Pulmonary Nodular Amyloidosis Mimicking Metastatic Lung Lesion in a Patient with Colon Cancer

Amyloidosis is defined as abnormal aggregation of amyloid proteins. Amyloidosis can be localised or systemic affecting the lung, heart, spleen, liver and kidneys. The most common form of pulmonary amyloidosis is the nodular type. The disease is idiopathic and linked to many systemic diseases. The clinical manifestations and prognosis of respiratory tract amyloidosis depends on its etiology and anatomical location.

Radiologically, the nodular pulmonary amyloidosis may appear as single or multiple nodules in any lobe, and, therefore, may mimic as primary pulmonary or metastatic neoplasms. Here, we report a case of 70-year female who was diagnosed with colon cancer, which was treated by surgery. During metastatic follow-up, her CT chest showed right lung nodule highly suspicious for metastatic lesion from the colon.

Thoracoscopic wedge resection of the lung nodule done after micro-coil localisation technique under CT guidance. The histopathology report showed pulmonary nodular amyloidosis. This case indicates that histological examination is necessary to differentiate a benign pulmonary nodule from a metastatic lung nodule, especially in a patient with underlying malignancy.