Deck XIX Flashcards
What is extramedullary hematopoiesis?
Erythropoietin stimulated, hyperplastic marrow cell invasion of extramedullary organs.
What conditions cause extramedullary hematopoiesis?
Severe chronic hemolytic anemias (e.g. b-thalassemia)
What type of arthritis is typically seen in patients with SLE?
Symmetric, migratory arthritis.
What antibodies are produced by patients with SLE?
Anti ANA (sensitive); anti ds-DNA and anti-SM (specific)
What type of anemia may be present in patients with SLE?
Hemolytic anemia, thrombocytopenia, leukopenia.
What are keratins?
A broad group of intermediate filaments present in epithelial cells.
What do pathologists use keratin markers to detect?
Identification of poorly differentiated tumors or tumors with an unclear site of origin.
Name six types of tumors that stain positive for keratin.
Carcinomas, mesotheliomas, thymomas, sarcomas, trophoblastic tumors, desmoplastic small round cell tumors.
Describe the normal hemoglobin composition of adults.
HbA (a2b2) = ~97%; HbA2 (a2d2) =~2.5%; HbF (a2y2) = <1%.
What is Hemoglobin HbA1c?
A measurement of glycated hemoglobin.
How is Hemoglobin HbA1c formed?
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.
What states influence HbA1c levels?
Changes in RBC survival.
What is the most common form of childhood brain tumor?
Pilocytic astrocytoma.
What is the most common location for pilocytic astrocytomas?
In the cerebellum of children (but they can develop in the cerebral hemispheres also).
How do pilocytic astrocytomas appear on imaging?
As a mass with both solid and cystic components.
How do pilocytic astrocytomas appear on microscopic examination?
Pilocytic astrocytes and Rosenthal fibers are seen.
What is the most common malignant childhood brain tumor?
Medulloblastoma.
How do medulloblastomas present on histology?
As sheets of small blue cells with hyperchromatic nuclei and scant cytoplasm.
Where are medulloblastomas most commonly located?
In the cerebellum of children.
What is the principle difference between a medulloblastoma and a pilocytic astrocytoma on imaging?
A medulloblastoma is a solid tumor; a pilocytic astrocytoma has both cystic and solid components.
What is the difference in possible secretory products between small cell carcinoma of the lung vs. squamous cell carcinomas of the lung?
Squamous cell produces PTHrP; Small cell produces ACTH and/or vasopressin.
Which type of NSAIDs do not impair platelet aggregation?
Selective COX2 inhibitors. (Platelets primarily express COX1).
What is the function of the Bcl-2 protein?
Bcl-2 inhibits apoptosis of tumor cells, promoting survival.
Why may excessive bleeding be seen in a patient with significant renal dysfunction?
Caused by an accumulation of uremic toxins in circulation which impair platelet aggregation and adhesion/
What laboratory characteristics are seen in a patient with abnormal bleeding secondary to renal failure?
Qualitative platelet disorder characterized by prolonged bleeding time with normal platelet count, PT, and aPTT. This can be improved with dialysis.
What is the characteristic histological appearance of plasma cells?
Abundant basophilic cytoplasm, eccentrically placed nuclei, wagon wheel/ clock face distribution of nuclear chromatin.
What bone marrow findings are diagnostic of multiple myeloma?
Greater than 30% plasma cells.
What type of anemia is seen in patients with multiple myeloma?
Normocytic and normochromic anemia due to bone marrow infiltration and replacement by malignant plasma cells. Suppression of normal hematopoiesis.
What causes osteopenia and bone resorption in a patient with multiple myeloma?
Secretion of IL-1 (osteoclast activating factor) and IL-6 by neoplastic cells. This causes hypercalcemia.
What forms due to accumulation of monoclonal immunoglobulin light chains in a patient with multiple myeloma?
AL amyloid. This contributes to renal failure and amyloidosis of the heart, tongue, and nervous system.
