Clinical History
An asymptomatic 50-year-old woman was found to have an incidental pulmonary abnormality in a preoperative chest X-ray. She underwent surgery in 2007 from a pheochromocytoma and a parotid tumour. She suffered from Sjögren's syndrome and was waiting to be operated for a pancreatic cystic tumour.
Imaging Findings
Chest X-ray revealed the presence of multiple pulmonary nodules, the biggest with 25 mm in diameter in the upper segment of the right lower lobe (RLL) (Fig. 1).
Computed tomography showed multiple pulmonary nodules with a peripheral distribution and well-defined edges. They varied from 5 to 18 mm in diameter, with the largest one located on the apical segment of the RLL (Fig. 2). They were not calcified or cavitated. Neither pathologically-sized lymph nodes nor signs of pleural disease were found.
As oncologists suggested metastasis of previous pheochromocytoma (neuroendocrine malignancy), SPECT was made. However, it demonstrated absence of pulmonary uptake after intravenous administration of Octreotide-In 111 (Fig. 3).
Discussion
In the presence of multiple pulmonary nodules (MPN), we must bear in mind some details regarding the differential diagnoses [1]:
- According to the patient's medical history, the semiology of the described nodules is compatible with metastatic lesions. Also the possibility of a primary pulmonary lesion could not be dismissed, although the X-ray presentation was not the typical one. In view of the pheochromocytoma antecedent, SPECT was made. It was negative, however, it did not discard malignancy (Fig. 3).
- Rheumatoid nodules, nodular sarcoidosis or other inflammatory diseases may cause MPN. Other less frequent entities include vasculitis, pneumoconiosis and amyloidosis. However, laboratory and clinical parameters were not suggestive of such entities.
- Granulomatous diseases (e.g. tuberculosis), septic embolism, lung abscess, fungal or viral infections and other parasites may cause MPN. However, radiological signs are not typical of any of them and the clinical and laboratory data were not suggestive of such possibilities.
- Vascular malformations should have been observed in previous studies. Pulmonary infarction may cause MPN but the patient did not show pulmonary embolisms.
Due to lack of specificity of the findings, the multidisciplinary committee agreed to perform a CT-guided pulmonary biopsy of the largest lesion (Fig. 2c).
The first biopsy cylinder was successfully obtained. However, immediately the patient developed an intense cough associated with haemoptysis that required postural measures, oxygen therapy and aspiration of material accumulated in the bronchial tree. Procedure was then stopped.
Tissue obtained by fine needle aspiration biopsy shows typical findings in pulmonary amyloidosis (Fig. 4): the normal lung is replaced by a mass of amorphous, eosinophilic, extracellular Congo red-positive material.
First control of pulmonary nodules 5 months after detection has shown no changes.
The most frequent form of pulmonary amyloidosis is nodular amyloidosis [2, 3] and it is usually a local process. Its X-ray appearance may be indistinguishable from neoplastic lesions. It may appear as solitary or multiple pulmonary nodules, which are rounded and well-defined. Cases of irregular edges are usually due to vascular involvement or to involvement of adjacent septa. Lesions generally grow slowly and have therefore a good prognosis.
Diffuse septal involvement (amyloid deposits in alveolar septa) is less frequent, although it is associated with higher clinical involvement due to a higher risk of pulmonary hypertension and respiratory insufficiency [4]. In such cases, a much more varied semiology may be found: micronodules (2-4 mm), septal thickening, reticular opacity, basal peripheral consolidations that tend to converge, pleural effusion, pleural thickening, etc.
Differential Diagnosis List
Nodular amyloidosis
Metastasic or primary malignant nodules
Nodular sarcoidosis
Pneumoconiosis (e.g. silicosis)
Granulomatorus diseases (e.g. tuberculosis)
Reumathoid nodules
Fungal or viral infections
Vascular malformations
Pulmonary infarctions
