Read first the text book: Computed Tomography and Magnetic resonance of the Thorax by Nadich et all

Then go through this exercise to assess your comprehension

Mediastinal Lymph nodes

• 80% of nodes are adjacent to tracheo-bronchial tree

• Round, oval or triangular soft tissue densities

• Often found in clusters

Q1: What is the size range for normal lymph nodes?

Answer

Q1: What is the size range for normal lymph nodes?

Normal nodes size range up to 1 cm for mediastinal and 1.5 cm for hilar nodes

Normal lymph node : 1 cm in short axis

• 12 mm for subcarinal node

• 10 mm for right paratracheal node

• 8 mm for others

Q2: Are you aware of the nomenclature for lymph node stations

Answer

Q2: Are you aware of the nomenclature for lymph node stations

Q3: What are the CT descriptive stages of interpretation for lymph nodes?

Answer

Q3: What are the CT descriptive stages of interpretation for lymph nodes?

Stages

• Normal

• Enlarged

• Coalescence

• Diffuse spread

Q4: What are the unique advantages of CT in evaluation of lymph nodes?

Answer

Q4: What are the unique advantages of CT in evaluation of lymph nodes?

• Precise localization

• Ability to evaluate secondary consequences

• Ability to evaluate density with  IV contrast :  (Low density  necrotic, calcified, Vascular)

CT can pick up unsuspected adenopathy from plain radiographs

• Effacement of posterior wall of RUL, intermediate bronchus

• Obliteration of the azygo-esophageal recess or the left retro bronchial stripe

• Posterior hilar adenopathy does not distort the lateral margin of hilum

Q5: What are the radiological characteristics of  lymph nodes that are useful in differential diagnosis?

Answer

Q5: What are the radiological characteristics of  lymph nodes that are useful in differential diagnosis?

• Calcification

• Low central density

• Cavitation    (Tuberculosis)

• Vascular lymph nodes

Q6: List diferential diagnosis of calcified lymph nodes.  (I am not asking for Solitary pulmonary nodule.)

Answer

Q6: List diferential diagnosis of calcified lymph nodes.  (I am not asking for Solitary pulmonary nodule.)

• Tb (homogenous)

• Histoplasmosi

• Silicosis (Egg shell)

• Sarcoidosis

• Hodgkin's following RT

Q7: What is the differential for Egg shell calcification of  nodes

Answer

Q7: What is the differential for Egg shell calcification of  nodes

• Silicosis

• Coal-worker pneumoconiosis

• Sarcoidosis

• Post irradiation Hodgkin's disease

• Histoplasmosis

• Blastomycosis

• Scleroderma

• Amyloid

Q8: List differential diagnosis for low density necrotic nodes (with or without enhancing rim)

Answer

Q8: List differential diagnosis for low density necrotic nodes (with or without enhancing rim)

• Tb

• Fungal

• Cancer

• Seminoma

• Lymphoma

Q9: What is the differential for low central density nodes

Answer

Q9: What is the differential for low central density nodes

• Tuberculosis (particularly in AIDS population)

• Testicular carcinoma

Q10: What is your  differential diagnosis for vascular lymph nodes?

Answer

Q10: What is your  differential diagnosis for vascular lymph nodes?

• Metastases 

  • Renal

  • Papillary thyroid carcinoma

  • Carcinoid 

  • Small cell cancer Lung

• Castleman's disease

• Angio-immunoblastic lymphadenopathy

   

Q11: What is the classical radiological presentation of lymphadenopathy in Sarcoidosis?

Answer

Q11: What is the classical radiological presentation of lymphadenopathy in Sarcoidosis?

Bilateral hilar adenopathy with right paratracheal or AP wndow nodes.

Q12: What is your consideration for paracardiac adenopathy?

Answer

Q12: What is your consideration for paracardiac adenopathy?

Malignancy.

Q13: What are the radiological characteristics of  Hilar Masses/Nodes

Answer

Q13: What are the radiological characteristics of  Hilar Masses/Nodes

• Generalized hilar enlargement

• Focal hilar enlargement

• Compression

• Displacement

• Infiltration of bronchial tree. Abrupt changes in the overall caliber of bronchial tree may indicate diffuse circumferential submucosal tumor infiltration

• Nodularity in contour of hilum is suggestive of adenopathy

Q14: How is CT  evaluation of  lymph nodes useful in lung cancer?

Answer

Q14: How is CT  evaluation of  lymph nodes useful in lung cancer?

• Node location determine procedure (Transcarinal needle aspiration vs Mediastinotomy)

• Node morphology (intranodal vs extranodal) helps in prognosis

• Evaluate for secondary effects (SVC syndrome)

Lymphoma is primary neoplasm of the lympho-reticular system

Q15: How do you classify Lymphoma?

Answer

Q15: How do you classify Lymphoma?

• Hodgkin's Lymphoma
• Non-Hodgkin's lymphoma

Q16: What is the incidence of Mediastinal involvement in Lymphoma?

Answer

Q16: What is the incidence of Mediastinal involvement in Lymphoma?

• Hodgkin's more common in mediastinum
• 50-80 % of HD present with mediastinal adenopathy
• Less than 20% of NHL present with mediastinal adenopathy

Lymphomatous nodes is not distinctive and can range from well-defined nodes to diffuse extensive involvement

Hilar adenopathy in the absence of mediastinal adenopathy is unusual

Q17: What are the characteristics of mediastinal lymph node involvement in HD and NH Lymphoma?

Answer

Q17: What are the characteristics of mediastinal lymph node involvement in HD and NH Lymphoma?

• Anterior mediastinal, Para-tracheal and hilar nodes is 3-4 times more common in HD than with NHL
• Para-cardiac and posterior mediastinal nodes is almost exclusively seen in NHL
• Internal mammary node is 10 times more common in HD than in NHL

Q18: What is the mode of spread in HD and NH Lymphoma?

Answer

Q18: What is the mode of spread in HD and NH Lymphoma?

• HRD is unifocal and spreads by contiguity to involve adjacent lymph node groups
  • Skipped areas are unlikely
• IN NHL the disease can be generalized  And non-contiguous spread is common.

Q19: What is the role of CT in evaluating residual mass in Lymphoma?

Answer

Q19: What is the role of CT in evaluating residual mass in Lymphoma?

• CT has a major role for monitoring size of nodes during therapy
• In some cases residual masses consist of fibrotic residual tissue "sterilized" lymphoma
• Sterilized mass cannot be distinguished from mass containing residual lymphoma

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