SPN Ii is defined as a focal opacity ,visible on chest radiograph or CT ,with the following criteria :1.Relatively well defined .2.Surrounded-at least partially - by lung .3.Roughly spherical in shape.4.3 cm or less in diameter (more than 3 cm is termed mass )
Clinical evaluation Hx of smoking. Age over 40. Occupational exposure. Lung fibrosis. COPD. Family Hx of Lung cancer. Travel History TB skin test. Other diseases (Rheumatoid arthritis ) Malignancy .(solitary metastasis or increased likelihood of 1ry bronchogenic Ca for H & N breast ,bile ducts ,oes. ,cervix ,bladder ,prostate ,etc up to 3 folds )
I-Morphological Characteristics Size : Diameter Malignancy The likelihood of rate malignancy is directly 1cm> 35% related to size reaching more than 85 % for SPN more than 2 cm . cm 1-2 50% cm 2-3 80%
Location : 2/3 of lung cancers occur in upper lobes. 60% seen in lung periphery . Only 10 % seen in medial third . Mets tend to be subpleural or outer 1/3 of lung. 2/3 of mets are in lower lobes.
Edge Appearance :90% of lesions with irregular or spiculated edges are malignant.20% only of well defined lesions are malignant (e.g.: Mets or carcinoid tumor )Corona Maligna or radiata represent either desmoplastic reaction around the tumor or actual invasion of surrounding lung …common with BAC and adenocarcinoma
Halo sign Halo of ground glass opacity surrounding a nodule .Commonly present in Leukemic patient with invasive aspergillosis (represent hemorrhagic infarction )Can occur with any other infections .Can be seen with BAC and adenocarcinoma (representing lepidic growth )
Causes of Halo signInvasive aspegillosis.Wegener Granulomatosis.BAC.Kaposi sarcoma.Mets.TB, nocardiosis.CMV infectionPCPBOOP
Shape :Lung Ca tends to be irregular , lobulated or notched.Granuloma are rounded.Hamartoma and metastasis are round ,oval or lobulated.Scars , atelectasis may appear linear .AVM and mucous plugs are particular in shape
III-Growth Doubling time is the time required for a lesion to double its volume . 26% increase in nodule diameter is one doubling Doubling of diameter is 3 volume doublings. Range of doubling time of carcinomas is 1 week to 16 months. Doubling time <1 month or >200 days is likely to be benign . No growth over 2 years most likely benign.
?How to evaluate.See prior examinationsIf not availableSmall lesions follow up is at 3,6 months ,1 and 2.yearVery small lesions (3mm)..yearly follow up
SPECT & PET Scan additions Using FDG high activity in PET is associated with malignancy