The angiogram sign in lung consolidation: what is its diagnostic value? l segno dell'angiogramma nelle consolidazioni polmonari: quale valore diagnostico?

The angiogram sign in chest CT is the demonstration of normally enhanced pulmonary branches within hypoattenuating lung parenchyma consolidation. In a retrospective review of the chest CT exams performed in a 2-year period, we identified the angiogram sign in 10 patients with lung consolidation; the diagnosis was central lung tumor with obstructive pneumonia in 4 patients, bronchioloalveolar carcinoma in 2 patients, postirradiation fibrosis in 1 patient, tuberculous pneumonia in 1 patient, lung lymphoma in 1 patient and metastasis from pancreatic tumor in 1 patient. The diagnosis was made with cytology and/or surgical specimen in 9 patients and with clinical-radiologic follow-up in 1 patient. The density, air and mucous bronchogram and the volume loss in the consolidated lung were also considered. The consolidated lung density was < 30 HU in 5 patients -one bronchioloalveolar carcinoma, one metastasis from pancreatic carcinoma and 3 obstructive pneumonia cases -, while it was > 30 HU in the extant 5 patients. The air bronchogram sign was observed in 4 cases - one bronchioloalveolar carcinoma, one metastasis, one postirradiation fibrosis and one lung lymphoma -, while a mucous bronchogram was observed in 3 patients with obstructive pneumonia. Lung volume was reduced only in 2 patients - one obstructive pneumonia and one postirradiation fibrosis. In our opinion, the CT angiogram sign must be considered a poorly specific sign, because it can be found in many pathologic processes, both benign and malignant. If associated with the other features of lung consolidation, the CT angiogram sign can help diagnose, together with clinical findings and the patient's history, the pathologic condition. Particularly, the angiogram sign within a hypoattenuatcd lung consolidation area can be found in obstructive pneumonia, while the angiogram sign within a hypoattenualed consolidation with an air bronchogram probably indicates a mucinous carcinoma with lepidic growth.