Hematology and Oncology - Pathology (1)

Question 1

Associated pathologies of these pathologic RBC forms

• Acanthocyte
• Basophilic stippling
• Bite cell
• Elliptocyte
• Macro-ovalocyte
• Ringed sideroblast

Answer 1

• Acanthocyte (spur cell) [A]
  
  • Liver disease, abetalipoproteinemia (states of cholesterol dysregulation).
  • Acantho = spiny.
• Basophilic stippling [B]
  
  • Anemia of Chronic Disease, alcohol abuse, Lead poisoning, Thalassemias.
  • Basically, ACi_D_ alcohol is LeThal.
• Bite cell [C}
  
  • G6PD deficiency.
• Elliptocyte [D]
  
  • Hereditary elliptocytosis.
• Macro-ovalocyte [E]
  
  • Megaloblastic anemia (also hypersegmented PMNs), marrow failure.
• Ringed sideroblast [F]
  
  • Sideroblastic anemia.
  • Excess iron in mitochondria = pathologic.

Question 2

Associated pathologies of these pathologic RBC forms

• Schistocyte
• Sickle cell
• Spherocyte
• Teardrop cell
• Target cell

Answer 2

• Schistocyte (helmet cell) [G]
  
  • DIC, TTP/HUS, traumatic hemolysis (i.e., mechanical heart valve prosthesis).
• Sickle cell [H]
  
  • Sickle cell anemia.
• Spherocyte [I]
  
  • Hereditary spherocytosis, autoimmune hemolysis.
• Teardrop cell [J]
  
  • Bone marrow infiltration (e.g., myelofibrosis).
  • RBC “sheds a tear” because it’s been forced out of its home in the bone marrow.
• Target cell [K]
  
  • HbC disease, Asplenia, Liver disease, Thalassemia.
  • “HALT,” said the hunter to his target.

Question 3

Heinz bodies

• Process
• Associated pathology

Answer 3

• Process
  
  • Oxidation of hemoglobin sulfhydryl groups –>Ž denatured hemoglobin precipitation and phagocytic damage to RBC membrane –>Ž bite cells.
  • Visualized with special stains such as crystal violet.
• Associated pathology
  
  • RBC pathology
  • Seen in G6PD deficiency
  • Heinz body–like inclusions seen in α-thalassemia.

Question 4

Howell-Jolly bodies

• Process
• Associated pathology

Answer 4

• Process
  
  • Basophilic nuclear remnants found in RBCs.
  • Howell-Jolly bodies are normally removed from RBCs by splenic macrophages.
• Associated pathology
  
  • RBC pathology
  • Seen in patients with functional hyposplenia or asplenia.

Question 5

Anemias

• Normocytic

Answer 5

• Normocytic (MCV = 80-100 fL)
  
  • Nonhemolytic (reticulocyte count normal or decreased)
    
    • ACD
      
      • May first present as a normocytic anemia and then progress to a microcytic anemia.
    • Aplastic anemia
    • Iron deficiency (early)
    • Chronic kidney disease
  • Hemolytic (reticulocyte count increased)
    
    • Intrinsic
      
      • Sickle cell anemia
      • HbC defect
      • RBC membrane defect: hereditary spherocytosis
      • RBC enzyme deficiency: G6PD, pyruvate kinase
      • Paroxysmal nocturnal hemoglobinuria
    • Extrinsic
      
      • Autoimmune
      • Infections
      • Microangiopathic
      • Macroangiopathic
  • Normally, you AAIC with SHa_RRP_ AIMM

Question 6

Anemias

• Microcytic
• Macrocytic

Answer 6

• Microcytic (MCV < 80 fL)
  
  • Thalassemias
  • ACD
    
    • May first present as a normocytic anemia and then progress to a microcytic anemia.
  • Iron deficiency (late)
    
    • May first present as a normocytic anemia and then progress to a microcytic anemia.
  • Lead poisoning
  • Sideroblastic anemia
    
    • Copper deficiency can cause a microcytic sideroblastic anemia.
  • Small TAILS
• Macrocytic (MCV > 100 fL)
  
  • Megalobalstic
    
    • Folate deficiency
    • Orotic aciduria
    • B12 deficiency
  • Non-megaloblastic
    
    • Liver disease
    • Alcoholism
    • Reticulocytosis
  • Big FOB LAR

Question 7

Iron deficiency

• Type of condition
• Description
• Findings

Answer 7

• Type of condition
  
  • Microcytic, hypochromic (MCV < 80 fL) anemia
• Description
  
  • Decreased iron due to chronic bleeding (GI loss, menorrhagia), malnutrition/absorption disorders or increased demand (e.g., pregnancy) –>Ž decreased final step in heme synthesis.
• Findings
  
  • Decreased iron, increased TIBC, decreased ferritin.
  • Fatigue, conjunctival pallor [A].
  • Microcytosis and hypochromia [B].
    
    • May manifest as Plummer-Vinson syndrome (triad of iron deficiency anemia, esophageal webs, and atrophic glossitis).

Question 8

α-thalassemia

• Type of condition
• Description
  
  • Defect
  • cis
  • trans
• Findings
  
  • 4 allele deletion
  • 3 allele deletion
  • 1-2 allele deletion

Answer 8

• Type of condition
  
  • Microcytic, hypochromic (MCV < 80 fL) anemia
• Description
  
  • Defect: α-globin gene deletions –>Ž decreased α-globin synthesis.
  • cis deletion prevalent in Asian populations
  • trans deletion prevalent in African populations.
• Findings
  
  • 4 allele deletion:
    
    • No α-globin.
    • Excess γ-globin forms γ4 (Hb Barts).
    • Incompatible with life (causes hydrops fetalis).
  • 3 allele deletion:
    
    • HbH disease.
    • Very little α-globin.
    • Excess β-globin forms β4 (HbH).
  • 1–2 allele deletion:
    
    • No clinically significant anemia.

Question 9

β-thalassemia

• Type of condition
• Description
• Findings
  
  • β-thalassemia minor
  • β-thalassemia major
  • HbS/β-thalassemia heterozygote

Answer 9

• Type of condition
  
  • Microcytic, hypochromic (MCV < 80 fL) anemia
• Description
  
  • Point mutations in splice sites and promoter sequences –>Ž decreased β-globin synthesis.
  • Prevalent in Mediterranean populations.
• Findings
  
  • β-thalassemia minor (heterozygote):
    
    • β chain is underproduced.
    • Usually asymptomatic.
    • ƒƒDiagnosis confirmed by increased HbA2 (> 3.5%) on electrophoresis.
  • β-thalassemia major (homozygote):
    
    • β chain is absent –>Ž severe anemia [C] requiring blood transfusion (2° hemochromatosis).
    • ƒƒMarrow expansion (“crew cut” on skull x-ray) –>Ž skeletal deformities.
      
      • “Chipmunk” facies.
    • Extramedullary hematopoiesis (leads to hepatosplenomegaly).
      
      • Increased risk of parvovirus B19-induced aplastic crisis.
    • Major –>Ž increased HbF (α2γ2).
      
      • HbF is protective in the infant and disease only becomes symptomatic after 6 months.
  • HbS/β-thalassemia heterozygote
    
    • Mild to moderate sickle cell disease depending on amount of β-globin production.

Question 10

Lead poisoning

• Type of condition
• Description
• Findings

Answer 10

• Type of condition
  
  • Microcytic, hypochromic (MCV < 80 fL) anemia
• Description
  
  • Lead inhibits ferrochelatase and ALA dehydratase –>Ž decreased heme synthesis and increased RBC protoporphyrin.
  • Also inhibits rRNA degradation, causing RBCs to retain aggregates of rRNA (basophilic stippling).
  • High risk in old houses with chipped paint.
• Findings
  
  • LEAD:
    
    • Lead Lines on gingivae (Burton lines) and on metaphyses of long bones [D] on x-ray.
    • Encephalopathy and Erythrocyte basophilic stippling.
    • Abdominal colic and sideroblastic Anemia.
    • Drops—wrist and foot drop.
      
      • Dimercaprol and EDTA are 1st line of treatment.
  • Succimer used for chelation for kids
    
    • It “sucks” to be a kid who eats lead.

Question 11

Sideroblastic anemia

• Type of condition
• Description
  
  • Defect
  • Causes
• Findings
• Treatment

Answer 11

• Type of condition
  
  • Microcytic, hypochromic (MCV < 80 fL) anemia
• Description
  
  • Defect in heme synthesis.
    
    • Hereditary: X-linked defect in δ-ALA synthase gene.
  • Causes: genetic, acquired (myelodysplastic syndromes), and reversible (alcohol is most common, lead, vitamin B6 deficiency, copper deficiency, and isoniazid).
• Findings
  
  • Ringed sideroblasts ([E] with iron-laden mitochondria) seen in bone marrow.
  • Increased iron, normal TIBC, increased ferritin.
• Treatment
  
  • Pyridoxine (B6, cofactor for δ-ALA synthase).

Question 12

Megaloblastic anemia

• Type of condition
• Description
• Findings

Answer 12

• Type of condition
  
  • Macrocytic (MCV > 100 fL) anemia
• Description
  
  • Impaired DNA synthesis –>Ž maturation of nucleus of precursor cells in bone marrow delayed relative to maturation of cytoplasm.
• Findings
  
  • Abnormal cell division –>Ž pancytopenia.

Question 13

Folate deficiency

• Type of condition
• Causes
• Findings

Answer 13

• Type of condition
  
  • Megaloblastic macrocytic (MCV > 100 fL) anemia
• Causes
  
  • Malnutrition (e.g., alcoholics), malabsorption, antifolates (e.g., methotrexate, trimethoprim, phenytoin), increased requirement (e.g., hemolytic anemia, pregnancy).
• Findings
  
  • Hypersegmented neutrophils, glossitis, decreased folate, increased homocysteine but normal methylmalonic acid.
  • No neurologic symptoms (distinguishes from B12 deficiency).

Question 14

B12 deficiency (cobalamin)

• Type of condition
• Causes
• Findings

Answer 14

• Type of condition
  
  • Megaloblastic macrocytic (MCV > 100 fL) anemia
• Causes
  
  • Insufficient intake (e.g., strict vegans), malabsorption (e.g., Crohn disease), pernicious anemia, Diphyllobothrium latum (fish tapeworm), proton pump inhibitors.
• Findings
  
  • Hypersegmented neutrophils [A], glossitis, decreased B12, increased homocysteine, increased methylmalonic acid.
  • Neurologic symptoms
    
    • Subacute combined degeneration (due to involvement of B12 in fatty acid pathways and myelin synthesis)
    • Peripheral neuropathy with sensorimotor dysfunction
    • ƒƒDorsal columns (vibration/proprioception)
    • Lateral corticospinal (spasticity)
    • ƒƒDementia

Question 15

Orotic aciduria

• Type of condition
• Description
• Findings

Answer 15

• Type of condition
  
  • Megaloblastic macrocytic (MCV > 100 fL) anemia
• Description
  
  • Inability to convert orotic acid to UMP (de novo pyrimidine synthesis pathway) because of defect in UMP synthase.
  • Autosomal recessive.
  • Presents in children as megaloblastic anemia that cannot be cured by folate or B12 with failure to thrive.
  • No hyperammonemia (vs. ornithine transcarbamylase deficiency— orotic acid with hyperammonemia).
• Findings
  
  • Hypersegmented neutrophils, glossitis, orotic acid in urine.
  • Treatment: uridine monophosphate to bypass mutated enzyme.

Question 16

Nonmegaloblastic anemias

• Type of condition
• Description
• Findings

Answer 16

• Type of condition
  
  • Macrocytic (MCV > 100 fL) anemia
• Description
  
  • Macrocytic anemia in which DNA synthesis is unimpaired.
  • Causes:
    
    • Liver disease
    • Alcoholism
    • Reticulocytosis –>Ž increased MCV
    • Drugs (5-FU, zidovudine, hydroxyurea).
• Findings
  
  • Macrocytosis and bone marrow suppression can occur in the absence of folate/B12 deficiency.

Question 17

Normocytic, normochromic anemia

• Definition
• Intravascular hemolysis
• Extravascular hemolysis

Answer 17

• Definition
  
  • Normocytic, normochromic anemias are classified as nonhemolytic or hemolytic.
  • The hemolytic anemias are further classified according to the cause of the hemolysis (intrinsic vs. extrinsic to the RBC) and by the location of the hemolysis (intravascular vs. extravascular).
• Intravascular hemolysis
  
  • Decreased haptoglobin, increased LDH, schistocytes and increased reticulocytes on peripheral blood smear
  • Urobilinogen in urine (e.g., paroxysmal nocturnal hemoglobinuria, mechanical destruction [aortic stenosis, prosthetic valve], microangiopathic hemolytic anemias).
• Extravascular hemolysis
  
  • Macrophage in spleen clears RBC.
  • Spherocytes in peripheral smear, increased LDH plus increased unconjugated bilirubin, which causes jaundice (e.g., hereditary spherocytosis).

Question 18

Anemia of chronic disease

• Type of condition
• Description
• Findings

Answer 18

• Type of condition
  
  • Nonhemolytic, normocytic anemia
• Description
  
  • Inflammation Ž–> increased hepcidin (released by liver, binds ferroportin on intestinal mucosal cells and macrophages, thus inhibiting iron transport) –> decreased release of iron from macrophages.
• Findings
  
  • Decreased iron, decreased TIBC, increased ferritin.
  • Can become microcytic, hypochromic

Question 19

Aplastic anemia

• Type of condition
• Caused by…
• Findings
• Symptoms
• Treatment

Answer 19

• Type of condition
  
  • Nonhemolytic, normocytic anemia
• Caused by failure or destruction of myeloid stem cells due to:
  
  • Radiation and drugs (benzene, chloramphenicol, alkylating agents, antimetabolites)
  • Viral agents (parvovirus B19, EBV, HIV, HCV)
  • Fanconi anemia (DNA repair defect)
  • Idiopathic (immune mediated, 1° stem cell defect); may follow acute hepatitis
• Findings
  
  • Pancytopenia characterized by severe anemia, leukopenia, and thrombocytopenia.
  • Normal cell morphology, but hypocellular bone marrow with fatty infiltration [A] (dry bone marrow tap).
• Symptoms
  
  • Fatigue, malaise, pallor, purpura, mucosal bleeding, petechiae, infection.
• Treatment
  
  • Withdrawal of offending agent, immunosuppressive regimens (antithymocyte globulin, cyclosporine), allogeneic bone marrow transplantation, RBC and platelet transfusion, G-CSF, or GM-CSF.

Question 20

Chronic kidney disease

• Type of condition
• Findings

Answer 20

• Type of condition
  
  • Nonhemolytic, normocytic anemia
• Findings
  
  • Decreased EPO –>Ž decreased hematopoiesis.

Question 21

Hereditary spherocytosis

• Type of condition
• Description
• Findings
• Labs
• Treatment

Answer 21

• Type of condition
  
  • Extravascular intrinsic hemolytic normocytic anemia
• Description
  
  • Defect in proteins interacting with RBC membrane skeleton and plasma membrane (e.g., ankyrin, band 3, protein 4.2, spectrin).
  • Less membrane causes small and round RBCs with no central pallor (increased MCHC, increased red cell distribution width) –>Ž premature removal of RBCs by spleen.
• Findings
  
  • Splenomegaly, aplastic crisis (parvovirus B19 infection).
• Labs
  
  • Osmotic fragility test (+).
  • Eosin-5-maleimide binding test useful for screening.
  • Normal to decreased MCV with abundance of cells
    
    • Masks microcytia.
• Treatment
  
  • Splenectomy.

Question 22

G6PD deficiency

• Type of condition
• Description
• Findings
• Labs

Answer 22

• Type of condition
  
  • Intravascular/extravascular intrinsic hemolytic normocytic anemia
• Description
  
  • Most common enzymatic disorder of RBCs.
  • X-linked recessive.
  • Defect in G6PD Ž–> decreased glutathione –>Ž increased RBC susceptibility to oxidant stress.
  • Hemolytic anemia following oxidant stress (classic causes: sulfa drugs, antimalarials, infections, fava beans).
• Findings
  
  • Back pain, hemoglobinuria a few days after oxidant stress.
• Labs
  
  • Blood smear shows RBCs with Heinz bodies and bite cells.
• “Stress makes me eat bites of fava beans with Heinz ketchup.”

Question 23

Pyruvate kinase deficiency

• Type of condition
• Description
• Findings

Answer 23

• Type of condition
  
  • Extravascular intrinsic hemolytic normocytic anemia
• Description
  
  • Autosomal recessive.
  • Defect in pyruvate kinase –>Ž decreased ATP –>Ž rigid RBCs.
• Findings
  
  • Hemolytic anemia in a newborn.

Question 24

HbC defect

• Type of condition
• Description
• Findings

Answer 24

• Type of condition
  
  • Extravascular intrinsic hemolytic normocytic anemia
• Description
  
  • Glutamic acid-to-lysine mutation at residue 6 in β-globin.
• Findings
  
  • Patients with HbSC (1 of each mutant gene) have milder disease than have HbSS patients.

Question 25

Paroxysmal nocturnal hemoglobinuria * Type of condition * Description * Findings * Labs * Treatment

Answer 25

* Type of condition * Intravascular intrinsic hemolytic normocytic anemia * Description * Increased complement-mediated RBC lysis (impaired synthesis of GPI anchor for decay-accelerating factor that protects RBC membrane from complement) . * Acquired mutation in a hematopoietic stem cell. * Increased incidence of acute leukemias. * Findings * Triad: Coombs (-) hemolytic anemia, pancytopenia, and venous thrombosis. * Labs * CD55/59 (-) RBCs on flow cytometry. * Treatment * Eculizumab.

Question 26

Sickle cell anemia * Type of condition * Description * Pathogenesis * Findings * Complications in sickle cell disease (SS) * Diagnosis * Treatment

Answer 26

* Type of condition * Extravascular intrinsic hemolytic normocytic anemia * Description * HbS point mutation causes a single amino acid replacement in β chain (substitution of glutamic acid with valine) at position 6. * Newborns are initially asymptomatic because of increased HbF and decreased HbS. * Heterozygotes (sickle cell trait) have resistance to malaria. * 8% of African Americans carry the HbS trait. * Pathogenesis * Low O2, dehydration, or acidosis precipitates sickling (deoxygenated HbS polymerizes), which results in anemia and vaso-occlusive disease. * Findings * Sickled cells are crescent-shaped RBCs [A]. * “Crew cut” on skull x-ray due to marrow expansion from increased erythropoiesis (also in thalassemias). * Complications in sickle cell disease (SS) * Aplastic crisis (due to parvovirus B19). * Autosplenectomy (Howell-Jolly bodies)Ž --\> increased risk of infection with encapsulated organisms * Early splenic dysfunction occurs in childhood. * Splenic sequestration crisis. * Salmonella osteomyelitis. * Painful crisis (vaso-occlusive): dactylitis. (painful hand swelling), acute chest syndrome (most common cause of death in adults), avascular necrosis, stroke. * Renal papillary necrosis (due to low O2 in papilla; also seen in heterozygotes) and microhematuria (medullary infarcts). * Diagnosis * Hemoglobin electrophoresis. * Treatment * Hydroxyurea (increased HbF) and bone marrow transplantation.

Question 27

Autoimmune hemolytic anemia * Type of condition * Description * Warm * Cold * Findings

Answer 27

* Type of condition * Extrinsic hemolytic normocytic anemia * Description * **_Warm_ agglutinin** (Ig**_G_**) * Chronic anemia seen in SLE, CLL, or with certain drugs (e.g., α-methyldopa) * **“_Warm_ weather is **_GGG_**reat”** * **_Cold_ agglutinin** (Ig**_M_**) * Acute anemia triggered by cold * Seen in CLL, Mycoplasma pneumonia infections, or infectious mononucleosis * **“_Cold_ ice cream—yu**_MMM_**”** * Many warm and cold AIHA are idiopathic in etiology. * Findings * Autoimmune hemolytic anemias are usually Coombs (+). * Direct Coombs test * Anti-Ig antibody (Coombs reagent) added to patient’s blood. * RBCs agglutinate if RBCs are coated with Ig. * Indirect Coombs test * Normal RBCs added to patient’s serum. * If serum has anti-RBC surface Ig, RBCs agglutinate when anti-Ig antibodies (Coombs reagent) added.

Question 28

Microangiopathic anemia * Type of condition * Description * Pathogenesis * Findings

Answer 28

* Type of condition * Extrinsic hemolytic normocytic anemia * Description * Seen in DIC, TTP-HUS, SLE, and malignant hypertension. * Pathogenesis * RBCs are damaged when passing through obstructed or narrowed vessel lumina. * Findings * Schistocytes (helmet cells) are seen on blood smear due to mechanical destruction of RBCs.

Question 29

Macroangiopathic anemia * Type of condition * Description * Findings

Answer 29

* Type of condition * Extrinsic hemolytic normocytic anemia * Description * Prosthetic heart valves and aortic stenosis may also cause hemolytic anemia 2° to mechanical destruction. * Findings * Schistocytes on peripheral blood smear.

Question 30

Infections (anemia) * Type of condition * Description

Answer 30

* Type of condition * Extrinsic hemolytic normocytic anemia * Description * Increased destruction of RBCs (e.g., malaria, Babesia).

Question 31

Lab values in anemia * Transferrin * Ferritin * For each (increased/decreased) * Serum iron * Transferrin or TIBC (indirectly measures transferrin) * Ferritin * % transferrin saturation (serum iron/TIBC) * Iron deficiency * Chronic disease * Hemochromatosis * Pregnancy / OCP use

Answer 31

* Transferrin * Transports iron in blood * Ferritin * 1° iron storage protein of body * Iron deficiency * _Serum iron_: Decreased (1°) * _Transferrin or TIBC_: Increased * _Ferritin_: Decreased * _% transferrin saturation_: Really decreased * Chronic disease * _Serum iron_: Decreased * _Transferrin or TIBC_: Decreased * Evolutionary reasoning—pathogens use circulating iron to thrive. * The body has adapted a system in which iron is stored within the cells of the body and prevents pathogens from acquiring circulating iron. * _Ferritin_: Increased (1°) * _% transferrin saturation_: No effect * Hemochromatosis * _Serum iron_: Increased (1°) * _Transferrin or TIBC_: Decreased * _Ferritin_: Increased * _% transferrin saturation_: Really increased * Pregnancy / OCP use * _Serum iron_: No effect * _Transferrin or TIBC_: Increased (1°) * Transferrin production is increased in pregnancy and by OCPs. * _Ferritin_: No effect * _% transferrin saturation_: Decreased

Question 32

Leukopenias * For each * Cell count * Causes * Neutropenia * Lymphopenia * Eosinopenia

Answer 32

* Neutropenia * _Cell count_: Absolute neutrophil count \< 1500 cells/mm3 * _Causes_: Sepsis/postinfection, drugs (including chemotherapy), aplastic anemia, SLE, radiation * Lymphopenia * _Cell count_: Absolute lymphocyte count \< 1500 cells/mm3 (\< 3000 cells/mm³ in children) * _Causes_: HIV, DiGeorge syndrome, SCID, SLE, corticosteroids,a radiation, sepsis, postoperative * Eosinopenia * _Cell count_: N/A * _Causes_: Cushing syndrome, corticosteroids * Corticosteroids don't cause neutrophilia, but eosinopenia and lymphopenia. * Corticosteroids decrease activation of neutrophil adhesion molecules, impairing migration out of the vasculature to sites of inflammation. * In contrast, corticosteroids sequester eosinophils in lymph nodes and cause apoptosis of lymphocytes.

Question 33

Heme synthesis, porphyrias, and lead poisoning (388) * The porphyrias * Lead

Answer 33

* The porphyrias * Hereditary or acquired conditions of defective heme synthesis * Lead to the accumulation of heme precursors. * Lead * Inhibits specific enzymes needed in heme synthesis, leading to a similar condition.

Question 34

Lead poisoning * Affected enzymes * Accumulated substrate * Presenting symptoms

Answer 34

* Affected enzymes * Ferrochelatase * ALA dehydratase * Accumulated substrate * Protoporphyrin, δ-ALA (blood) * Presenting symptoms * Microcytic anemia, GI and kidney disease. * Children—exposure to lead paint--\> Ž mental deterioration. * Adults—environmental exposure (battery/ammunition/radiator factory) --\>Ž headache, memory loss, demyelination.

Question 35

Acute intermittent porphyria * Affected enzyme * Accumulated substrate * Presenting symptoms * Treatment

Answer 35

* Affected enzyme * Porphobilinogen deaminase * Accumulated substrate * Porphobilinogen, δ-ALA, coporphobilinogen (urine) * Presenting symptoms (**5 _P_’s**) * **_P_**ainful abdomen * **_P_**ort wine–colored urine * **_P_**olyneuropathy * **_P_**sychological disturbances * **_P_**recipitated by drugs, alcohol, and starvation * Treatment * Glucose and heme, which inhibit ALA synthase.

Question 36

Porphyria cutanea tarda * Affected enzyme * Accumulated substrate * Presenting symptoms

Answer 36

* Affected enzyme * Uroporphyrinogen decarboxylase * Accumulated substrate * Uroporphyrin (teacolored urine) * Presenting symptoms * Blistering cutaneous photosensitivity [A]. * Most common porphyria.