Cardio USMLE 9-27 (3) Flashcards
This 30-year-old woman presents with severe knee pain and a tender effusion on the knee. Based on the patient’s age and gender, as well as the location of the tumor, she most likely has a giant cell tumor. The appearance of the tumor—with a nonsclerotic and sharply defined border—is also a clue that this is a?
giant cell tumor.
Giant cell tumors are primary bone tumors that most commonly occur at the epiphyseal end of long bones. They are benign, but locally aggressive tumors occurring most frequently at the distal femur or proximal tibia. Giant cell tumors have a peak incidence in people from age 20 to 40 years old. They tend to occur more often in women.
On radiography, giant cell tumors generally appear as “soap bubble” lytic lesions next to a joint. They are distinguishable from other bony tumors on xX-ray, since they appear to have a nonsclerotic and sharply defined border. Giant cell tumors are typically composed of oval mononuclear cells along with scattered multinucleated giant
Chondrosarcoma more commonly affects the axial skeleton. Ewing sarcoma classically shows onion-skinning on x-ray, and primarily affects younger boys. Osteochondromas affect ?
the metaphysis of long bones. Osteosarcoma is more common in younger males and shows periosteal shadowing (Codman triangle) on x-ray.
Giant cell tumors most frequently occur at the epiphyseal end of long bones and most commonly in women age 20–40 years old. The classic radiologic findings are?
“soap bubble” lesions at the epiphyses of long bones.
This patient with pearly white/skin-colored papules with central umbilication has the classic dermatological finding associated with molluscum contagiosum. Caused by a poxvirus, an ?
enveloped virus with double-stranded, linear DNA, molluscum contagiosum virus is most frequently seen in children. In this population, the virus is often transmitted through skin-to-skin contact or indirect contact with fomites (e.g. gymnasium equipment). Lesions commonly occur on the chest, arms, trunk, legs, face, and intertriginous areas.
Molluscum contagiosum also occurs in adults and may be transmitted sexually. In such cases, if the patient is immunocompetent, lesions tend to be located around the genitalia and surrounding areas, as seen in this patient. Widespread, persistent, and atypical presentations may be seen in immunocompromised patients. The infection often resolves spontaneously, but may require topical therapy or surgery in immunocompromised patients.
The organisms named in the alternate answer choices do not produce the pearly white or skin-colored papules with central umbilication seen in this patient’s skin. Among the non-enveloped RNA viruses, coxsackie virus, which causes hand, foot, and mouth disease, is most closely associated with a rash; however, this is described as red, blister-like lesions. Microsporum, a mold, (and several similar organisms) cause cutaneous infections with a pruritic, flat rash on several parts of the body. Malassezia species, al-shaped, budding yeasts, are responsible for tinea versicolor, an infection in which patches of skin become discolored due to?
melanocyte damage by the infecting fungus. Rickettsia are gram-negative, obligate intracellular bacteria capable of causing a rash, which is erythematous; other similar organisms also cause rashes different from those in the illustration. Infections caused by this pathogen often present with systemic symptoms, as well. Dermatological findings of Treponema pallidum, a spiral-shaped bacterium, include maculopapular rashes, characterized by flat, coarse red areas of skin; other spirochetes also cause rashes.
Molluscum contagiosum manifests as white or skin-colored papules or nodules with?
central umbilication. It often resolves spontaneously.
The woman has signs of fever, dyspnea, hypotension, and widespread coagulopathy such as oozing IV sites and uncontrollable vaginal bleeding. The inadequate hemostasis should raise suspicion for disseminated intravascular coagulation (DIC), likely secondary to an amniotic fluid embolism that traveled to her pulmonary circulation. Common causes of DIC are gram-negative sepsis, malignancy, pancreatitis, trauma, transfusion reactions, and obstetric complications such as amniotic fluid embolism.
In DIC, there is a massive activation of the coagulation cascade that results in thrombus formation throughout the microvasculature. This results in rapid consumption of both platelets and coagulation factors. Concurrent with this consumption coagulopathy is activation of the fibrinolytic system, which results in elevated fibrin degradation products (FDPs). Ultimately, complications in DIC result from thrombosis and bleeding and include massive blood loss and organ failure. Laboratory findings include?
a decreased platelet count, elevated bleeding time, elevated prothrombin time, elevated partial thromboplastin time, and elevated D-dimer.
DIC may be caused by sepsis, malignancy, and obstetric complications. The resultant consumption coagulopathy leads to?
laboratory findings of a decreased platelet count, elevated bleeding time, elevated prothrombin time, elevated partial thromboplastin time, and elevated fibrin split products.
This asymptomatic patient presents for a routine physical exam and has a mildly decreased hemoglobin. Because the MCV is decreased, it is considered a microcytic anemia. The two most common causes of microcytic anemia are iron deficiency anemia and thalassemia. Definitive diagnosis of either disease requires iron studies and a hemoglobin electrophoresis. However, a presumptive diagnosis can be made by reviewing the remaining CBC indices.
This patient’s RBC is increased, and his red cell distribution width (RDW) is normal, both of which are consistent with?
thalassemia and inconsistent with iron-deficiency anemia. In mild cases of thalassemia, the RBC is actually increased, which is unusual for an anemia (in iron-deficiency anemia, for example, the RBC is decreased). The RDW is a measure of how much variation in size there is in the patient’s red cells. In mild thalassemia, the red cells are all similar in size, meaning the RDW is normal. In iron-deficiency anemia, the red cells get smaller and smaller as the iron deficiency progresses, resulting in an RDW which is increased.
This patient’s Tunisian ethnicity is also consistent with ß-thalassemia, which is more common in individuals from countries around the Mediterranean, North Africa, the Indian subcontinent, and Eastern Europe.
A common morphologic finding in thalassemia is target cells (red cells with a condensation of hemoglobin in the center, giving them a target appearance). Several target cells can be seen in the image above.
Helmet-shaped red cells are seen in disseminated intravascular coagulation (DIC). The blood in DIC shows a microangiopathic hemolytic anemia, characterized by schistocytes (fragmented red cells, such as helmet cells).
Neutrophils with an increased number of nuclear lobes (or hypersegmented neutrophils) are indicative of megaloblastic anemia, a macrocytic anemia due to decreased B12 and/or folate.
Crescent-shaped red cells are seen in ?
sickle cell anemia, a genetic disorder in which a point mutation in the beta globin chain causes hemoglobin polymerization (and sickle cell formation) at low oxygen tension. Sickle cell anemia is typically normocytic (the MCV is usually within the normal range), and the RBC is normal to decreased. The RDW is increased during sickle cell crises due to the variation in cell size.
RBCs lacking central pallor (spherocytes) are seen in hemolytic anemias and in hereditary spherocytosis, which are normocytic anemias.
Mild thalassemia typically presents as a microcytic anemia, with two characteristic CBC findings: an increased RBC and a normal RDW. Target cells are frequently present in?
the blood smear, although they are seen in other disorders as well.
Certain changes in a pregnant woman’s thyroid hormone levels can be anticipated. Due in part to rising estrogen levels, there is an increase in hepatic synthesis of thyroxine-binding globulin (TBG). The total amount of thyroid hormone in the body (represented by total T4 ) subsequently increases with the rise in TBG. During a normal pregnancy, the level of unbound, active thyroid hormone (represented as free T4 ) typically remains unchanged due to normal negative feedback processes. As such, this patient will have to take increased levels of her thyroid hormone to counteract the elevated TBG. However, a pregnant woman with no history of thyroid disease will be clinically ?
euthyroid despite her elevated levels of TBG and total T4.
In a healthy pregnancy neither thyroid-binding globulin nor total T4 decreases; this patient shows no signs of the hypothyroidism that would be associated with these changes, such as constipation and cold intolerance. In addition, she does not present with levels that suggest anorexia or chronic liver disease, low TBG, decreased total T4, and unchanged free T4. Increased estrogen causes TBG to increase. An increase in Free T4 would indicate hyperthyroidism, a complication that occurs in 1 out of 1000–2000 pregnant women and is commonly caused by Graves disease.
PregnantEstrogenGlobulinRisePregnancyEuthyroidHypothyroidismConstipation
During a normal pregnancy, there is an increase in?
total thyroxine and thyroxine-binding globulin, but the amount of metabolically active free or unbound thyroxine (T4) remains unchanged due to normal negative feedback processes. Consequently, pregnant women typically remain euthyroid.
This patient with painful ulcerated skin lesions and a history of abdominal pain and intermittent diarrhea most likely has Crohn disease with pyoderma gangrenosum. The diagnosis of Crohn disease is confirmed by skip lesions with edematous (cobblestone) mucosa on colonoscopy. It is not uncommon for a dermatologic manifestation of an underlying disorder to be the chief complaint of a patient with inflammatory bowel disease (IBD). Other extraintestinal manifestations include migratory arthritis, sacroiliitis, ankylosing spondylitis, erythema nodosum, uveitis, and primary sclerosing cholangitis (most common with ulcerative colitis). This patient’s pyoderma gangrenosum would be best addressed by ?
administration of oral corticosteroids to treat the underlying Crohn disease.
The other medication choices would not be effective against pyoderma gangrenosum, because they would not address the patient’s underlying IBD. Ampicillin, bacitracin, and tetracycline would be better suited to treating bacterial infections such as cellulitis or necrotizing fasciitis. Glipizide would be useful in controlling blood sugar in a patient with diabetes and a diabetic foot ulcer.
Extraintestinal manifestations of inflammatory bowel disease (IBD) include skin lesions such as pyoderma gangrenosum. Treatment of such manifestations consists of treating the underlying IBD with?
oral corticosteroids.
