Small Nodules with Random (Miliary) Distribution

CT Findings

Common TSCT findings of alveoloseptal amyloidosis include reticular opacity, interlobular septal thickening, and small nodules. Small nodules (2–4 mm diameter) are usually multiple and subpleural (Fig. 18.11). Less common findings are ground-glass opacity, traction bronchiectasis, and honeycombing [49, 50].

CT–Pathology Comparisons

TSCT findings of alveoloseptal amyloidosis are caused by the deposition of amyloid in the parenchymal interstitium and in the media of small blood vessels.

Patient Prognosis

Pulmonary involvement is not a major contributor to death in systemic amyloidosis, and the median survival of patients with clinically overt lung deposition is about 16 months [51].

relationship to any anatomic structures [1]. In random distribution, the small nodules are diffusely seen in all lobes of both lungs and affect the lungs either equally or symmetrically. There is no thickening in the interstitium, both axially (peribronchovascular) and peripherally (interlobular septa) [2] (Fig. 18.13).

Diseases Causing the Pattern

Miliary tuberculosis (TB) (Fig. 18.14) and miliary metastases (Fig. 18.15) are the two most common conditions that manifest random nodules in both lungs [1]. Small nodules of random distribution can also be observed in disseminated fungal (e.g., Candida albicans and cryptococcosis) and viral pneumonias and in sarcoidosis [52, 53].

Distribution

In most diseases, lung abnormalities show random and diffuse in distribution. In sarcoidosis, the miliary nodules may show peripheral (subpleural) distribution [53].

Small Nodules with Random (Miliary) Distribution

Definition

Small nodular lesions considered random in distribution when the nodules did not show either a centrilobular or a perilymphatic distribution. In other words, they are uniform and even in distribution without a consistent or predominant

Clinical Considerations

The small miliary lung nodules in miliary TB may be associated with diffuse ground-glass opacity (GGO) (acute lung injury) [54] or cystic lung lesions [53, 55]. Lung adenocarcinoma is one of primary cancers that are associated with miliary pulmonary dissemination of the cancer. Therefore, the primary lung adenocarcinoma per se is seen through miliary metastatic lung nodules [56].