Diagnosis: Primary lung cancer (adenocarcinoma) in RLL
with miliary metastasis and pericardial seeding

Radiologic Findings

Chest PA shows innumerable multiple tiny nodules uniformly distributed throughout both lungs.
Chest lateral shows suspicious ovoid opacity in lower lung zone.
HRCT shows numerous miliary nodules in diffuse and random distribution in both lungs.
Some linear densities are noted in peripheral portion suggesting interlobular and intralobular septal thickening.
Irregular spiculated ovoid mass is noted in RLL.
Moderate amount of pericardial effusion is noted.

Brief Review

DMLD (diffuse micronodular lung disease), each nodule being < 3mm in diameter and occupying more than two-thirds of lung volume on chest radiograph, can be differentiated by its distribution.

Centrilobular distribution is seen in DPB (diffuse panbronchiolitis), infectious bronchiolitis, H. influenza, bronchogenic disseminated tuberculosis, pneumoconiosis, primary lymphoma, and foreign body-induced necrotizing vasculitis.

Perilymphatic distribution is noted in pneumoconiosis, sarcoidosis, amyloidosis.

Random distribution is found in miliary tuberculosis and pulmonary metastasis.

The nodules in pulmonary metastatic disease appeared to be slightly larger and are more variable in size than those in miliary tuberculosis. They show relatively well defined margins.
Miliary metastases are most likely to be due to thyroid, renal carcinoma, bone sarcoma, trophoblastic disease, or melanoma.

References

1. Lee KS, Kim TS, Han J, et al. Diffuse Micronodular Lung Disease: HRCT and Pathologic Findings. JCAT1999;23(1):99-106.
2. Hong SH, Im JG, Lee JS, et al. High-resolution CT findings of miliary tuberculosis. JCAT 1998;22(2):220-224.
3. P. Amstrong, A. G. Wilson, P. Dee et al. Imaging of Diseases of the Chest. 2nd ed. St. Louis, Mosby-Year Book, 1995; 344-350.