Survival Guide to Findings in the Lower Chest

CHAPTER 25 Survival Guide to Findings in the Lower Chest

Neal C. Dalrymple, Monica Dalrymple, Constanza J. Gutierrez

As it turns out, the curved configuration of the diaphragm is rather inconvenient to the way radiologists partition training and reference material. Computed tomographic (CT) and magnetic resonance imaging (MRI) examinations necessarily include portions of the inferior thorax to include all of the abdominal contents. Although an exhaustive number of texts address the abnormalities encountered in the chest, some of the chest findings most commonly encountered when interpreting CT scans of the abdomen are summarized in the following table.

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Tags: Problem Solving in Abdominal Imaging

Mar 6, 2016 | Posted by admin in GENERAL RADIOLOGY | Comments Off

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Finding	Differential Diagnosis and Comments
Lung Nodules
*Small Incidental Nodule*
	Differential considerations include: granuloma, metastasis, early lung cancer. • Small nodules are usually remnants from prior infection or inflammation, although spiculation or history of malignancy makes any nodule more suspicious. • Calcification usually indicates benignity (granuloma or hamartoma) although some metastases calcify including osteosarcoma and thyroid cancer (calcified miliary nodules) or less commonly in chondrosarcoma and colon and breast cancer. General Guidelines: • If not already included, consider obtaining CT scan of entire chest to confirm this is the only nodule. • According to the recommendations put forth by the Fleischner Society, if it is the only nodule and the patient has no history of malignancy or significant smoking history: • ≤4 mm: no action necessary • >4-6 mm: surveillance CT in 12 months; if no change, then no further imaging • >6-8 mm: surveillance CT in 6-12 months; if unchanged, follow up again in 18-24 months • >8 mm: surveillance CT at 3, 9, and 24 months (if remains unchanged); consider PET or biopsy • More aggressive follow-up and progression to PET and/or biopsy for patients at greater risk for malignancy (see Suggested Readings for more information.)
*Multiple Small Nodules*
	Differential diagnosis includes metastases, active atypical infection, sequelae of prior infection, hypersensitivity pneumonitis. • Metastases: Pulmonary metastases may be associated with lymphadenopathy, pleural effusion, other metastases (liver, adrenal gland), and may be cavitary. • Active atypical infection: Infectious nodules often have indistinct margins, lymphadenopathy, halo sign (zone of ground glass opacity around nodule). • If nodules are calcified, consider prior histoplasmosis or varicella infection vs. metastatic thyroid cancer. • Acute hypersensitivity pneumonitis can cause indistinct centrilobular nodules.
*Multiple Large Nodules*
	Differential diagnosis includes metastases, Wegener’s granulomatosis, Rheumatoid nodules. • “Cannonball” metastases most often occur with colon cancer, germ cell tumors, sarcoma, renal cell carcinoma • Wegener’s granulomatosis: nodules often cavitate, airspace disease and large airway stenosis (usually subglottic) may be present • Rheumatoid nodules: rare manifestation of rheumatoid lung disease, usually associated with more common manifestations including interstitial fibrosis and bronchiectasis
*Ground Glass Nodule*
	Differential diagnosis includes lung cancer, inflammatory and infectious disease, vasculitis, eosinophilic pneumonia. • Lung cancer: bronchoalveolar cell carcinoma, adenocarcinoma and atypical adenomatous hyperplasia (a precursor to adenocarcinoma) can present as ground-glass nodules. PET is usually negative in cases of bronchoalveolar cell carcinoma. • Cryptogenic organizing pneumonia: usually bilateral, patchy distribution and ground-glass opacity is often mixed with more confluent consolidation. Regions of opacity can be migratory. • Vasculitis: ground-glass nodules can occur with smalland medium-vessel vasculitis, often associated with hemoptysis. • Eosinophilic pneumonia: peripheral ground-glass opacities, sometimes nodular. Many etiologies, including drug reaction, parasitic infection, collagen vascular disease. • Consider short-term imaging follow-up for those too small to biopsy.
*Mixed Ground Glass/Solid Nodule*
	Differential diagnosis includes lung cancer, hemorrhagic metastases, aspergillosis, cryptogenic organizing pneumonia, vasculitis, eosinophilic pneumonia. • Lung cancer: These lesions have a higher likelihood of malignancy than uniformly solid solitary pulmonary nodule (adenocarcinoma shown in Fig. A). Biopsy if possible, otherwise close imaging surveillance. • Hemorrhagic metastases: Most common with choriocarcinoma and renal cell carcinoma. • Aspergillosis: Pulmonary hemorrhage related to angioinvasive aspergillosis results in halo sign (shown in Fig. B). • Cryptogenic organizing pneumonia (COP): Ground-glass opacity nodule with surrounding ring of higher attenuation (reverse halo sign) thought to be specific for COP.
*Cavitating Nodule(s)*
	Differential diagnosis includes metastases, septic emboli, atypical pulmonary infections, Wegener’s granulomatosis, rheumatoid nodules. • Metastases: Cavitation common with squamous cell carcinoma primary tumor (cervical cancer metastasis shown), rarely with adenocarcinoma. • Septic emboli. • Atypical pulmonary infections: Cavitation associated with pulmonary tuberculosis and invasive aspergillosis (air crescent sign). • Wegener’s granulomatosis: Cavitating nodules are a common feature. Can be associated with subglottic stenosis. • Wall morphology can be useful in narrowing differential diagnosis: • Thin wall: consider superinfection of preexisting cyst or bulla. • Thick wall: consider malignancy, tuberculosis, aspergillosis.
Abnormalities of Enhancement