the liver is a diffuse disease having disorganised lobular architecture and formation of nodules separated by irregular bands of fibrosis from one another.
  • G/A –
    • Cirrhosis is categorised by the size of nodules— micronodular if the nodules are less than 3 mm, macronodular if the nodules are bigger than 3 mm, and mixed if both small and large nodules are seen.
    • On sectioned surface, the grey-brown nodules are separated from one another by grey-white fibrous septa.
  • M/E
    • The etiologic diagnosis in routine microscopy is generally not possible. The salient features of cirrhosis are as under:
      1. Lobular architecture of hepatic parenchyma is lost and central veins are hard to find.
      2. Fibrous septa divide the hepatic parenchyma into nodules.
      3. The hepatocytes in the surviving parenchyma form regenerative nodules having disorganised masses of hepatocytes.
      4. Fibrous septa contain some mononuclear inflammatory cell infiltrate and proliferated bile ductules

CHRONIC CHOLECYSTITIS WITH CHOLELITHIASIS

  • Chronic cholecystitis is the commonest type of gall bladder disease.
  • G/A –
    • The gallbladder is generally contracted and the wall is thickened.
    • Cut section of wall of gallbladder is grey-white due to dense fibrosis.
    • The mucosal folds may be thickened, atrophied or flattened.
    • The lumen commonly contains gallstones, most often multiple multifaceted mixed type, followed by pure cholesterol gallstones in descending order of frequency
  • M/E –
    • Penetration of mucosa deep into the wall of the gall bladder upto the muscularis layer to form Rokitansky-Aschoff sinuses.
    • Variable degree of chronic inflammatory cells (lymphocytes, plasma cells and macrophages) in the lamina propria and subserosal layer.
    • Variable degree of fibrosis and thickening of perimuscular layer

Mucoid Carcinoma Colon (Pathology Practical)

  • Colorectal carcinoma comprises the commonest form of visceral cancer.
  • The most common location is rectum.
  • G/A –
    • The tumour has distinctive features in right and left-sided colonic cancer.
    • The right-sided growth, tends to be fungating, large, cauliflower-like, soft and friable mass projecting into the lumen
    • The left sided growth, on the other hand, has napkin-ring configuration
      i.e. it encircles the bowel wall circumferentially with increased fibrous tissue forming annular ring with central mucosal ulceration
  • M/E –
    • The microscopic appearance on right-sided and left-sided colonic cancer is similar:
      1. The tumour has infiltrating glandular pattern in the colonic wall with varying grades of differentiation of tumour cells.
      2. About 10% cases show mucin-secreting colloid carcinoma with pools of mucin

LIPOMA (Pathology Practical)

  • Lipoma is a common benign tumour occurring in the subcutaneous tissues.
  • G/A –
    • The tumour is small, encapsulated, round to oval.
    • The cut surface is soft, lobulated, yellowish and greasy
  • M/E –
    • A thin fibrous capsule surrounds the periphery.
    • The tumour is composed of lobules of mature adipose cells separated by thin fibrous septa

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