Nodules included in this category are those with margins that are indistinct or poorly defined (tree-in-bud sign).

In radiology, the tree-in-bud sign is a finding on a CT scan that indicates some degree of airway obstruction.

The tree-in-bud sign may appear on the chest CTs of some patients affected by tuberculosis, but it is not specific to tuberculosis.

The tree-in-bud sign is a nonspecific imaging finding that implies impaction within bronchioles, the smallest airway passages in the lung.

Radiographic imaging of the chest often shows hyperinflation, increased vascular markings, tree-in-bud sign, and the appearance of a "not quite normal chest radiograph".

Cavitation or consolidation of the apexes of the upper lobes of the lung or the tree-in-bud sign may be visible on an affected patient's chest X-ray.