1. Evaluation of Solitary Lung Mass
Vishal Sagar, M.D.
Chicago Medical School
Chicago, Illinois

2. Pulmonary Mass vs Pulmonary Nodule
Most authorities consider a size of 3-4 cms as the cut off limit for differentiation between pulmonary mass and pulmonary nodule
Reason for differentiation- different etiologic factors need to be considered if the size is greater than 3-4 cms

3. Classification of Etiologic factors in a Solitary Pulmonary Mass
Developmental
Infectious
Neoplastic
Inhalational
Traumatic
Immunologic

4. Developmental Intralobar sequestration
Almost invariably contiguous to the diaphragm in the posterior bronchopulmonary segment
Typically well defined margin
Cyst formation relatively common
Although cystic in nature, mass remains homogeneous until communication is established with contiguous lung as a result of infection

5. Infectious Granulomas
Histoplasmosis
Coccidiodomycosis
Tuberculosis
Atypical Mycobacteria
Cryptococcosis
Blastomycosis

6. Lung Abscess
Predilection for posterior portions of upper or lower lobes
Tends to be round
Ill defined margins when acute but well defined when chronic
No calcification
Cavitation is common
Etiology- usually Staph or anaeobes
Mass may remain unchanged for many weeks

7. Other Infections Ascariasis Pneumocystis Carinii Aspergilloma
Paragonimus Westermani
Hydatid Cyst

8. Hydatid Cyst Causative organism- Echinococcus Granulosus
Predilection for lower lobes
Tends to have bizarre, irregular shape
Calcification may be seen - though extremely rare

9. Neoplastic
Benign
Malignant
Primary Lung Ca
Metastatic

10. Benign Tumors
Hamartoma
Lipoma
Fibroma

11. Characteristics that help determine benign nature of the pulmonary mass
Age less than 35
Absence of risk factors like smoking or exposure to occupational carcinogens
Small size of the mass ( Size of > 3 cms is associated with an 80% chance of malignancy)
Doubling time < 20 Days or > 400 Days
Certain patterns of calcification
Diffuse
Central
Laminated
Pop corn

12. Primary Pulmonary Carcinoma
Even though all cell types of lung cancer can present as a solitary peripheral lung mass- it is most commonly seen in adenocarcinoma
Margins tend to be ill defined
Foci of calcification seen on CT in about 5% to 10% of large tumors
Cavitation relatively common

13. Metastasis
Uncommon for pulmonary metastasis to present as a solitary mass
Tends to be sharply defined and lobulated
Calcification is rare- almost exclusively restricted to metastatic osteogenic sarcoma or choondrosarcoma

14. Inhalational Foreign Body Inhalation Lipid Pneumonia Silicosis
Coal Workers Pneumoconiosis
Round Atelectasis

15. Foreign Body Inhalation
Broken fragments of teeth
Food particles
Flowering heads of various grasses
Oral medications
Patients might give a history of recent dental work, general anesthesia or there might be a history of altered consciousness predisposing them to foreign body inhalation/aspiration

16. Lipid Pneumonia
Inflammatory reaction associated with oil or fat in the alveoli
Usually aspiration of mineral oil used as laxative
Dependent portions of upper and lower lobes
Well defined shape but often has a shaggy outer margin
No calcification seen
CT scan often allows specific diagnosis by demonstrating foci of fat attenuation

17. Silicosis
Initially involves the periphery of the mid and upper lung zones
Margins may be irregular and somewhat ill defined, simulating pulmonary carcinoma
A background pattern of diffuse silicosis may be apparent
Hilar lymph node enlargement is common and may be associated with “eggshell calcification”

18. Coal Workers Pneumoconiosis
Marked predilection for upper lobes
Shape- similar to large opacities of silicosis
Calcification generally not seen
May Cavitate
A background of diffuse nodular or reticulonodular shadows is usually evident

19. Round Atelectasis Most commonly associated with asbestos exposure
Lower zonal predominance, abuts localized area of pleural thickening
Shape is generally round or oval
No calcification
CT shows the mass abutting a thickened pleura; vessels and bronchi curve toward the periphery of the mass

20. Traumatic Pulmonary Hematoma
Usually deep to the point of maximal trauma
It is generally sharply defined, round or oval-
No calcification
No cavitation
Resolution may take several months

21. Immunologic Wegners Granulomatosis Sarcoidosis
Extremely Rare for these to present as solitary lung mass

22. References Focal and Multifocal Lung Disease,
ScientificAmerican Medicine, IV, 1-19
Textbook of Respiratory Medicine, 3rd
Edition,Murray, Nadel, Mason, Boushey.
Fraser and Pare's Diagnosis of Diseases of the
Chest, 4th edition- Fraser, Muller, Colman, Pare.
Textbook of Pulmonary Diseases, Fifth edition-
G.L.Baum, Emanuel Wolinsky.