Medical Student SYB

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Medical Student SYB

• December 17, 2008
• Matt Kulzer MSIV

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Case Overview

• History
• 14yo male with history of Ataxia-Telangiectasia
• Presented yesterday with 3 wk h/o chest pain,
  headache, low grade fever, and fatigue
• Physical Exam
• T 38.1, HR 106, RR 20, SpO2 99 on RA
• Remainder WNL
• Labs
• Omitted

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Additional Information/Findings

• WBC 249,000
• Anemia/thrombocytopenia
• Smear
• Preponderance of blasts
• CXR - Soft tissue density projecting along the
  right heart border on the AP view. It appears to
  be contiguous with the heart border, and there is
  no evidence of a posterior mediastinal mass on
  the lateral view. This could represent a
  mediastinal mass rather than prominent ascending
  aorta. The former is more likely given high WBC
  and concern for leukemia. Recommend comparison
  to any outside chest radiographs before
  proceeding to additional cross-sectional imaging
  studies.
• CT
• Heterogeneous anterior mediastinal mass measuring
  4.2 x 6 cm in shortest and long axis. This
  anterior mediastinal mass abutting the right
  atrium, right ventricle, SVC, and descending
  aorta.
• Two adjacent nodular opacities within the
  posterior basal segment of the right lower lobe,
  that are concerning for leukemic infiltrates or
  metastatic lesions versus infectious process (in
  a patient with history of fever).
• Marked splenomegaly.

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Ataxia Telangiectasia

• AR hereditary ataxic disorder
• Patients develop
• progressive cerebellar ataxia
• abnormal eye movement
• other neurologic disorders (gross motor dysfxn,
  LMN weakness, speech/swallowing dysfnx)
• oculocutaneous telangiectasias
• immune deficiency
• leukemias/lymphomas

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Mechanism of DNA damage susceptibility in AT

• Interaction between cancer susceptibility genes
  and DNA repair. ATM (ataxia-telangiectasia
  mutated) senses a double-strand break in DNA,
  induced by agents such as ionizing radiation. ATM
  and CHEK2 phosphorylate BRCA1, promoting its
  migration to the break site. The Fanconi's anemia
  protein complex (proteins A, C, E, F, G) triggers
  the ubiquitination and co-localization of the
  Fanconi protein D2 with BRCA1 at the break site.
  BRCA2 carries RAD51, an enzyme involved in DNA
  recombination repair, to the same site. BRCA1,
  BRCA2, and RAD51 repair the DNA break by an
  error-free recombination mechanism. RAD51 is a
  component of cell cycle check points. (Redrawn
  from Venkitaraman AR A growing network of
  cancer-susceptibility genes. N Engl J Med
  3481917, 2003 and taken from Robbins and Cotran
  Pathologic Basis of Disease 7E on December 16,
  2008.)

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Mediastinal Masses Approach

• Identify the lesion
• Location
• AP
• LATERAL!!!!
• Know the differentials based on location/age of pt

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Mediastinal Masses Anatomy
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Mediastinal Masses Anterior

• Anterior Mediastinal Masses DDx
• Thymic Masses
• Lymphoma
• Thymoma
• Thymic ca
• Thymolipoma
• Thymic cyst
• Thymic hyperplasia
• Thyroid Masses
• Thyroid goiter
• Thyroid cyst
• Thyroid adenoma
• Thyroid ca
• Germ Cell Tumors
• Teratoma/teratocarcinoma
• Seminoma
• Mixed Germ cell tumors
• indicates most common

• Or, simplified
• The 4 Ts
• Thymoma
• Thyroid lesions
• Teratoma
• T-cell lymphoma

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Mediastinal Masses Middle

• Middle Mediastinal Masses DDx
• Goiter
• Lymphadenopathy
• Mets(lung ca most common)
• Lymphoma/leukemia
• Granulomatous infection
• Sarcoidosis
• Inhalational lung disease (i.e., silicosis,
  berylliosis, coal workers pneumoconiosis)
• Castlemans disease
• Aortic abnormalities aneurysm, dissection,
  traumatic rupture
• Bronchopulmonary foregut cysts
• Tracheal tumor
• Esophageal abnormalities neoplasm, achalasia
• Hiatal hernia (with air/fluid level)
• Cardiac tumor
• Left ventricle aneurysm/pseudoaneurysm
• Pulmonary artery aneurysm
• Neurogenic tumor of vagus nerve
• indicates most common

• Or Simplified
• Thoracic aortic aneurysms
• Hematomas
• Neoplasms
• Adenopathy
• Esophageal lesions
• Diaphragmatic hernias
• Duplication cysts

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Mediastinal Masses Posterior

• Posterior Mediastinal Masses DDx
• Neurogenic tumors (peripheral nerve, sympathetic
  ganglion, parasympathetic involvement)
• Primary or metastatic bone tumor of thoracic
  spine
• Osteomyelitis or paraspinal abscess of thoracic
  spine
• Extramedullary hematopoesis
• indicates most common

• Or simply
• 90 Neurogenic
• Young neuroblastoma
• Adult neurofibromas, schwannomas,
  ganglioneuromas
• Others
• Hernias
• Other neoplasms
• Hematomas
• Extramedullary hematopoesis

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References

• Kumar, et al (2005). Molecular Basis of Cancer,
  Robbins and Cotran Pathologic Basis of Disease
  7E. Philadelphia Elsevier
• Mettler, FA (2005). Mediastinal Masses,
  Essentials of Radiology. Philadelphia Elsevier
• Puneet, et al (2008). Ataxia-telangiectasia, Up
  To Date. Retrieved from http//www.utdol.com.proxy
  1.athensams.net/online/content/topic.do?topicKeyp
  ed_neur/9337selectedTitle1150sourcesearch_res
  ult
• Torrigan, DA and Wallace, TM (2006). Mediastinal
  Masses. Pretorius, ES and Solomon, JA (Eds.),
  Radiology Secrets Second Ed.). Philadelphia
  Elsevier.