A 17-year-old boy is brought to the emergency department due to cough and difficulty breathing. He first developed a nighttime cough about 3 weeks ago. The cough has progressed, now occurring throughout the day. For the past couple of days, the patient has felt fatigued during routine activities. He has no known chronic medical conditions and takes no medications aside from an over-the-counter cough medicine, which has not helped. Temperature is 37.2 C (99 F), blood pressure is 100/60 mm Hg, pulse is 110/min, and respirations are 30/min. Lung examination shows diminished breath sounds bilaterally in the anterior chest with no wheezing or crackles. Cardiac examination reveals tachycardia without murmurs. The neck is supple with distension of the jugular veins. Abdominal examination shows hepatosplenomegaly, and there is also nontender enlargement of the left testicle. Skin examination shows pallor. Complete blood count results are as follows: Chest radiograph shows a large anterior mediastinal mass. Which of the following is the most likely diagnosis in this patient?

Question

A 17-year-old boy is brought to the emergency department due to cough and difficulty breathing.  He first developed a nighttime cough about 3 weeks ago.  The cough has progressed, now occurring throughout the day.  For the past couple of days, the patient has felt fatigued during routine activities.  He has no known chronic medical conditions and takes no medications aside from an over-the-counter cough medicine, which has not helped.  Temperature is 37.2 C (99 F), blood pressure is 100/60 mm Hg, pulse is 110/min, and respirations are 30/min.  Lung examination shows diminished breath sounds bilaterally in the anterior chest with no wheezing or crackles.  Cardiac examination reveals tachycardia without murmurs.  The neck is supple with distension of the jugular veins.  Abdominal examination shows hepatosplenomegaly, and there is also nontender enlargement of the left testicle.  Skin examination shows pallor.  Complete blood count results are as follows:  Chest radiograph shows a large anterior mediastinal mass.  Which of the following is the most likely diagnosis in this patient?

Quizplus · Accepted Answer

11ec25c8_d692_6d46_bc81_eb3540f3a9a1_MD0003_00 This adolescent has an anterior mediastinal mass with associated superior vena cava (SVC) syndrome, a condition in which SVC obstruction leads to venous swelling of the head and neck (eg, jugular venous distension), as well as laryngeal edema (eg, cough, difficulty breathing). In the setting of pancytopenia and testicular enlargement, these findings are worrisome for acute lymphoblastic leukemia (ALL) . superior vena cava (SVC) syndrome Although most common in young children, ALL in adolescents and young adults is often associated with a mass of thymic origin (eg, anterior mediastinal mass) that causes compressive symptoms. Extramedullary leukemic spread commonly results in hepatosplenomegaly and may cause nontender, testicular enlargement, as seen here. In addition, classic findings of bone marrow failure may be present and include fatigue/pallor from anemia, bruising caused by thrombocytopenia, or recurrent infections due to neutropenia; however, white blood cell count is often variable because leukocytosis can occur once leukemic cells overcrowd the bone marrow and spill into the periphery. Diagnosis of ALL is confirmed by abnormally increased lymphoblasts (>20%) on bone marrow aspirate. In the case of a mediastinal mass, flow cytometry of the bone marrow aspirate usually reveals T lymphoblasts as the cells of origin due to their proliferation within the thymus during lymphocyte maturation. (Choice B) Acute myeloid leukemia (AML) can present with hepatosplenomegaly and pancytopenia. However, compared to AML, ALL is a much more likely diagnosis in children. In addition, mediastinal involvement with subsequent SVC syndrome would be unusual in AML because the thymus is the site of T lymphocyte (rather than myeloid cell) proliferation; and testicular enlargement is not typical of AML. (Choice C) Burkitt lymphoma is a neoplasm of mature B cells associated with Epstein-Barr virus infection and typically affects children. Although pancytopenia and hepatosplenomegaly can occur, patients typically have a mass involving the mandible or abdominal viscera; mediastinal involvement is rare. (Choice D) Chronic lymphocytic leukemia can present with hepatosplenomegaly, anemia, and thrombocytopenia, but patients are usually older adults (median age 70) and have lymphocytosis. This patient's age, mediastinal mass, and leukocyte count are inconsistent with this diagnosis. (Choice E) Thymoma is a common cause of a mediastinal mass that can cause obstructive symptoms but typically occurs in patients age >40, making this diagnosis unlikely. Moreover, testicular examination would be normal, and pancytopenia would not be expected. Educational objective: Acute lymphoblastic leukemia should be considered in an adolescent patient with an anterior mediastinal mass in addition to pancytopenia, hepatosplenomegaly, and testicular enlargement. Presentation often relates to compression of mediastinal structures, such as superior vena cava syndrome causing jugular venous distension and difficulty breathing/cough. References: Biology of childhood acute lymphoblastic leukemia. (http://www.ncbi.nlm.nih.gov/pubmed/25435111)

A 17-Year-Old Boy Is Brought to the Emergency Department Due