Approach to a solid solitary pulmonary nodule in two different settings-"Common is common, rare is rare"

Abstract

A new solid solitary pulmonary nodule (SPN) is a common feature in the daily practice of physicians, pulmonologists and thoracic surgeons. The etiology and consequently the diagnostic approach is very different in various parts of the world. Identification of malignant nodules is the universal goal to proceed to a potential curable therapy. In countries with a low incidence of inflammatory disease and a high incidence of lung cancer the diagnostic work up includes a positron emission tomography (PET) scan or PET-computer tomography (CT) as a main pillar. In countries with a high incidence of inflammatory and infectious disease and a low incidence in lung cancer this diagnostic work up needs to be adapted. In these settings a PET scan has a limited role and tissue diagnosis, whether with a trans-thoracic, trans-bronchial biopsy or a video-assisted wedge resection is the most targeted approach to determine or exclude malignancy. The evaluation of a solid SPN in the two different situations is outlined in our algorithm. Recommendations stress the value of clinical judgement in different settings, determination of probabilities of malignancy, cost-effective use of diagnostic tools and evaluation of various management alternatives according to the risk profile and the patients preferences.

Keywords: Solitary pulmonary nodule (SPN); algorithm; diagnostic work up; inflammatory lung disease; lung neoplasms.

Figure 1

CT of a solid SPN, which was followed up closely and has slightly grown in size (from 1.1 to 1.4 cm) in a 65-year-old heavy smoker from China. With spiculae present, no calcifications and 66 Hounsfield Units it was most likely malignant (high risk category with a calculated probability of 88.1%): VATS wedge, frozen section (Adenocarcinoma), VATS lobectomy with lymph node dissection. Final histology: pT1bN0M0, Stage I NSCLC.

Figure 2

CT of new solid SPN in the right lower lobe, size 1 cm, smooth appearance, no spiculae, HU 26, detected on routine CXR in a 50-year-old from Europe, non-smoker, NIDDM, most likely benign with a calculated probability for malignancy of 2.4%. Control CT in three months.

Figure 3

Algorithm solid single pulmonary nodule (SPN), adapted from Patel et al. (5). *, Pre test probability. i.e., Swensen et al. Factors to determine the probability of malignancy: age, smoking history, previous malignancy >5 y ago, presence of spiculation, upper lobe location. **, Fleischner Society Guidelines (Table 3); ***, ACCP Guidelines 2007: serial CT scan at 3, 6, 12, and 24 months.

Figure 4

PET positive solid SPN left lower lobe: on the left is a maximum intensity projection (MIP) of the total body F18-FDG PET investigation. On the right there are three transverse slices of the hybrid F18-FDG PET/CT investigation. The single pulmonary nodule (SPN) dorso-caudal of the left hilum shows a maximum standardized uptake value (SUV_max) of 12. The corresponding CT slice reveals a hyperdense lesion with a diameter of 2.1 cm, HU 60 and a calculated probability for malignancy of 88.5%. Final histology after resection: pT1bN0M0, Stage 1 NSCLC.

Figure 5

PET scan of a solid SPN in the right lower lobe. On the left: maximal intensity projection (MIP) of the total body F18-FDG PET investigation: no lesion visible. On the right: (above) transverse slice CT in lung settings shows a 2 cm lobulated lesion with ill defined edges and varying densities, HU –55 to +75; (below) two transverse slices of the hybrid F18-FDG PET/CT investigation showing activity not significantly above the background activity [standardized uptake value (SUV) <1.5]. Calculated probability for malignancy: 8.4%.

Figure 6

CXR posterior-anterior (PA) on the left: a new SPN in the left upper lobe, size ~2 cm, smooth, vague borders, no calcifications, TTNB positive for AFB’s. On the right: after three months of standard anti-TB treatment, the lesion is less dense and decreased in size (1.2 cm).

Figure 7

CT scan of a new solid SPN in a 62-year-old smoker with COPD and a pacemaker, calculated probability for malignancy: 55.2%. (A) smooth, homogenous opacity in the right middle lobe, no calcifications, proven to be a caseating granuloma on TTNB; (B) CT scan of the same patient six months after anti-TB treatment. Only a small holter is left in the antero-medial aspect of the right middle lobe.

Figure 8

High resolution CT scan of a 60-year-old female, heavy smoker. A solid SPN in the right upper lobe was seen on CXR. CT scan shows a spiculated, ~2 cm lesion without calcifications, calculated probability for lung cancer: 66.4% in the absence of a PET, bronchoscopy and lavage did not reveal a diagnosis. A TTNB only showed necrosis, a wedge excision was performed and frozen section revealed a caseating granuloma compatible with TB.