Evaluation of Solitary Lung Mass

1
Evaluation of Solitary Lung Mass

• Vishal Sagar, M.D.
• Chicago Medical School
• Chicago, Illinois

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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

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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

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Infectious Granulomas

• Histoplasmosis
• Coccidiodomycosis
• Tuberculosis
• Atypical Mycobacteria
• Cryptococcosis
• Blastomycosis

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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

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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

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Benign Tumors

• Hamartoma
• Lipoma
• Fibroma

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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 gt 3 cms is
  associated with an 80 chance of malignancy)
• Doubling time lt 20 Days or gt 400 Days
• Certain patterns of calcification
• Diffuse
• Central
• Laminated
• Pop corn

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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

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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

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Inhalational

• Foreign Body Inhalation
• Lipid Pneumonia
• Silicosis
• Coal Workers Pneumoconiosis
• Round Atelectasis

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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

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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

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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

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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

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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

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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

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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.