BASIC RADIATION PATHOLOGY

CHIRAAG D. PATEL, MD

PGY-2

STONYBROOK UNIVERSITY MEDICAL CENTER

DEPARTMENT OF PATHOLOGY

CONFLICT OF INTEREST

Neither I nor my family have any financial or conflicts of interest to disclose.

OUTLINE• Basic radiation physics

• Radiation changes

• biology• changes in prostate• changes in breast

• Acute radiation syndrome

RADIATION PHYSICSEXPOSURE

Ionization

Ionization is the process of removing an electron from an electrically neutral atom to produce an ion pair. An ion is an atom or subatomic particle with a positive or negative charge.

Ionization negative ion (electron)

positive ion: atom with 3 protons, 2 electrons

X-ray enters atom and strikes electron, knocking it out of its orbit and creating two ions (ion pair). The ejected electron is the negative ion and the atom with a net positive charge is the positive ion.

+++

PENATRATING ABILITY OF DIFFERENT FORMS OF RADIATION

Average effective dose to the human population in the US:

Dominated by radon exposure which is natural

NCRP, July 2006

Direct: Interaction directly with critical targets in the cell (DNA)

High LET is usually direct in action

(alpha particle, neutron, proton)

Indirect: Free radicals are produced which diffuse and cause damage

Low LET (x ray, gamma ray)

Linear energy transfer =measure of the energy transferred to material as an ionizing particle travels through it. 

ACTION

Biomolecular Action of Ionizing Radiation; Editor:Shirley Lehnert, 2007

NEUTRON (USUALLY DIRECT)

Biomolecular Action of Ionizing Radiation; Editor:Shirley Lehnert, 2007

The principle chemical alteration induced in cells by IONIZING RADIATION that most closely correlates with cell death is?

A. Lipid peroxidation

B. Oxidative damage to proteins

C. Protein-protein cross-links

D. Damage to mitochondria

E. Damage to nuclear DNA

RADIATION CHANGES

Acute tissue injury

Chronic tissue injury

Seen in both early and late responding tissues.

Degree of change evident is different

TIMELINE

http://www.cs.unm.edu/~compmed/seminars/LT_MedPhys3.pdf

Preventing or reducing late side effects of radiation therapy: radiobiology meets molecular pathology, Bentzen S, NRC, 9/2006

RADIATION CHANGES PROSTATE

In the non-neoplastic irradiated prostate, nuclear enlargement and smudged chromatin are the most notable changes.

THE PRESERVATION OF AT LEAST A FOCAL BASAL CELL LAYER IS A COMMON FINDING

Basal cellsNormal - single layer (left), Abnormal - nuclear enlargement, irregular, potato-shaped nuclei are pathognomonic for basal cells.

Normal Basal cell post radiation

Identification of irradiated cancer is a problematic area in pathology, now that increased numbers of post-treatment biopsies are being performed. Early changes include cytomegaly, vacuoles, and nucleomegaly with persistent single and occasionally double nucleoli in each nucleus (left). Later changes include atrophy and sometimes cytoplasmic vacuolation, with the nucleoli now being inconspicuous.

Early radiation change Late radiation change

In this matched set of photomicrographs from the same patient, compared with pre-treatment grade 3 cancer (RIGHT), the main post-treatment change is atrophy (LEFT). Note, however, the maintenance of infiltrative pattern, angulated acini, absence of basal cells, and inspissated luminal blue mucin characteristic of cancer. Depending on the duration of irradiation, one may see all atrophic cancer acini, unchanged acini, or a combination of atrophic and unchanged acini.

Pretreatment Gleason grade 3Post treatment radiation changes

This biopsy was performed due to rising PSA several years after radioactive seed implantation (brachytherapy) for prostate cancer. The cytologic and architectural atypia seen here is within the spectrum of radiation-induced changes.  

cytokeratin 34bE12 (CK903)

In cases in which the history of irradiation is not given or is uncertain, stromal and vascular changes can cue the pathologist to recognize radiation effect. The stroma becomes fibrotic, and the cellularity of normal vessel walls (normal: left) increases because of smooth muscle proliferation (right).

Gaudin PB, Zelefsky MJ, Leibel SA, et al. Histopathologic effects of three- dimensional conformal external beam radiation therapy on benign and malignant prostate tissues. Am J Surg Pathol. 1999;23:1021–1031.

Gaudin PB, Zelefsky MJ, Leibel SA, et al. Histopathologic effects of three- dimensional conformal external beam radiation therapy on benign and malignant prostate tissues. Am J Surg Pathol. 1999;23:1021–1031.

RADIATION CHANGES BREAST

Low magnification of a lobule shows several acini (ductules) with hyperchromatic nuclei.

Low magnification of another area displays thickening of periacinar basement mem- branes and epithelial cells with enlarged, hyper- chromatic nuclei.

Essentials of Diagnostic Breast Pathology: A Practical Approach By Farid Moinfar

Higher magnification displays a ductule with enlarged, hyperchromatic nuclei of luminal epithelial cells. Note the thickening of basement membrane and the presence of a few myoepithelial cells with enlarged nuclei. Luminal microcalcification is evident.

At higher magnification, several acinar structures (ductules) exhibit marked degenerative epithelial cell changes, including smudge chromatin pattern and large, vacuolated cytoplasm.

Essentials of Diagnostic Breast Pathology: A Practical Approach, Farid Moinfar

Note the intralobular sclerosis and thickening of the basement membranes.

Essentials of Diagnostic Breast Pathology: A Practical Approach, Farid Moinfar

Digital Atlas of Breast Pathology, M Singh, Department of Pathology, Stony Brook University Medical Center

Ductal carcinoma in situ with radiation effect, high power.Note the extreme nuclear atypia.

High magnification of sever- al blood vessels and capillaries shows radiation-induced changes characterized by atypical endothelial cells with enlarged and hyperchromatic nuclei. The chromatin pattern is, however, blurred.

Essentials of Diagnostic Breast Pathology: A Practical Approach, Farid Moinfar

High magnification of sever- al blood vessels and capillaries shows radiation-induced changes characterized by atypical endothelial cells with enlarged and hyperchromatic nuclei. The chromatin pattern is, however, blurred.

MOST COMMON FINDINGS?

Radiation-induced Histopathologic Changes of the BreastThe Effects of Time, Moore, GK, Am J Surg Pathol, Jan 2004

Matched pretreatment and Post RT biopsy or mastectomy specimen from 117 patients with a range of 1-229 months post RT.

Findings:Pre vs post RT- significant

However, changes over time (1 year,3year, 6 year post RT) were not significant

ACUTE RADIATION SYNDROME

Short-Term and Long-Term Health Risks of Nuclear-Power-Plant Accidents, NEJM, Glatstein, E et al 2011

NEOPLASTIC

NEOPLASTICSEQUELA OF IONIZINGRADIATION

INCREASING DOSE

SUBCLINICAL

BONE MARROW

(SOF)Reversible if

heterogenous irradiation

NEUROVASCULAR

(SOF)

GASTROINTESTINAL

(SOF)

( MOF)

1 Gy

50 Gy

30 Gy

6-8 Gy

4 Gy

The Classical Paradigm of the ARS

Acute radiation syndromes

1 rad = 0.01 gray2-8 gray

Acute radiation syndromes

1 rad = 0.01 gray10-20 gray

Loss of GI Epithelial Cells:

Loss of mature cells (villus) because of a lack of stem cells to repopulate.

The Gastro-intestinal Syndrome

Control 16 Gy Day 5

Disrupt Crypts Denudation of villi

Fluid and Electrolyte Loss

Endotoxemia, Bacteremia

DEATH

Acute radiation syndromes

1 rad = 0.01 gray> 30 gray

ACUTE RADIATION SYNDROME (ARS)

Cardiovascular/Neurologic• Mixed picture• Burning of skin within minutes• Pyrexia• Ataxia• Decreased higher cortical and motor function• Hypotension, increased intracranial pressures within minutes

to hours of exposure• Autopsy findings: Microvascular & endothelial damage, focal

brain hemorrhage & necrosis, white matter edema, demyelination

THE END

Pathways to Contamination following Chernobyl

American Scientist, 2005

Process of Reoxygenation

Experiments of Warren Sinclair: Survival curves during cell cycle

M>G2>G1>early S>late S for sensitivity

RESULT

2 Proton + 2 Neutron

1 Electron

Surplus energy

Main components of natural background radiation:

Building materials—U, Th

Solar flares, outer space

Ingested is 40-potassium from foodInhaled is Rn

Locations with high backgrounds: Brazil, France, India, Egypt, Nine Island (Pacific)

Cosmic ray exposure varies with altitude: avg in US is 26mrems or .26mSv at sea level. Increase this 2x for each 2000m increase in altitude.

Radiation-induced Effects in Relation to timing of effects:

RADIOBIOLOGY

FOUR RS OF RADIOBIOLOGY

Repair

Tumor and normal cells, benefits normal cells

Repopulation

Affects mostly tumor cells, negative consequence of fractionation

Reassortment

Redistribution of cells within the cell cycle—tumor and normal cells, benefits killing of tumor cells

Reoxygenation

Affects tumor cells, enhances therapy

Diffusion of Oxygen through Tumor Tissue

Oxygen can generally diffuse 70um at the arterial end of the capillary and lessat the venous end.

4RSTissue type Repair Redistribution Repopulation Reoxygenation

Time course 1-4h 4-8h Early: 2-4wLate: 6w

1-4d

NON-NEOPLASTIC SEQUELA OF IONIZING RADIATION

NEOPLASTIC

NEOPLASTICSEQUELA OF IONIZINGRADIATION

CASE REPORT: BELGIUM 200648 year old male, worked in radiation facility, presented with vomiting for 4d and possible gastroenteritis

Decrease in lymphocytes that continued with BM aplasia

Discovered that the shutter had not been working in radiation facility and his exposure was 4.5Gy

Gave cytokine therapy at day 29, responded with increased lymphocytes at day 30

Evidence for subclinical liver and cardiac damage (oxysterol levels elevated)

Alive and asymptomatic now

DAKAR ACCIDENT 2008Lost Ir192 source, accidentally stored near workplace, estimated 63 potentially exposed individuals

4 presented with burns, 2 had vomiting and decreased lymphocyte counts

Dose estimates: 2.6Gy for one, 1.2Gy for the other

Treated both with cytokine therapy and they responded

The Experimental ARS in PrimatesKidney Liver

lungs Jejunum

Liver, CD31 Lungs, vWf

» Late death of two animals, on day 23 and 30

• Despite the presence of circulating platelets and WBC

• Macroscopic lesions: necrosis, haemorrhages

• Biochemical modifications: gGT, creatinin, …

From

Bert

ho, 2

00

5

Creatinin

Days after irradiation

0 20 40 60 80m

ol/

l

0

50

100

150

200

250

300

350

After

After

Before

Manip VIII : 29-30-31 janv. 02

AA208,AA470 = mo prélevéé après irradAA870 = mo prélevée avant irrad

Multiple Organ Failure (MOF) or Multiple Organ Dysfunction Syndrome ?? A general picture of a multiple organ dysfunction

Provided by Dr. Patrick Gourmelon

1 2 3 4 5 6 7 8 9 10 11

DeathTime after irradiation (weeks)

Haematopoieticsyndrome

Gastrointestinaldisease

Cutaneoussyndrome

Lungdisease

Renal Failure

Liverdysfunction

PBSCT

Lung oedema

GI bleedingDiarrhoea

Aplasia Hemophagocytosis

Massive exudateErythema, Blister

Clinical Picture Tokaï-Mura Accident ( Japan 1999)

Provided by Dr. Patrick Gourmelon

Radiation-Induced MOFRadiation-Induced MOFIR

Induction of Genes for Cytokines

Release of Tissue Factor

Tumor necrosis factor-AlphaIL-1, -6, -8

Tumor growth factor-beta IL-4, -10, 12

Pro-Inflammation Anti-Inflammation

Clottingcascadeactivation

DICSIRS CARS

MOF SIRS-Systemic inflammatory response syndromeCARS-Compensatory anti-inflammatory response syndrome

Activation of Endothelium

Trauma

Proportion of second cancers attributable to radiotherapy treatment in adults: a cohort study in the US SEER cancer registries

[HTML] from thelancet.com

AB de Gonzalez, RE Curtis, SF Kry, E Gilbert… - The Lancet …, 2011 - Elsevier

ACUTE TISSUE CHANGES

Acute changes are typically inflammatory

• Erythema• Edema• Dry > moist desquamation• Hemmorhage • Necrosis

Changes are the result of cells dying in the tissues within the radiation field.

ACUTE TISSUE CHANGES

Cellular death attracts inflammatory cells

• Radiation injury of these cells further exacerbates the inflammation.

Severity proportional to the dose received

Inversely proportional to time span of dose

Other sources of trauma such as abrasion and infection will increase severity

ACUTE TISSUE CHANGESFollowing the acute changes there are two possible outcomes.

• Regeneration - Replacement of the cells lost by cells of the same type.

• May be complete or partial and is comonly seen in rapidly dividing cell lines and those arising from blast cells

• Generally is a low dose phenomenon but may occur in some tissues at relatively high doses.

• Influenced by the response of other cells in the area (critical cells)

ACUTE TISSUE CHANGES

Following acute tissue injury the tissue may also undergo replacement.

• Original cell population replaced by different population – usually fribroblasts

• Results in permanent loss of the original cell population and its function.

• Occurs in tissues with long cell cycle times• Tends to occur more commonly at high doses

CHRONIC TISSUE CHANGES

Changes manifest after healing process

• May be minimal if regeneration is dominant • Depigmentation • Hair loss and thinning• Atrophy• Scar formantion and strictures• Non-healing ulcers or necrosis

CHRONIC TISSUE CHANGES

Chronic changes may supersede apparent healing.

• Occurs when a slowly dividing critical cell line dies off after early healing of rapidly dividing cell lines.

• Classic example is loss of vascular supply to a tissue such as the intestine after mucosal regeneration has occurred.

CHRONIC TISSUE CHANGES

• Or, if a subsequent insult (infection, trauma, etc) exceeds the repair tolerance of the tissue

• Classic example is a non-healing surgical incision made in a radiation field.

• Another example is bone necrosis is a radiation field months to years after soft tissues in the radiation field have healed.

LATE VRS. EARLY RESPONDING TISSUESAcute and chronic changes are both seen in either:

• Early (rapidly dividing cell lines)• Or late (slowly dividing cell lines) responding tissues• Generally speaking the changes are less evident in late

responding tissue unless necrosis occurs.

OTHER FACTORS IN RADIATION RESPONSEVolume of tissue irradiated

• Increased volume increases effectsOxygenation at the cellular level

• Normal cells are typically 100% oxygenated• Tumor tissues may contain hypoxic areas.

Presence of some chemicals

• Some chemotherapy agents increase effects• Some drugs such as Amophostine mitigate effects

OTHER FACTORS IN RADIATION RESPONSEDose Rate

• Decreased dose rate decreases effects

Cellular Kenetics

• Growth fraction - The percentage of cells actually moving through the cell cycle.

• Can blunt effects > repopulation • Can increase effects > more cells irradiated in Mitosis

OTHER FACTORS IN RADIATION RESPONSECellular Kinetics

• Cell loss fraction – number of cells naturally being lost from the cell population.

• Increased loss Fx. - Accelerates effects• Decreased loss Fx. – Blunts effects.

Cell type

• Non-cycling population blunts effects markedly.• Critical cell line may supersede and cause effects.