please show me amyloidosis based images referring from Robbins and Cotran pathology derived from inciet pyqs

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Amyloidosis - Robbins & Cotran Pathologic Basis of Disease

Here are all the key Robbins images for amyloidosis, organized by concept - highly relevant for INICET/PG entrance exam preparation.

IMAGE 1 - Mechanism of Amyloid Deposition (Fig. 6.44 / Robbins & Cotran)

Fig. 6.44 - Mechanism of amyloid deposition

What this shows: Light chain proteins, normal proteins (SAA, TTRwt), and variant proteins (TTRv) all undergo proteolysis or altered amino acid sequence → produce misfolded proteins → oligomerize → aggregate into amyloid fibrils → deposit extracellularly in tissues (shown in cardiac muscle) → disruption of architecture and tissue damage.

Exam point: All amyloid proteins converge on the same final common pathway - misfolded protein → β-pleated fibril → extracellular deposition.

IMAGE 2 - Pathogenesis of Amyloidosis (Fig. 6.45 / Robbins & Cotran)

Fig. 6.45 - Pathogenesis of amyloidosis showing all four types

What this shows: A comprehensive pathogenesis diagram with 4 pathways:

Pathway	Source	Protein	Type
Monoclonal B-cell/plasma cell proliferation	Plasma cells	Immunoglobulin light chains	AL amyloidosis
Aging/unknown stimulus	Liver cells (wild-type)	Wild-type transthyretin	ATTRwt amyloidosis
Chronic inflammation (macrophage activation → IL-1, IL-6)	Liver cells	SAA protein	AA amyloidosis
Genetic variants	Liver cells (variant TTR)	Variant transthyretin	ATTRv amyloidosis

The left panel shows the general mechanism: native folded protein → amyloidogenic intermediate → monomers assemble into β-sheet structure → fibril → pressure atrophy, tissue damage, organ dysfunction.

Exam point (INICET favourite): AA amyloidosis is the type associated with chronic inflammatory diseases (rheumatoid arthritis, tuberculosis, Crohn disease). The precursor protein is SAA (Serum Amyloid A), synthesized in the liver.

IMAGE 3 - Amyloid Structure (Fig. 5.35 / Robbins Basic Pathology)

Panel A - Amyloid fibril schematic:

Fig. 5.35A - Amyloid fibril structure showing Congo red binding sites

What this shows: Schematic of an amyloid fiber with four fibrils wound around one another. The Congo red dye (shown in red) binds at regularly spaced intervals along the β-pleated sheet conformation.

Panel B - Apple-green birefringence under polarized light:

Fig. 5.35B - Apple-green birefringence under polarized light

What this shows: Congo red stained amyloid viewed under polarized light - the pathognomonic apple-green (yellow-green) birefringence. This is the most specific diagnostic stain for amyloid.

Top INICET exam point: Congo red stain → pink/red under ordinary light; apple-green birefringence under polarized light - this is diagnostic. The birefringence is due to the cross β-pleated sheet configuration of amyloid fibrils.

IMAGE 4 - Histology: Congo Red Stain + Renal Amyloidosis (Fig. 6.46 / Robbins & Cotran; also Fig. 5.37 / Robbins Basic Pathology)

Fig. 6.46 / 5.37 - Amyloidosis histology: liver Congo red (A), polarized birefringence (B), renal glomerulus (C)

Panel A - Liver section stained with Congo red: pink-red amyloid deposits in walls of blood vessels and along sinusoids (space of Disse).

Panel B - Same field under polarizing microscope: yellow-green birefringence of the Congo red-stained deposits. This is the gold standard for amyloid diagnosis.

Panel C - Kidney amyloidosis: The glomerular architecture is almost totally obliterated by massive accumulation of amyloid (pink homogeneous material). The capillary loops are obliterated by confluent amyloid masses.

Exam points from this image:

Kidney is the most common and most serious organ involved in systemic amyloidosis

Amyloid begins in the mesangium and along the glomerular basement membrane

Leads to nephrotic syndrome → renal failure → most common cause of death in amyloidosis

In liver: amyloid first appears in the space of Disse (between hepatocytes and sinusoids)

Classification Table (Table 6.17 / Robbins & Cotran)

Category	Associated Disease	Fibril Protein	Precursor
AL amyloidosis	Multiple myeloma, monoclonal plasma cell proliferation	AL	Ig light chains (chiefly λ)
ATTRwt amyloidosis	Aging (males >70 years) - senile systemic amyloidosis	ATTRwt	Wild-type transthyretin
AA amyloidosis	Chronic inflammation (RA, Crohn, TB)	AA	SAA protein
ATTRv amyloidosis	Familial amyloidotic neuropathy, cardiac amyloidosis	ATTRv	Variant transthyretin
Aβ	Alzheimer disease (senile plaques)	Aβ	APP (amyloid precursor protein)
Endocrine	Type 2 DM (islets), medullary thyroid carcinoma	AIAPP / ACal	Islet amyloid peptide / Calcitonin

Key INICET Exam Points - Amyloidosis

Feature	Detail
Staining	Congo red → pink-red (light); apple-green birefringence (polarized)
Fibril diameter	~8-10 nm, non-branching, β-pleated sheet conformation
~95% composition	Fibril proteins; 5% = serum amyloid P (SAP) + glycoproteins
Most common type	AL amyloidosis (~2000-3000 new cases/year in USA)
Sago spleen	Amyloid limited to splenic follicles (white pulp)
Lardaceous spleen	Amyloid in splenic sinuses (red pulp) - maplike areas
Most common cause of death	Renal failure (kidneys most commonly and seriously involved)
Cardiac amyloidosis presents as	Restrictive cardiomyopathy + arrhythmias
Diagnosis	Rectal biopsy / abdominal fat aspirate stained with Congo red; abdominal fat most specific
Endocrine amyloid in medullary thyroid Ca	Derived from calcitonin - a helpful diagnostic feature
β₂-microglobulin amyloid	Old complication of dialysis (now rare with improved membranes) - carpal tunnel syndrome
Macroglossia	AL amyloidosis involving tongue (tumour-forming amyloid)

Sources: Robbins, Cotran & Kumar Pathologic Basis of Disease (ISBN 9780443264528), Figs. 6.44, 6.45, 6.46; Robbins & Kumar Basic Pathology (ISBN 9780323790185), Figs. 5.35, 5.37

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