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USMLE World Missed Questions > Deck XIX > Flashcards

Deck XIX Flashcards

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USMLE® Step 1 flashcards
1
Q

What is extramedullary hematopoiesis?

A

Erythropoietin stimulated, hyperplastic marrow cell invasion of extramedullary organs.

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2
Q

What conditions cause extramedullary hematopoiesis?

A

Severe chronic hemolytic anemias (e.g. b-thalassemia)

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3
Q

What type of arthritis is typically seen in patients with SLE?

A

Symmetric, migratory arthritis.

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4
Q

What antibodies are produced by patients with SLE?

A

Anti ANA (sensitive); anti ds-DNA and anti-SM (specific)

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5
Q

What type of anemia may be present in patients with SLE?

A

Hemolytic anemia, thrombocytopenia, leukopenia.

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6
Q

What are keratins?

A

A broad group of intermediate filaments present in epithelial cells.

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7
Q

What do pathologists use keratin markers to detect?

A

Identification of poorly differentiated tumors or tumors with an unclear site of origin.

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8
Q

Name six types of tumors that stain positive for keratin.

A

Carcinomas, mesotheliomas, thymomas, sarcomas, trophoblastic tumors, desmoplastic small round cell tumors.

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9
Q

Describe the normal hemoglobin composition of adults.

A

HbA (a2b2) = ~97%; HbA2 (a2d2) =~2.5%; HbF (a2y2) = <1%.

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10
Q

What is Hemoglobin HbA1c?

A

A measurement of glycated hemoglobin.

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11
Q

How is Hemoglobin HbA1c formed?

A

Glucose attaches irreversibly to HbA inside erythrocytes by freely diffusing across the RBC membrane. This value reflects average blood glucose levels over the total erythrocyte lifespan.

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12
Q

What states influence HbA1c levels?

A

Changes in RBC survival.

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13
Q

What is the most common form of childhood brain tumor?

A

Pilocytic astrocytoma.

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14
Q

What is the most common location for pilocytic astrocytomas?

A

In the cerebellum of children (but they can develop in the cerebral hemispheres also).

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15
Q

How do pilocytic astrocytomas appear on imaging?

A

As a mass with both solid and cystic components.

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16
Q

How do pilocytic astrocytomas appear on microscopic examination?

A

Pilocytic astrocytes and Rosenthal fibers are seen.

17
Q

What is the most common malignant childhood brain tumor?

A

Medulloblastoma.

18
Q

How do medulloblastomas present on histology?

A

As sheets of small blue cells with hyperchromatic nuclei and scant cytoplasm.

19
Q

Where are medulloblastomas most commonly located?

A

In the cerebellum of children.

20
Q

What is the principle difference between a medulloblastoma and a pilocytic astrocytoma on imaging?

A

A medulloblastoma is a solid tumor; a pilocytic astrocytoma has both cystic and solid components.

21
Q

What is the difference in possible secretory products between small cell carcinoma of the lung vs. squamous cell carcinomas of the lung?

A

Squamous cell produces PTHrP; Small cell produces ACTH and/or vasopressin.

22
Q

Which type of NSAIDs do not impair platelet aggregation?

A

Selective COX2 inhibitors. (Platelets primarily express COX1).

23
Q

What is the function of the Bcl-2 protein?

A

Bcl-2 inhibits apoptosis of tumor cells, promoting survival.

24
Q

Why may excessive bleeding be seen in a patient with significant renal dysfunction?

A

Caused by an accumulation of uremic toxins in circulation which impair platelet aggregation and adhesion/

25
Q

What laboratory characteristics are seen in a patient with abnormal bleeding secondary to renal failure?

A

Qualitative platelet disorder characterized by prolonged bleeding time with normal platelet count, PT, and aPTT. This can be improved with dialysis.

26
Q

What is the characteristic histological appearance of plasma cells?

A

Abundant basophilic cytoplasm, eccentrically placed nuclei, wagon wheel/ clock face distribution of nuclear chromatin.

27
Q

What bone marrow findings are diagnostic of multiple myeloma?

A

Greater than 30% plasma cells.

28
Q

What type of anemia is seen in patients with multiple myeloma?

A

Normocytic and normochromic anemia due to bone marrow infiltration and replacement by malignant plasma cells. Suppression of normal hematopoiesis.

29
Q

What causes osteopenia and bone resorption in a patient with multiple myeloma?

A

Secretion of IL-1 (osteoclast activating factor) and IL-6 by neoplastic cells. This causes hypercalcemia.

30
Q

What forms due to accumulation of monoclonal immunoglobulin light chains in a patient with multiple myeloma?

A

AL amyloid. This contributes to renal failure and amyloidosis of the heart, tongue, and nervous system.

USMLE World Missed Questions (32 decks)

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