USMLE USMLE Certifications USMLE-STEP-1 Questions & Answers

• Question 291:

  A 56-year-old woman returns to clinic for a follow-up after undergoing a lung biopsy of a 1.4 ?2.1 cm, left upper lobe lesion originally discovered on chest x-ray. Her physician checks her record for the pathology report and reads that histology of the biopsy demonstrated "scattered spindle cells with a minimal mononuclear inflammatory infiltrate and few blood vessels in a background of abundant pale connective tissue. Small areas of calcification are observed and there is no evidence of normal lung parenchyma." Which of the following is most likely responsible for these findings?

  A. deposition of amyloid protein

  B. hamartoma formation

  C. healing of an abscess

  D. malignant transformation of type 1 pneumocytes

  E. unresolved infection with Mycobacterium tuberculosis

  Correct Answer: C

  Section: Pathology and Path physiology The first sentence of the pathology report describes the histological morphology of granulation tissue, representing evidence of healing within the biopsied lesion. The absence of normal lung parenchyma indicates that injury to the lung was extensive enough to prohibit regeneration, and this would be expected due to the liquefactive necrosis occurring with abscess formation. Areas of calcification can develop in any necrotic tissue and represent a nonspecific finding. Deposition of amyloid protein (choice A), or amyloidosis, is associated with particular chronic diseases (AA protein) or certain immunoglobulinsecreting neoplasms (AL protein). It appears histologically as extracellular, diffusely distributed, acellular material and is best demonstrated using Congo-red stain. The pathology report was not consistent with the morphology of a hamartoma (choice B), which refers to a disorganized mass of mature tissue indigenous to the organ in which it arises. There was also no cytological description suggestive of malignancy (choice D, malignant transformation of type 1 pneumocytes), such as pleomorphism or hyperchromatism. Granulation tissue could potentially be seen in an unresolved infection with M. tuberculosis (choice E); however, evidence of granuloma formation is necessary to establish the diagnosis.

• Question 292:

  A 67-year-old woman notices a lump in her left supraclavicular area. The lesion is excised and a section of it is shown in below figure. The microscopic appearance is most consistent with which of the following diagnoses?

  

  A. adenocarcinoma

  B. carcinoid

  C. fibroadenoma

  D. fibrosarcoma

  E. malignant fibrous histiocytoma

  Correct Answer: A

  Section: Pathology and Path physiology The finding of an enlarged left supraclavicular lymph node (Virchow or signal node) should raise the question of an underlying GI malignancy. This is confirmed in the above case by the microscopic findings in figure. The pleomorphism of these cells and the fact that they are located in a lymph node indicate that these are malignant cells. Additionally, the glandular appearance identifies this as an adenocarcinoma metastatic to a lymph node. Carcinoid tumors (choice B) arise from neuroendocrine cells present in the mucosa throughout the GI tract. About 40% are found in the appendix, where they are benign in 99% of cases. Another 25% are found in the ileum. Of these, about 60% are malignant. If they metastasize to the liver, they can give rise to the carcinoid syndrome. Fibroadenoma (choice C) is the most common benign tumor of the female breast. Fibrosarcoma (choice D) and malignant fibrous histiocytoma (choice E) are both fibroblastic sarcomas; the photomicrograph clearly indicates a malignancy of epithelial (glandular) origin.

• Question 293:

  A 29-year-old male AIDS patient presents with discrete and confluent white plaques adherent to the oral and pharyngeal mucosa. Microscopic examination of these plaques would most likely reveal which of he following?

  A. broad nonseptate mold with right angle branching

  B. encapsulated yeast with narrow-based budding

  C. narrow septate mold with acute angle branching

  D. pseudohyphae with yeast-like forms

  E. unencapsulated yeast with broad-based budding

  Correct Answer: D

  Section: Pathology and Path physiology Candida is the most common fungal infection in AIDS patients and most frequently involves the oral cavity and esophagus; the clinical appearance is typically as described. Microscopically, Candida is composed of pseudohyphae with some yeast-like forms. Choices A, B, C, and E are, respectively, the microscopic appearances of Mucor, Cryptococcus, Aspergillus, and Blastomyces.

• Question 294:

  A 58-year-old man has a 5-year history of progressively worsening heart failure. An autopsy limited to the heart reveals extensive replacement of the myocardium by an acellular eosinophilic material. This material is most likely to be which of the following?

  A. amyloid

  B. calcium salt deposition

  C. cholesterol

  D. myocyte fibrinoid necrosis

  E. postinfarctive cicatrix

  Correct Answer: A

  Section: Pathology and Path physiology Amyloid is an acellular material that is eosinophilic. After Congo-red staining, there is apple-green dichroism when examined under polarized light microscopy. Calcium salts (choice B) tend to be deeply basophilic, not eosinophilic, with routine stains. Cholesterol deposits (choice C) tend to dissolve out of tissues with routine processing agents and only empty outlines of where the crystals once were are present remain. Myocyte fibrinoid necrosis (choice D) would be moderately cellular and eosinophilic. Congo-red dichroism is not evident. A postinfarctive cicatrix (choice E) also displays a relatively acellular eosinophilic morphology. Congo-red staining would not be dichroic, however.

• Question 295:

  A 26-year-old woman complains of the acute onset of anuria, purpura, and mental confusion. Her peripheral blood film displays marked thrombocytopenia and abundant schistocytes. Laboratory studies reveal elevations of bilirubin, creatinine, and lactose dehydrogenase. A skin biopsy shows numerous intravascular thrombi within the dermal microvasculature. What is the most likely diagnosis?

  A. acute idiopathic thrombocytopenia purpura

  B. BernardSoulier syndrome

  C. Glanzmann thrombasthenia

  D. MayHegglin anomaly

  E. thrombotic thrombocytopenic purpura

  Correct Answer: E

  Section: Pathology and Path physiology Thrombotic thrombocytopenic purpura is an acute microangiopathic hemolytic anemia. The clinical picture usually includes mental alterations, anuria, mucosal bleeding, and purpura. An abnormal platelet-aggregating substance is the likely initiating event. Acute idiopathic thrombocytopenia (choice A) does not have a hemolytic component, lacks renal failure, and does not display thrombi in the skin biopsy. Bernard-Soulier syndrome (choice B) and Glanzmann thrombasthenia (choice C) are hereditary disorders of platelet aggregation. Clinical symptoms of a coagulopathy usually occur in infancy. MayHegglin anomaly (choice D) is an inherited condition with thrombocytopenia and morphologically abnormal WBCs. Hemolysis, acute onset, and mental aberrations do not typify this disorder.

• Question 296:

  A 51-year-old alcoholic man is admitted to the emergency room with a 6-hour history of severe epigastric pain that radiates to his back and is more intense in a supine position. Physical examination reveals tachycardia, hypotension, and low-grade fever consistent with the early stage of shock. Which of the following serum measurements would be most useful in providing a diagnosis of his condition?

  A. amylase

  B. aspartate aminotransferase

  C. bilirubin

  D. calcium E. troponin I

  Correct Answer: A

  Section: Pathology and Path physiology The hallmark of acute pancreatitis is abdominal pain that is initially localized to the epigastrium and later becomes diffuse. It typically radiates to the back and is frequently more intense in the supine position. Other common symptoms and signs include nausea, vomiting, and tachycardia. If the pancreatitis is severe, hypotension can occur due to extravasation of blood and fluids into peritoneal (third) spaces and shock may ensue. Measurement of both amylase and lipase enzyme levels are useful in the diagnosis of acute pancreatitis. Amylase levels rise early in the course of the disease, while elevation of lipase levels may not occur until 24 hours after onset of illness. Although false positives and false negatives do occur, an elevated amylase level in conjunction with a consistent pattern of acute epigastric/abdominal pain is considered evidence of acute pancreatitis if other acute surgical conditions have been ruled out. Aspartate aminotransferase (choice B) is produced by a number of tissues and is increased in a variety of diseases; however, its greatest value is in liver function testing. Bilirubin (choice C) may be increased in an alcoholic but has no value in the diagnosis of acute pancreatitis. Calcium soap formation in the areas of fat necrosis may lead to a decrease in serum calcium (choice D) levels, but this is considered to be a nonspecific test. Troponin I (choice E) is now the preferred serum marker for the diagnosis of MI and has no role in the diagnosis of acute pancreatitis.

• Question 297:

  A 66-year-old woman with a 3-year history of right hip pain undergoes a prosthetic hipreplacement. A photograph of her diseased femoral head is displayed in below figure. What is the likely cause of this abnormality?

  

  A. benign neoplastic process

  B. coagulopathy

  C. degenerative process

  D. infection

  E. malignant neoplastic process

  Correct Answer: C

  Section: Pathology and Path physiology The femoral head shows marked degenerative osteoarthritis. The gradual destruction of articular cartilage can eventually lead to joint compromise through eburnation, osteophyte formation, subchondral cysts, and osteochondral loose body formation. Clinically, these anatomic changes are reflected as joint pain and a restricted range of motion. Figure does not display evidence of a benign neoplasm (choice A), coagulopathy (choice B), infection (choice D), or malignant neoplastic process (choice E).

• Question 298:

  A 71-year-old woman suffers severe head injuries in a mugging and is hospitalized in a comatose state. While in the hospital, she develops severe pneumonia and on day 11 goes into cardiac arrest and cannot be resuscitated. At autopsy she is found to have advanced coronary atherosclerosis and a pulmonary embolism judged to have occurred within the past 23 days. The coroner should list which of the following on the death certificate as the underlying (or proximate) cause of death?

  A. atherosclerosis

  B. blunt trauma to the head GI

  C. cardiopulmonary arrest

  D. pneumonia

  E. pulmonary embolism

  Correct Answer: B

  Section: Pathology and Path physiology The proximate or underlying cause of death is the initiating event that led to the person's death and is what should be listed on the death certificate as the cause of death. In this case, if the woman had not been struck on the head she would not have been hospitalized, not contracted a nosocomial pneumonia (choice D), not had a pulmonary embolism due to the prolonged immobilization (choice E), and not had a cardiopulmonary arrest (choice C). Atherosclerosis (choice A) must have been present for many years prior to the mugging and had no role in her death.

• Question 299:

  A 43-year-old woman with a long history of chronic allergies visits her primary care physician with a 2week history of progressive left perinasal pain and nasal pressure, increasing episodes of yellowish- green nasal discharge, and a fever 1 day prior of 100.8癋. Sign ificant findings on physical examination include a temperature of 101.0癋, tenderness to palpation ove r the left maxillary sinus, and nasal speculum observation of obstruction of the left middle meatus by a large, pale, polypoid mass with a small focus of ulceration and a similar but smaller mass seen in the right middle meatus. A clinical diagnosis of left maxillary sinusitis is made and the patient is started on antibiotics. She is subsequently referred to an otolaryngologist who excises the bilateral masses to relieve the sinus obstruction. Which of the following findings would you expect the pathologist to see on microscopic examination of these masses?

  A. hyperkeratotic squamous epithelium with a submucosal core of myxoid connective tissue, frequent blood vessels, mild fibrosis, and a mononuclear infiltrate

  B. myofibroblastic proliferation in a dense fibrovascular stroma with numerous endothelial-lined channels

  C. papillomatous proliferation of squamous epithelium extending downward through the submucosal connective tissue

  D. respiratory epithelium containing an edematous, loose stroma and a mixed inflammatory infiltrate, with a prominence of neutrophils and eosinophils

  E. undifferentiated large epithelial cells with round vesicular nuclei and prominent nucleoli in a syncytial arrangement with a marked lymphocytic infiltration

  Correct Answer: D

  Section: Pathology and Path physiology Given the history of allergies and the finding of bilateral polypoid masses, it is most likely that this patient has nasal polyps, the typical histology of which is as described. Hyperkeratotic squamous epithelium with a submucosal core of myxoid connective tissue, frequent blood vessels, mild fibrosis, and a mononuclear infiltrate (choice A) is the histological description of a vocal cord polyp. Myofibroblastic proliferation in a dense fibrovascular stroma with numerous endothelial-lined channels (choice B) describes the histology of a nasopharyngeal angiofibroma. Papillomatous proliferation of quamous epithelium extending downward through the submucosal connective tissue (choice C) refers to an inverted papilloma. An undifferentiated large epithelial cells with round vesicular nuclei and prominent nucleoli in a syncytial arrangement with a marked lymphocytic infiltration (choice E) is the histological description of an undifferentiated nasopharyngeal carcinoma.

• Question 300:

  A 39-year-old woman reports headaches, weakness and fatigue, and frequent urination over the past several weeks. Physical examination reveals diastolic hypertension. Laboratory findings include hypokalemia and reduced rennin levels. Which of the following is the most likely cause of these various findings?

  A. Conn syndrome

  B. diabetes insipidus

  C. diabetes mellitus

  D. pheochromocytoma

  E. polycystic renal disease

  Correct Answer: A

  Section: Pathology and Path physiology Primary aldosteronism caused by an aldosterone-secreting adrenal neoplasm is known as Conn syndrome. Excess aldosterone production leads to increased sodium retention and reciprocal potassium depletion in the renal distal tubule; polyuria results from impairment in urinary concentrating ability. Increased sodium reabsorption and associated extracellular fluid expansion lead to diastolic hypertension and suppression of the reninangiotensin pathway. Muscle weakness and fatigue are a consequence of hypokalemia, which may be severe in some cases. Diabetes insipidus (choice B) is marked by the fairly sudden onset of extreme polyuria and (for the central type) is due to decreased activity of antidiuretic hormone typically associated with an intracranial lesion or trauma. In diabetes mellitus (choice C), glucose levels exceed renal reabsorption capacity, leading to glycosuria and a consequent osmotic diuresis, hypovolemia, and pseudohyponatremia. Pheochromocytomas (choice D) are unilateral, solitary neoplasms most commonly arising from chromaffin cells in the adrenal medulla. Although biologically benign, excessive secretion of catecholamines causes paroxysmal systolic and diastolic hypertension that may reach life-threatening pressures. The adult form of polycystic renal disease (choice E) is an autosomaldominant condition characterized by grossly enlarged bilateral kidneys containing numerous, and variably-sized expansile cysts. Hematuria, pyelonephritis, hypertension, and polyuria are common symptoms.