Molavi Chapter 5 - Ditzels (Common specimens)

Question 1

Appendicitis histology

Answer 1

Islands of residual colonic mucosa in an otherwise fibropurulent mess.

On histology chronic inflammation is not significant, but neutrophils are.

Things to look out for: Carcinoid in the tip, pools of mucin in the wall indicating mucinous neoplasm.

Question 2

Chalazion histology

Answer 2

Inflammation of squamous mucosa with abundant inflammatory cells and granulomatous inflammation is typical. Lipogranulomas are characteristic.

When one of these is submitted as a biopsy, your job is to rule out malignancy.

Question 3

Lipogranuloma

Answer 3

Granulomatous inflammatory soft tissue reaction, consisting of lipid deposition and/or an oil-like substance commonly associated with injections, trauma or secondary to systemic diseases.

Question 4

Cholesteatoma histology

Answer 4

A cyst usually dominated by flaky keratin contents.

Other features include inflammation, cholesterol clefts, and foreign body giant cells.

Ddx that you need to differentiate is: inflammatory polyp, paraganglioma, middle ear adenoma, meningioma, shwannoma.

Question 5

Cornea histology

Answer 5

• Typical layers:
  
  1. Outer squamous epithelium
  2. Hyalinized, acellular layer called Bowman’s layer
  3. Thick layer of paucicellular stroma
  4. Another hyalinized, acellular membrane called Descemet’s membrane
  5. A thin endothelium
• You are looking for:
  
  • Inflammation
  • Infectious organisms (bacteria, acanthamoeba keratitis, HSV)
  • Bumps on the Descemet membrane called guttae, seen in Fuchs dystrophy

Question 6

Odontogenic cysts / Jaw cysts

Answer 6

• Non-neoplastic:
  
  • Periapical cyst (inflammatory cyst at tooth root)
  • Dentigerous cyst (fluid inclusion cyst associated with an impacted tooth), sometimes with islands of odontogenic epithelium (
• Neoplastic:
  
  • Ameloblastoma (cyst lined by stellate reticulum-like epithelium)
  • Keratocystic odontogenic tumor (undulating, flat squamous epithelium with parakeratosis)

Question 7

Osteoarthritis histology

Answer 7

1. Eroded cartilage
2. Irregular cartilage mineralization
3. Thickening of subchondral bony trabeculae
4. Myxoid degeneration of subchondral bone, forming cyst-like spaces

Question 8

Osteonecrosis histology

Answer 8

1. Loss of basophilia and nuclei in the marrow and fat cells, osyeocytes missing from lacunae
2. Fat necrosis
3. Hemorrhage

Question 9

Gallbladder histology

Answer 9

• Normal features:
  
  • Sinele layer of columnar epithelium in folds overlying fibromuscular layers
  • Rokitansky-Aschoff sinuses (infolded mucosa)
  • Ducts of Luschka (accessory cholecystohepatic ducts connecting the GB and intrahepatic ducts directly, 10% of people)
• Inflammation: cholecystitis can range from mild lymphoplasmocytic to transmural acute inflammation.
• Cholesterolosis: The accumulation of foamy macrophages under the epithelial surface.
• Dysplasia is rare. If you find any, go back for more tissue.

Question 10

Ganglion cyst histology

Answer 10

• Not a true cyst as there is no epithelium (though there may be synovial cells lining a cavity) – more often just myxoid degenration of soft tissue
• Rule out:
  
  • Giant cell tumor of tendon sheath
  • Fibroma

Question 11

Heart valve histology

Answer 11

• Things to look for:
  
  • myxoid degeneration (shown)
  • calcifications
  • adherent vegetations
• All heart valves get a gram stain and GMS stain to rule out colonization by bacteria or fungus

Question 12

Hernia sac histology

Answer 12

• Typically fibroadipose tissue lined with mesothelium (may be reactive or proliferative)
• Rule out:
  
  • presence of vas deferens tissue in the sample (Immediate call to the surgeon!!!)
  • incarcerated bowel
  • Metastatic tumor

Question 13

Intervertebral disc histology

Answer 13

• Fibrocartilage and pulpyy mixoid gel (nucleus pulposus), possibly with fragments of bone
• Rule out:
  
  • Tumors
  • Inflammation

Question 14

Nucleus pulposus

Answer 14

The soft, gelatinous central portion of the intervertebral disk that moves within the disk with changes in posture

Question 15

Temporal artery histology

Answer 15

• Identify the vessel layers and the undulating internal elastic lamina, which should be continuous in healthy tissue.
• Effects of aging: Medial calcification, intimal thickening, reduplication and small breaks in internal elastic lamina
• Rule out:
  
  • Giant cell arteritis (shown): Transmural inflammation or pockets at the junction of the intima and media that may be acute or chronic (giant cells are NOT required).

Question 16

Lipoma histology

Answer 16

• Neoplasm of mature fat cells. Small septa of fibrous tissue are fine, but if smooth muscle or spindle cells are present it may indicate a lipoma variant.
• Rule out:
  
  • Lipoma variants
  • Well-differentiated liposarcoma (shown) (large, deep seated circumscribed mass in atypical location withh thick fibrous bands with atypical cells with hyperchromatic nuclei and lipoblasts on histology)

Question 17

Features of a liposarcoma

Answer 17

Lipoblasts are like adipocytes still accumulating fat into multiple vacuoles centered on the nucleus. They will have thin wisps of normal cytoplasm in-between these vacuoles.

Question 18

Neuroma histology

Answer 18

• Tangle of small nerve fibers on a fibrous background
• Usually associated with prior surgery – with the exception of Morton’s neuroma (fibrosis and degeneration of the nerves of the feet)
• Rule out: Nerve sheath tumor