Pulmonary Nodules and the Halo Sign: Can We Think of Just One Diagnosis?

Abstract

The halo sign in computed tomography (CT) scan of the chest consists of ground-glass opacity around pulmonary lesions. It has been linked to a wide variety of pathological processes #1.CASE PRESENTATION: Male, 66 years old, admitted for hyperglycemia; he had no respiratory symptoms. At physical examination he presented with jaundice, choluria and acholia. The laparoscopic pancreatic biopsy confirmed the presence of pancreatic cancer. Chest-abdomen-pelvis CT scan were performed for staging, and identified numerous bilateral pulmonary nodules, infracentrimetic, with a circular area of ground-glass attenuation (halo sign), being hypothesized invasive pulmonar aspergillosis or metastatic lesions with associated bleeding, the last one being less likely because the primary lesion had hypovascular behavior. He was subsequently submitted to bronchofibroscopy, whose cytology of the bronchoalveolar lavage was negative for neoplastic cells, identifying the existence of fungal hyphae; the mycological examination was negative. The galactomannan survey was also negative. He repeated bronchofibroscopy in an attempt to identify the fungus, however, the result was also negative. It was decided to perform a transthoracic lung biopsy, which confirmed the presence of metastases. The patient died a few weeks later, due to systemic progression of the neoplasm. DISCUSSION:The halo sign was initially believed to be a specific sign of invasive pulmonary aspergillosis, but it has already been associated with multiple other pathologies, such as, inflammation, infection or cancer #2. CONCLUSIONS:In this case, it is highlighted the difficulty in establishing a definitive diagnosis and the importance of placing multiple hypotheses of diagnosis in the presence of some characteristic radiological signs, such as the halo sign, very suggestive of invasive pulmonary fungal infections in immunocompromised patients, but not specific.